Theor Appl Genet (1995) 90:1158-1163
9 Springer-Verlag 1995
C. R. Riede 9N. D. Williams - J. D. Miller. L. R. Joppa
Chromosomal location of genes for stem rust resistance derived from 'Waldron' wheat
Received: 9 June 1994 / Accepted: 18 June 1994
A b s t r a c t The chromosomal locations of genes for resistance to stem rust (Puccinia graminis Pers.: Pets. f. sp. tritici Eriks. & E. Henn.) in the wheat (Triticum aestivum L.) cultivar 'Waldron' (WDR) were determined by monosomic analyses. Wheat lines WDR-B 1, -C2, -E4, a n d - F l , w h i c h have single genes for resistance to stem rust derived previously from WDR sel. 'Little Club', were crossed onto a complete set of 21 'Chinese Spring' monosomics. The F 2 and backcross-F 1 (BC1F 1) seedlings from each of the 84 crosses were tested for reaction to culture 111-SS2 (CRLLCBB) of stem rust, and a few selected segregants were analyzed cytologically for chromosome number. The F 2 from 2 crosses of WDR-C2, -E4 and -F1 and the BC1F 1 from 2 crosses of WDR-F1 were tested also with culture Or 1 lc (CRL-QBCN). Significant deviations from disomic ratios towards monosomic ratios in the F 2 and BC1F 1 were used to determine which chromosomes carried the genes for resistance. Cytological analyses of certain BCIF 1 and susceptible F 2 plants were used to help identify the location of the genes for rust resistance. WDR-B 1 has a gene, herein designated Sr41, for resistance on chromosome 4D. WDR-C2 has a gene on chromosome 7A that may be the same as one previously designated SrWld2. WDR-E4 has a gene on chromosome 2A, possibly SrWldl, which is effective against most or all North American stem rust cultures. WDR-F1 has a gene on chromosome 6B that is the same as or similar to S r l l .
Communicated by G. E. Hart C. R. Riede ([]) Instituto Agron6mico do Paranfi-IAPAR/CNPq,Cx. Postal 1331, 86001-Londrina-PR, Brazil N. D. Williams 9J. D. Miller. L. R. Joppa Agricultural Research Service, USDA, RO. Box 5677, SU Stn., Fargo, ND 58105, USA This paper is a contribution of the North Dakota Agricultural Experiment Station, Agricultural Research Service, U.S. Department of Agriculture, Journal series No. 2165
Key words Triticum aestivum 9Puccinia graminis 9 Aneuploid 9 Cytogenetics 9Monosomics
Introduction Stem rust of wheat (Triticum aestivum L.) caused by Puccinia graminis Pers.: Pets. f. sp. tritici Eriks. and E. Henn is a serious disease that can severely reduce the yield and quality of a wheat crop. The epidemics caused by race 56 in 1935 and race 15B from 1950 to 1954 resulted in severe losses. The major method for control of stem rust has been through the breeding of resistant cultivars using race specific genes for resistance. The hard red spring wheat cultivar 'Waldron' (WDR) was grown extensively in North Dakota for many years (Smith 1978). 'Waldron' has shown a high level of resistance to infections of the stem rust fungus. Resistance is exhibited in both seedling and adult plants and extends to both prevalent and nonprevalent races of the rust population in North America (Williams and Miller 1982). Inheritance studies indicated that WDR possesses one, two, or four effective genes for resistance to stem rust, depending upon the culture of stem rust used (Williams and Miller 1982). Through selection of wheat lines monogenic for resistance from WDR, Riede et al. (1995) showed that WDR has at least six genes for resistance to stem rust. McVey and Roelfs (1978) determined that WDR was heterogeneous for reaction to certain rust cultures. Based on reactions to stem rust cultures, they indicated that about 50% of the WDR plants they tested possessed S r l l , and 20-25% possessed Sr5. Also, they found a dominant gene tentatively designated SrWldl that appeared to give resistance to most or all North American isolates of stem rust. Another gene tentatively designated SrWld2 gave resistance to a limited number of rust isolates. Roelfs et al. (1983) surveyed the occurrence of stem rust in the United States and Mexico in 1981. Their data indicated that there was no virulence in bulked urediospore collections from seedlings with SrWldl.
t159 A n e u p l o i d a n a l y s e s have been a d v o c a t e d b y several authors ( K u s p i r a and U n r a u 1959; L a w and W o r l a n d 1972; M o r r i s and Sears 1967; Sears 1954) and used to locate gene(s) on w h e a t c h r o m o s o m e s by m a n y others ( A n d e r s o n et al. 1971; B e d o et al. 1979; D y c k and K e r b e r 1977; K o s ner and Bartos 1982). The s e g r e g a t i o n ratio for a trait cond i t i o n e d b y a gene on the m o n o s o m e o f a m o n o s o m i c plant d e p e n d s u p o n the t r a n s m i s s i o n rate o f the m o n o s o m e in m a l e and f e m a l e gametes. F o r d o m i n a n t , m o n o g e n i c resistance, only the n u l l i s o m i c p r o g e n y o f a selfed critical m o n o s o m i c plant w o u l d be susceptible, and the p r o p o r t i o n o f s u s c e p t i b l e offspring w o u l d be l o w e r than e x p e c t e d for a d i s o m i c ratio o f non-critical m o n o s o m i c s . Thus, deviating s e g r e g a t i o n ratios can be used to locate genes to specific c h r o m o s o m e s . H o w e v e r , the p r o c e d u r e requires cyt o l o g i c a l e x a m i n a t i o n s to identify the c h r o m o s o m a l constitution of plants, e s p e c i a l l y the p a r e n t a l and F 1 plants. Six w h e a t lines h a v i n g single genes for resistance to stem rust were s e l e c t e d f r o m s e g r e g a t i n g generations f r o m ' W D R ' s e l . / ' L i t t l e C l u b ' (LC) (Riede et al. 1995). The location o f W D R genes for stem rust resistance on specific c h r o m o s o m e s will p r o v i d e v a l u a b l e i n f o r m a t i o n that m a y be u s e d b y geneticists, pathologists, and p l a n t breeders. F o u r o f the six m o n o g e n i c lines were used in crosses to the ' C h i n e s e S p r i n g ' (CS) m o n o s o m i c s . The o b j e c t i v e was to d e t e r m i n e the c h r o m o s o m a l l o c a t i o n s o f genes for resistance to stem rust in the four lines.
Materials and methods Wheat lines having single genes derived from 'WDR' for resistance to cultures of races 111 and 151 of the stem rust fungus (P. graminis f. sp. tritici) were studied by means of aneuploid analysis. The seeds of parental cultivars WDR (C.I. 13958), 'LC' (C.I. 4066), and 'CS' (C.L 6322) were obtained from seedstocks at the North Dakota Agricultural Experiment Station, Fargo, N. D. The monosomic lines of 'CS', developed by E.R. Sears (1954), were obtained from L.R. Joppa, Fargo, N. D. Four monogenic lines designated WDR-B 1, WDR-C2, WDR-E4, and WDR-F 1 that were developed from progenies of WDR sel./'LC' (Riede et al. 1995) were crossed as male parents to 21 lines, each monosomic for a different chromosome of 'CS'. Monosomic (2n = 20" + 1') and disomic (2n = 21") Fls were selfed and backcrossed onto euploid 'CS' (2n = 21"). Two other monogenic lines developed from 'WDR' sel./'LC', WDR-A1 and WDR-D1, will be evaluated later. A root tip squash technique was used for initially determining the number of chromosomes of the female parents and B C 1F1 seedlings. Root tips were treated in a saturated solution of l-bromonaphthalene for 4-5 h, fixed in Farmer's solution overnight, hydrolyzed in 1 M HC1 at 60-70~ for 10 min and stored in 70% ethanol. Chromosome counts were made on root tips stained in leuco-basic-fuchsin and aceto-carmine and squashed between a glass slide and a coverglass. Aceto-carmine smears of pollen mother cells (PMCs) (Belling 1921) were used to verify the chromosome number of the parents before their use in crosses. The F 2 and BCIF 1 seedlings were tested for their reaction to the stem rust fungus (P. graminis f. sp. tritici). The number of seedlings required for an accurate differentiation between a disomic and monosomic ratio was calculated by methods given by Hanson (1959). Approximately 150 F 2 and a minimum of 10 BC 1F1 seedlings from each monosomic F 1 family were tested. The stem rust inoculum was obtained from urediospore cultures of P. graminis f. sp. tritici maintained in liquid nitrogen at the North
Dakota Agricultural Experiment Station, Fargo, N. D. Culture 111SS2 (CRL-LCBB) (Roelfs and McVey 1974) had reddish-brown urediospores and culture Orl lc (CRL-QBCN) had orange urediospores. The methods of inoculation and scoring of the stem rust reaction have been described previously (Riede et al. 1985). Phenotypes were recorded in terms of infection types as described by Stakman et al. (1962). Significant deviations from disomic ratios toward monosomic ratios were used to identify the specific chromosomes that carried the genes for resistance. The exact monosomic ratio depends on the transmission rate of the univalent chromosome and varies with environment and among the 21 different monosomic lines (Khush 1973; Morris and Sears 1967). Chi-squarc tests were used for analyzing data from segregating populations. The chi-square test for heterogeneity was used to determine if the results of non critical crosses could be pooled (Mather 1963). Cytological analysis of PMCs or root tip cells in certain F 2 or backcross-FI plants was used along with reactions to stem rust to help identify the chromosomes bearing the genes for resistance.
Results and discussion The infection types o f the four m o n o g e n i c lines and parental cultivars are p r e s e n t e d on Table 1. The resistant d o n o r cultivar ' W a l d r o n ' had infection type ;, w h e n tested with both cultures 111-SS2 and O r l l c , and the s u s c e p t i b l e controls ' C S ' and ' L C ' had infection t y p e 34. The four lines had distinctly resistant reactions to both cultures, with the e x c e p t i o n o f B a, w h i c h was resistant only to culture 111SS2. The results f r o m m o n o s o m i c a n a l y s e s are p r e s e n t e d as follows:
M o n o s o m i c analysis o f W D R - B 1 Significant deviations f r o m d i s o m i c ratios t o w a r d m o n o s o m i c ratios were o b s e r v e d in the p r o g e n y o f CS m o n o 4 D / W D R - B 1. T h e s e results i n d i c a t e d that the gene for resistance in W D R - B 1 was l o c a t e d on c h r o m o s o m e 4D. Data f r o m the noncritical crosses were h o m o g e n e o u s and pooled. The F 2 and BC1F 1 segregations o f noncritical crosses fit 3:1 and 1:1 ratios, r e s p e c t i v e l y (Table 2). Ten susceptible F 2 plants o f CS m o n o - 4 D / W D R - B 1 were cyt o l o g i c a l l y verified as n u l l i s o m i c s (Table 3). These results fit the e x p e c t a t i o n that all susceptible (recessive) F 2 plants f r o m the critical cross are n u l l i s o m i c s (Khush 1973). These c y t o l o g i c a l o b s e r v a t i o n s c o n f i r m e d the c o n c l u s i o n that the l o c a t i o n o f the gene for resistance in W D R - B 1 is c h r o m o s o m e 4D. W D R - B 1 was resistant o n l y to culture 111-SS2 a m o n g ten different stem rust cultures w h e n tested by R i e d e et al. (1995). G e n e s for stem rust resistance l o c a t e d on chrom o s o m e 4D have not been r e p o r t e d previously. Thus, w e p r o p o s e the s y m b o l Sr41 for this gene.
M o n o s o m i c analysis o f W D R - C 2 Significant d e v i a t i o n s f r o m d i s o m i c ratios t o w a r d s m o n o s o m i c ratios were o b s e r v e d in both F 2 and BC1F 1 o f CS m o n o - 5 A / W D R - C 2 and CS m o n o - 7 A / W D R - C 2 when tested with culture 111-SS2 (Table 4). T h e s e results indicated that the gene in W D R - C 2 was either on c h r o m o s o m e
1160 Table 1 Infection types produced by two cultures of stem rust, Puccinia graminis f. sp. tritici, on the parental wheat cultivars and monogenic lines Cultivar or line
Waldron WDR-B 1 WDR-C2 WDR-E4 WDR-F1 Little Club Chinese Spring
Cultures and infection types a 111-SS2
Orllc
; 23 12 12;1 = 34 34
; 34 21 2 ll34 34
a Necrotic flecks; 1, small, necrotic pustules; 2, small- to medium sized pustules with chlorosis; 3, medium-sized chlorotic pustules; 4, large pustules without cblorosis
Table 2 Segregation for seedling reaction to culture 111-SS2 of Puccinia graminis f. sp. tritici among F 2 and backcross-F1 seedlings from crosses of monogenic wheat line WDR-B1 (Sr 41) with 'Chinese Spring' monosomics (R resistant, S susceptible)
Chromosome
Number of seedlings R
Probability
S
F2 Monosomic 4D Disomic 4D Pooled noncritical crosses
379 109 2327
52 30 726
(Z2, 3R:IS) < 0.01 0.03-0.05 0.10-0.20
BC1F 1 Monosomic 4D Disomic 4D Pooled noncritical crosses
33 12 257
6 11 216
()~2, 1R:IS) < 0.01 0.80-0.90 0.05-0.10
Table 3 Distributions among classes for meiotic chromosome number and pairing of susceptible F 2 plants derived from crosses of wheat lines WDR-B1, WDR-C2, and WDR-F1 with 'Chinese Spring' monosomics susceptible to Puccinia graminis f. sp. tritici culture 111-SS2 Cross
CS CS CS CS
mono-4D/WDR-B 1 mono-7A/WDR-C2 mono-4B/WDR-C2 mono-6B/WDR-F1
tion f r o m a d i s o m i c ratio t o w a r d s a m o n o s o m i c ratio was o b s e r v e d only in the F 2 d e r i v e d f r o m CS m o n o - 7 A / W D R C2 (Table 4). The F 2 segregation in CS m o n o - 5 A / W D R C2 fits a 3:1 ratio. T h e s e results i n d i c a t e d that the gene for resistance in W D R - C 2 was l o c a t e d on c h r o m o s o m e 7A. C y t o l o g i c a l o b s e r v a t i o n s s h o w e d that 11 s u s c e p t i b l e (recessive) F 2 seedlings f r o m CS m o n o - 7 A / W D R - C 2 were n u l l i s o m i c s as e x p e c t e d for a critical cross (Table 3). M i totic c h r o m o s o m e n u m b e r and the reaction to stem rust o b s e r v e d in b a c k c r o s s - F 1, ' C S ' / / C S m o n o - 5 A / W D R - C 2 seedlings s h o w e d that a m o n g plants with 42 and 41 chrom o s o m e were both resistant and susceptible seedlings and that the gene for resistance in W D R - C 2 was not on chrom o s o m e 5 A (Table 5). The e x p e c t a t i o n s for the BC1F 1 are that resistant plants should be d i s o m i c s (42') and susceptible ones m o n o s o m i c s (41') (Khush 1973). The gene in W D R - C 2 l o c a t e d on c h r o m o s o m e 7 A cond i t i o n e d resistance to six o f ten stem rust cultures when tested b y R i e d e et al. (1995). The gene in W D R - C 2 m a y be the same as the one d e s i g n a t e d SrWld2 b y M c V e y and Roelfs (1978), b e c a u s e they p r o d u c e similar infection types w h e n tested with stem rust test cultures.
Chromosome number a 20"
20" + 1'
21"
10 11 0 3
0 0 3 0
0 0 0 0
a 20" = 20 bivalent chromosomes, 20" + 1' = 20 bivalents + 1 univalent, 21" = 21 bivalent chromosomes
5 A or on 7A. The segregation for r e a c t i o n in the F 2 f r o m d i s o m i c F 1 plants o f these 2 crosses fit 3:1 ratios (Table 4). The p o o l e d data from non critical crosses fit a 3:1 ratio for the F 2 and a 1:1 ratio for the BC1F a (Table 4). S e e d l i n g s f r o m CS m o n o - 5 A / W D R - C 2 and CS m o n o 7 A / W D R - C 2 were tested with culture O r l l c that was used p r e v i o u s l y in the selection of this m o n o g e n i c line f r o m W D R - s e l . / ' L C ' (Riede et al. 1995). A significant d e v i a -
M o n o s o m i c analysis o f W D R - E 4 Significant deviations from d i s o m i c ratios t o w a r d s m o n o somic ratios were o b s e r v e d in both the F 2 and BC1F 1 o f CS m o n o - 2 A / W D R - E 4 and CS m o n o - 5 B / W D R - E 4 when tested with culture 111-SS2. These results i n d i c a t e d that the gene in W D R - E 4 was either on c h r o m o s o m e 2 A or 5B. The segregation o f the F 2 f r o m d i s o m i c F 1 plants o f CS m o n o - 5 B / W D R - E 4 also s h o w e d a significant d e v i a t i o n f r o m a d i s o m i c ratio. The p o o l e d data for non critical crosses fit a 3:1 for the F 2 and a 1:1 ratio for the b a c k c r o s s F~ (Table 6). S e e d l i n g s fi'om CS m o n o - 2 A / W D R - E 4 and CS m o n o 5 B / W D R - E 4 were also tested with culture O r l lc. A significant d e v i a t i o n f r o m a d i s o m i c ratio t o w a r d s a m o n o somic ratio was o b s e r v e d only in the F 2 d e r i v e d f r o m CS m o n o - 2 A / W D R - E 4 . The F 2 s e g r e g a t i o n in CS m o n o 5 B / W D R - E 4 fit a 3:1 ratio (Table 6). C y t o l o g i c a l analysis o f root tips o f BC1F 1 ' C S ' / / C S m o n o - 2 A / W D R - E 4 and ' C S ' / / C S m o n o - 5 B / W D R - E 4 i n d i c a t e d that the gene in W D R - E 4 was on c h r o m o s o m e 2 A and not 5B (Table 5). The gene in W D R - E 4 l o c a t e d on c h r o m o s o m e 2 A cond i t i o n e d resistance to ten different cultures of stem rust when tested by R i e d e et al. (1995). This gene is p r o b a b l y the same as the one d e s i g n a t e d S r W I d l b y M c V e y and Roelfs (1978) that is effective against most North A m e r i can isolates o f stem rust and against stem rust cultures in other areas o f the w o r l d (Australia, Brazil, India, M e x i c o , Pakistan, and Turkey).
M o n o s o m i c analysis o f W D R - F 1 Significant d e v i a t i o n s f r o m d i s o m i c ratios t o w a r d s m o n o somic ratios were o b s e r v e d in both the F 2 and BC1F 1 o f
1161 Table 4 Segregation for seedling reaction to cultures 111SS2 and Orl lc of Puccinia graminis f. sp. tritici among F 2 and BCIF 1 seedlings from crosses of monogenic line WDR-C2 with 'Chinese Spring' monosomics (R resistant, S susceptible)
Table 5 Distribution among classes for mitotic chromosome number and reactions to Puccinia graminis f. sp. tritici of BCIF l wheat seedlings derived from crosses of lines WDR-C2, WDR-E4, and WDR-F1 with 'Chinese Spring' monosomics (R resistant, S susceptible)
Chromosome
Probability
Test culture
R
S
F2 Monosomic 5A Monosomic 7A Disomic 5A Disomic 7A Pooled non-critical crosses Monosomic 5A Monosomic 7A
261 556 124 25 1575 94 46
26 108 35 6 537 30 4
(Z2, 3R:IS) < 0.01 < 0.01 0.30-0.50 0.30-0.50 0.50-0.70 0.80-0.90 < 0.01
11 I-SS2 111-SS2 111-SS2 111-SS2 111-SS2 Orl lc Orl lc
BC1F 1 Monosomic 5A Monosomic 7A Disomic 7A Pooled non-critical crosses
48 27 8 180
6 7 5 149
(jr2, 1R:IS) < 0.01 < 0.01 0.70-0.80 0.05-0.10
111-SS2 111-SS2 11 t-SS2 111-SS2
Cross
Chromosome number and reaction 42'
41'
Culture 40'
R
S
R
S
R
S
CS//CS mono-6B/WDR-F1
9 3 4 11 11 6 5 4 7 4 t1
4 2 0 0 0 4 4 5 1 5 0
2 0 0 0 0 0 2 2 1 0 0
0 1 5 5 5 0 1 1 0 1 0
0 0 0 0 0 0 0 0 0 0 0
0 0 0 1 1 0 0 0 0 0 0
Chromosome
Number of seedlings
CS//CS mono-5A/WDR-C2 CS//CS mono-2A/WDR-E4
CS//CS mono-5B/WDR-E4
CS//CS mono-5B/WDR-F1
Table 6 Segregation for seedling reaction to cultures 111SS2 and Orl lc of Puccinia graminis f. sp. tritici among F 2 and BC1F 1 wheat seedlings from crosses of monogenic line WDR-E4 with 'Chinese Spring' monosomics (R resistant, S susceptible)
Number of seedlings
BC1F1 Monosomic 2A Monosomic 5B Pooled non-critical crosses
C S m o n o - 5 B / W D R - F 1 and C S m o n o - 6 B / W D R - F 1 w h e n t e s t e d w i t h c u l t u r e 1 1 1 - S S 2 . T h e s e results i n d i c a t e d that the g e n e in W D R - F 1 w a s e i t h e r on c h r o m o s o m e 5B or 6B. T h e F 2 d a t a f r o m d i s o m i c F 1 plants o f C S m o n o - 5 B / W D R F1 d e v i a t e d s i g n i f i c a n t l y f r o m a 3:1 ratio, b u t w a s s i m i l a r
Probability
Test culture
R
S
354 274 112 1782 238 223
32 23 14 623 51 75
(Z2, 3R:IS) < 0.01 < 0.01 < 0.01 0.30-0.50 < 0.01 0.95-0.98
111-SS2 111-SS2 111-SS2 111-SS2 Orl Ic Orl lc
6 5 121
(~2, 1R:IS) < 0.01 0.01-0.02 0.20-0.30
111-SS2 111-SS2 111-SS2
F2 Monosomic 2A Monosomic 5B Disomic 5B Pooled non-critical crosses Monosomic 2A Monosomic 5B
111-SS2 Orllc 111-SS2 111-SS2 Orllc 111-SS2 111-SS2 Orllc 111-SS2 Orllc 111-SS2
21 17 138
to a 15:1 ratio. A p p a r e n t l y , C S m o n o - 5 B / W D R - F 1 m a y b e t r a n s m i t t i n g the g e n e for r e s i s t a n c e in W D R - F 1 a b n o r m a l l y or the c r o s s w a s s e g r e g a t i n g for a s e c o n d g e n e f o r r e s i s t a n c e . T h e s e results i n d i c a t e d that c h r o m o s o m e 6B p r o b a b l y c a r r i e d the g e n e for r e s i s t a n c e in W D R - F 1 . T h e
1162 Table 7 Segregation for seed-
ling reaction to cultures 111SS2 and Orl lc of Puccinia graminis f. sp. tritici among F 2 and BC~F1 wheat seedlings from crosses of monogenic line WDR-F1 with 'Chinese Spring' monosomics (R resistant, S susceptible)
Chromosome
Numbers of seedlings R
Probability
Test culture
S
Monosomic 5B Monosomic 6B Disomic 5B Disomic 6B Monosomic 5B Monosomic 6B
281 372 136 62 73 87
18 23 10 23 19 6
(Z2,3R:IS) < 0.01 < 0.01 < 0.01 0.50-0.70 0.30-0.50 < 0.01
111-SS2 111-SS2 111-SS2 111-SS2 Orllc Orllc
BCIF 1 Monosomic 5B Monosomic 6B Pooled non-critical crosses Monosomic 5B Monosomic 6B
33 27 194 9 12
7 3 176 3 0
(•2, 1R:IS) < 0.01 < 0.01 0.30-0.50 0.05-0.10 < 0.01
111-SS2 111-SS2 111-SS2 Orl lc Orl lc
F2
p o o l e d data f r o m non critical crosses did not fit a 3:1 ratio. The data f r o m the non-critical crosses were h o m o g e nous but were deficient in the o b s e r v e d n u m b e r o f seedlings in the susceptible class w h e n c o m p a r e d to a 3:1 ratio. The p o o l e d BC1F 1 data from the non critical crosses fit a 1:1 ratio (Table 7). T h e F z and B C 1 F 1 f r o m CS m o n o - 5 B / W D R - F 1 and CS m o n o - 6 B / W D R - F 1 were tested with culture O r l lc. A significant d e v i a t i o n f r o m a d i s o m i c ratio t o w a r d s a m o n o s o m i c ratio was o b s e r v e d o n l y in the cross with m o n o s o m i c 6B. T h e s e results i n d i c a t e d that c h r o m o s o m e 6B carried the gene for resistance to stem rust present in W D R - F 1 . The segregating p o p u l a t i o n s f r o m crosses o f W D R - F 1 and W D R - E 4 with CS m o n o - 5 B s h o w e d large deficiencies o f s u s c e p t i b l e plants ( c o m p a r e d to a 3:1 ratio) when tested with culture 111-SS2 but fitted a 3:1 ratio when tested with culture O r l l c . The same single plant o f the CS m o n o - 5 B parental line was used for crosses with both W D R - F 1 and W D R - E 4 . This plant o f CS m o n o - 5 B m a y have carried a gene for resistance effective against culture 111-SS2 and ineffective against O r l l c . C y t o l o g i c a l observations s h o w e d that 3 susceptible (recessive) F2 seedlings f r o m CS m o n o - 6 B / W D R - F 1 were n u l l i s o m i c s (Table 3) and 11 d i s o m i c seedlings were resistant (Table 5), as e x p e c t e d for a critical cross. W D R - F 1 was resistant to five out of the ten cultures of stem rust used in tests b y R i e d e et al. (1995). T h e gene present on c h r o m o s o m e 6B of W D R - F 1 r e a c t e d s i m i l a r l y to S r l l l o c a t e d on c h r o m o s o m e 6B b y Knott (1959) and is p r o b a b l y the same gene. A b o u t 50% o f the ' W a l d r o n ' plants tested b y M c V e y and Roelfs (1978) carried Sr11. The c h r o m o s o m a l l o c a t i o n s o f four genes for stem rust resistance d e r i v e d f r o m the spring w h e a t cultivar ' W a l d r o n ' were d e t e r m i n e d b y m e a n s o f a m o n o s o m i c analysis. Ratio analyses a c c o m p a n i e d b y c y t o l o g i c a l e x a m i n a t i o n s o f segregating p o p u l a t i o n s s h o w e d that single genes for resistance to stem rust in w h e a t lines W D R - B 1, W D R - C 2 , W D R - E 4 , and W D R - F 1 were l o c a t e d on chrom o s o m e s 4D, 7A, 2A, and 6B, respectively. This k n o w l -
e d g e o f the c h r o m o s o m a l locations will enable geneticists, breeders, and p a t h o l o g i s t s to m o r e easily relate the genes for resistance in ' W a l d r o n ' to other k n o w n genes for resistance and i n c o r p o r a t e t h e m into new cultivars.
References Anderson MK, Williams ND, Maan SS (1971 ) Monosomic analysis of genes for stem rust resistance derived from 'Marquis' and 'Reliance' wheats. Crop Sci 11:556-558 Bedo Z, Sutka J, Bocsa E, Balla L (1979) Location of stem rust resistance in the wheat variety 'Arthur' using monosomic analysis. Cereal Res Commun 7:191-199 Belling J (1921) On counting chromosomes in pollen mother cells. Am Nat 55:573-574 Dyck PL, Kerber ER (1977) Chromosome location of gene Sr29 for reaction to stem rust. Can J Genet Cytol 19:371-373 Hanson WD (1959) Minimum family sizes for the planning of genetic experiments. Agron J 51:711-715 Khush GS (1973) Cytogenetics of aneuploids. Academic Press, New York Knott DR (1959) The inheritance of stem rust resistance. IV. Monosomic analysis of rust resistance and some other characters in six varieties of wheat including 'Gabo' and 'Kenya Farmer'. Can J Plant Sci 39:215-228 Kosner J, Bartos P (1982) Monosomic analysis and study of inheritance of resistance to stem rust in wheat cultivar 'Kavkaz'. Sbor U V T I Z - Genet a Slecht 18:101-108 Kuspira J, Unrau J (1959) Theoretical ratios and tables to facilitate genetic studies with aneuploids I. F 1 and F 2 analysis Can J Genet Cytol 1:267-312 Law CN, Worland AJ (1972) Aneuploidy in wheat and its use in genetic analysis. Plant Breeding Institute Annual Report, Cambridge, pp 25-65 Mather K (1963) Two class segregation. In: Mather K (ed) The measurement of linkage in heredity. Methuen & Co, London, pp 13-31 McVey DV, Roelfs AP (1978) Stem rust resistance of the cultivar 'Waldron'. In Ramanujam S. (ed) Proc 5th Int Wheat Genet Symp. Indian Society of Genetics and Plant Breeding, New Delhi, pp 1061-1065 Morris R, Sears ER (1967) The cytogenetics of wheat and its relatives. In: Quisenberry KS, Reitz LP (ed) Wheat and wheat improvement. (Agronomy series, vol 13). 13: American Soc of Agronomy, Madison, Wisc., pp 19-87
1163 Riede CR, Williams ND, Miller JD (1985) Inheritance of resistance to stem rust in the wheat cultivar 'Estanzuela Dakuru'. Crop Sci 25:623-626 Riede CR, Williams ND, Miller JD (1995) Wheat lines monogenic for resistance to stem rust from wheat cultivar 'Waldron'. Theor Appl Genet 90:1164-1168 Roelfs AR McVey DV (1974) Races of Puccinia graminisf, sp. tritici in the USA during 1973. Plant Dis Rep 58:608-611 Roelfs AR Long DL, Casper DH (1983) Races of Puccinia graminis f. sp. tritici in the Unites States and Mexico in 1981. Plant Dis 67:82-84
Sears ER (1954) The aneuploids of common wheat. Mo Agric Exp Stn Res Bull, p 572 Smith GS (1978) Changes in North Dakota hard red spring wheat varieties, 1900-1977. N D Farm Res, No 35:16-21 Stakman EC, Stewart DM, Loegering WQ (1962) Identification of physiologic races ofPuccinia graminis var. 'tritici'. USDA, ARS E617 Williams ND, Miller JD (1982) Inheritance of resistance to stem rust in a selection of the wheat cultivar 'Waldron'. Crop Sci 22: 1175-1179
9 Springer-Verlag 1995
C. R. Riede 9N. D. Williams - J. D. Miller. L. R. Joppa
Chromosomal location of genes for stem rust resistance derived from 'Waldron' wheat
Received: 9 June 1994 / Accepted: 18 June 1994
A b s t r a c t The chromosomal locations of genes for resistance to stem rust (Puccinia graminis Pers.: Pets. f. sp. tritici Eriks. & E. Henn.) in the wheat (Triticum aestivum L.) cultivar 'Waldron' (WDR) were determined by monosomic analyses. Wheat lines WDR-B 1, -C2, -E4, a n d - F l , w h i c h have single genes for resistance to stem rust derived previously from WDR sel. 'Little Club', were crossed onto a complete set of 21 'Chinese Spring' monosomics. The F 2 and backcross-F 1 (BC1F 1) seedlings from each of the 84 crosses were tested for reaction to culture 111-SS2 (CRLLCBB) of stem rust, and a few selected segregants were analyzed cytologically for chromosome number. The F 2 from 2 crosses of WDR-C2, -E4 and -F1 and the BC1F 1 from 2 crosses of WDR-F1 were tested also with culture Or 1 lc (CRL-QBCN). Significant deviations from disomic ratios towards monosomic ratios in the F 2 and BC1F 1 were used to determine which chromosomes carried the genes for resistance. Cytological analyses of certain BCIF 1 and susceptible F 2 plants were used to help identify the location of the genes for rust resistance. WDR-B 1 has a gene, herein designated Sr41, for resistance on chromosome 4D. WDR-C2 has a gene on chromosome 7A that may be the same as one previously designated SrWld2. WDR-E4 has a gene on chromosome 2A, possibly SrWldl, which is effective against most or all North American stem rust cultures. WDR-F1 has a gene on chromosome 6B that is the same as or similar to S r l l .
Communicated by G. E. Hart C. R. Riede ([]) Instituto Agron6mico do Paranfi-IAPAR/CNPq,Cx. Postal 1331, 86001-Londrina-PR, Brazil N. D. Williams 9J. D. Miller. L. R. Joppa Agricultural Research Service, USDA, RO. Box 5677, SU Stn., Fargo, ND 58105, USA This paper is a contribution of the North Dakota Agricultural Experiment Station, Agricultural Research Service, U.S. Department of Agriculture, Journal series No. 2165
Key words Triticum aestivum 9Puccinia graminis 9 Aneuploid 9 Cytogenetics 9Monosomics
Introduction Stem rust of wheat (Triticum aestivum L.) caused by Puccinia graminis Pers.: Pets. f. sp. tritici Eriks. and E. Henn is a serious disease that can severely reduce the yield and quality of a wheat crop. The epidemics caused by race 56 in 1935 and race 15B from 1950 to 1954 resulted in severe losses. The major method for control of stem rust has been through the breeding of resistant cultivars using race specific genes for resistance. The hard red spring wheat cultivar 'Waldron' (WDR) was grown extensively in North Dakota for many years (Smith 1978). 'Waldron' has shown a high level of resistance to infections of the stem rust fungus. Resistance is exhibited in both seedling and adult plants and extends to both prevalent and nonprevalent races of the rust population in North America (Williams and Miller 1982). Inheritance studies indicated that WDR possesses one, two, or four effective genes for resistance to stem rust, depending upon the culture of stem rust used (Williams and Miller 1982). Through selection of wheat lines monogenic for resistance from WDR, Riede et al. (1995) showed that WDR has at least six genes for resistance to stem rust. McVey and Roelfs (1978) determined that WDR was heterogeneous for reaction to certain rust cultures. Based on reactions to stem rust cultures, they indicated that about 50% of the WDR plants they tested possessed S r l l , and 20-25% possessed Sr5. Also, they found a dominant gene tentatively designated SrWldl that appeared to give resistance to most or all North American isolates of stem rust. Another gene tentatively designated SrWld2 gave resistance to a limited number of rust isolates. Roelfs et al. (1983) surveyed the occurrence of stem rust in the United States and Mexico in 1981. Their data indicated that there was no virulence in bulked urediospore collections from seedlings with SrWldl.
t159 A n e u p l o i d a n a l y s e s have been a d v o c a t e d b y several authors ( K u s p i r a and U n r a u 1959; L a w and W o r l a n d 1972; M o r r i s and Sears 1967; Sears 1954) and used to locate gene(s) on w h e a t c h r o m o s o m e s by m a n y others ( A n d e r s o n et al. 1971; B e d o et al. 1979; D y c k and K e r b e r 1977; K o s ner and Bartos 1982). The s e g r e g a t i o n ratio for a trait cond i t i o n e d b y a gene on the m o n o s o m e o f a m o n o s o m i c plant d e p e n d s u p o n the t r a n s m i s s i o n rate o f the m o n o s o m e in m a l e and f e m a l e gametes. F o r d o m i n a n t , m o n o g e n i c resistance, only the n u l l i s o m i c p r o g e n y o f a selfed critical m o n o s o m i c plant w o u l d be susceptible, and the p r o p o r t i o n o f s u s c e p t i b l e offspring w o u l d be l o w e r than e x p e c t e d for a d i s o m i c ratio o f non-critical m o n o s o m i c s . Thus, deviating s e g r e g a t i o n ratios can be used to locate genes to specific c h r o m o s o m e s . H o w e v e r , the p r o c e d u r e requires cyt o l o g i c a l e x a m i n a t i o n s to identify the c h r o m o s o m a l constitution of plants, e s p e c i a l l y the p a r e n t a l and F 1 plants. Six w h e a t lines h a v i n g single genes for resistance to stem rust were s e l e c t e d f r o m s e g r e g a t i n g generations f r o m ' W D R ' s e l . / ' L i t t l e C l u b ' (LC) (Riede et al. 1995). The location o f W D R genes for stem rust resistance on specific c h r o m o s o m e s will p r o v i d e v a l u a b l e i n f o r m a t i o n that m a y be u s e d b y geneticists, pathologists, and p l a n t breeders. F o u r o f the six m o n o g e n i c lines were used in crosses to the ' C h i n e s e S p r i n g ' (CS) m o n o s o m i c s . The o b j e c t i v e was to d e t e r m i n e the c h r o m o s o m a l l o c a t i o n s o f genes for resistance to stem rust in the four lines.
Materials and methods Wheat lines having single genes derived from 'WDR' for resistance to cultures of races 111 and 151 of the stem rust fungus (P. graminis f. sp. tritici) were studied by means of aneuploid analysis. The seeds of parental cultivars WDR (C.I. 13958), 'LC' (C.I. 4066), and 'CS' (C.L 6322) were obtained from seedstocks at the North Dakota Agricultural Experiment Station, Fargo, N. D. The monosomic lines of 'CS', developed by E.R. Sears (1954), were obtained from L.R. Joppa, Fargo, N. D. Four monogenic lines designated WDR-B 1, WDR-C2, WDR-E4, and WDR-F 1 that were developed from progenies of WDR sel./'LC' (Riede et al. 1995) were crossed as male parents to 21 lines, each monosomic for a different chromosome of 'CS'. Monosomic (2n = 20" + 1') and disomic (2n = 21") Fls were selfed and backcrossed onto euploid 'CS' (2n = 21"). Two other monogenic lines developed from 'WDR' sel./'LC', WDR-A1 and WDR-D1, will be evaluated later. A root tip squash technique was used for initially determining the number of chromosomes of the female parents and B C 1F1 seedlings. Root tips were treated in a saturated solution of l-bromonaphthalene for 4-5 h, fixed in Farmer's solution overnight, hydrolyzed in 1 M HC1 at 60-70~ for 10 min and stored in 70% ethanol. Chromosome counts were made on root tips stained in leuco-basic-fuchsin and aceto-carmine and squashed between a glass slide and a coverglass. Aceto-carmine smears of pollen mother cells (PMCs) (Belling 1921) were used to verify the chromosome number of the parents before their use in crosses. The F 2 and BCIF 1 seedlings were tested for their reaction to the stem rust fungus (P. graminis f. sp. tritici). The number of seedlings required for an accurate differentiation between a disomic and monosomic ratio was calculated by methods given by Hanson (1959). Approximately 150 F 2 and a minimum of 10 BC 1F1 seedlings from each monosomic F 1 family were tested. The stem rust inoculum was obtained from urediospore cultures of P. graminis f. sp. tritici maintained in liquid nitrogen at the North
Dakota Agricultural Experiment Station, Fargo, N. D. Culture 111SS2 (CRL-LCBB) (Roelfs and McVey 1974) had reddish-brown urediospores and culture Orl lc (CRL-QBCN) had orange urediospores. The methods of inoculation and scoring of the stem rust reaction have been described previously (Riede et al. 1985). Phenotypes were recorded in terms of infection types as described by Stakman et al. (1962). Significant deviations from disomic ratios toward monosomic ratios were used to identify the specific chromosomes that carried the genes for resistance. The exact monosomic ratio depends on the transmission rate of the univalent chromosome and varies with environment and among the 21 different monosomic lines (Khush 1973; Morris and Sears 1967). Chi-squarc tests were used for analyzing data from segregating populations. The chi-square test for heterogeneity was used to determine if the results of non critical crosses could be pooled (Mather 1963). Cytological analysis of PMCs or root tip cells in certain F 2 or backcross-FI plants was used along with reactions to stem rust to help identify the chromosomes bearing the genes for resistance.
Results and discussion The infection types o f the four m o n o g e n i c lines and parental cultivars are p r e s e n t e d on Table 1. The resistant d o n o r cultivar ' W a l d r o n ' had infection type ;, w h e n tested with both cultures 111-SS2 and O r l l c , and the s u s c e p t i b l e controls ' C S ' and ' L C ' had infection t y p e 34. The four lines had distinctly resistant reactions to both cultures, with the e x c e p t i o n o f B a, w h i c h was resistant only to culture 111SS2. The results f r o m m o n o s o m i c a n a l y s e s are p r e s e n t e d as follows:
M o n o s o m i c analysis o f W D R - B 1 Significant deviations f r o m d i s o m i c ratios t o w a r d m o n o s o m i c ratios were o b s e r v e d in the p r o g e n y o f CS m o n o 4 D / W D R - B 1. T h e s e results i n d i c a t e d that the gene for resistance in W D R - B 1 was l o c a t e d on c h r o m o s o m e 4D. Data f r o m the noncritical crosses were h o m o g e n e o u s and pooled. The F 2 and BC1F 1 segregations o f noncritical crosses fit 3:1 and 1:1 ratios, r e s p e c t i v e l y (Table 2). Ten susceptible F 2 plants o f CS m o n o - 4 D / W D R - B 1 were cyt o l o g i c a l l y verified as n u l l i s o m i c s (Table 3). These results fit the e x p e c t a t i o n that all susceptible (recessive) F 2 plants f r o m the critical cross are n u l l i s o m i c s (Khush 1973). These c y t o l o g i c a l o b s e r v a t i o n s c o n f i r m e d the c o n c l u s i o n that the l o c a t i o n o f the gene for resistance in W D R - B 1 is c h r o m o s o m e 4D. W D R - B 1 was resistant o n l y to culture 111-SS2 a m o n g ten different stem rust cultures w h e n tested by R i e d e et al. (1995). G e n e s for stem rust resistance l o c a t e d on chrom o s o m e 4D have not been r e p o r t e d previously. Thus, w e p r o p o s e the s y m b o l Sr41 for this gene.
M o n o s o m i c analysis o f W D R - C 2 Significant d e v i a t i o n s f r o m d i s o m i c ratios t o w a r d s m o n o s o m i c ratios were o b s e r v e d in both F 2 and BC1F 1 o f CS m o n o - 5 A / W D R - C 2 and CS m o n o - 7 A / W D R - C 2 when tested with culture 111-SS2 (Table 4). T h e s e results indicated that the gene in W D R - C 2 was either on c h r o m o s o m e
1160 Table 1 Infection types produced by two cultures of stem rust, Puccinia graminis f. sp. tritici, on the parental wheat cultivars and monogenic lines Cultivar or line
Waldron WDR-B 1 WDR-C2 WDR-E4 WDR-F1 Little Club Chinese Spring
Cultures and infection types a 111-SS2
Orllc
; 23 12 12;1 = 34 34
; 34 21 2 ll34 34
a Necrotic flecks; 1, small, necrotic pustules; 2, small- to medium sized pustules with chlorosis; 3, medium-sized chlorotic pustules; 4, large pustules without cblorosis
Table 2 Segregation for seedling reaction to culture 111-SS2 of Puccinia graminis f. sp. tritici among F 2 and backcross-F1 seedlings from crosses of monogenic wheat line WDR-B1 (Sr 41) with 'Chinese Spring' monosomics (R resistant, S susceptible)
Chromosome
Number of seedlings R
Probability
S
F2 Monosomic 4D Disomic 4D Pooled noncritical crosses
379 109 2327
52 30 726
(Z2, 3R:IS) < 0.01 0.03-0.05 0.10-0.20
BC1F 1 Monosomic 4D Disomic 4D Pooled noncritical crosses
33 12 257
6 11 216
()~2, 1R:IS) < 0.01 0.80-0.90 0.05-0.10
Table 3 Distributions among classes for meiotic chromosome number and pairing of susceptible F 2 plants derived from crosses of wheat lines WDR-B1, WDR-C2, and WDR-F1 with 'Chinese Spring' monosomics susceptible to Puccinia graminis f. sp. tritici culture 111-SS2 Cross
CS CS CS CS
mono-4D/WDR-B 1 mono-7A/WDR-C2 mono-4B/WDR-C2 mono-6B/WDR-F1
tion f r o m a d i s o m i c ratio t o w a r d s a m o n o s o m i c ratio was o b s e r v e d only in the F 2 d e r i v e d f r o m CS m o n o - 7 A / W D R C2 (Table 4). The F 2 segregation in CS m o n o - 5 A / W D R C2 fits a 3:1 ratio. T h e s e results i n d i c a t e d that the gene for resistance in W D R - C 2 was l o c a t e d on c h r o m o s o m e 7A. C y t o l o g i c a l o b s e r v a t i o n s s h o w e d that 11 s u s c e p t i b l e (recessive) F 2 seedlings f r o m CS m o n o - 7 A / W D R - C 2 were n u l l i s o m i c s as e x p e c t e d for a critical cross (Table 3). M i totic c h r o m o s o m e n u m b e r and the reaction to stem rust o b s e r v e d in b a c k c r o s s - F 1, ' C S ' / / C S m o n o - 5 A / W D R - C 2 seedlings s h o w e d that a m o n g plants with 42 and 41 chrom o s o m e were both resistant and susceptible seedlings and that the gene for resistance in W D R - C 2 was not on chrom o s o m e 5 A (Table 5). The e x p e c t a t i o n s for the BC1F 1 are that resistant plants should be d i s o m i c s (42') and susceptible ones m o n o s o m i c s (41') (Khush 1973). The gene in W D R - C 2 l o c a t e d on c h r o m o s o m e 7 A cond i t i o n e d resistance to six o f ten stem rust cultures when tested b y R i e d e et al. (1995). The gene in W D R - C 2 m a y be the same as the one d e s i g n a t e d SrWld2 b y M c V e y and Roelfs (1978), b e c a u s e they p r o d u c e similar infection types w h e n tested with stem rust test cultures.
Chromosome number a 20"
20" + 1'
21"
10 11 0 3
0 0 3 0
0 0 0 0
a 20" = 20 bivalent chromosomes, 20" + 1' = 20 bivalents + 1 univalent, 21" = 21 bivalent chromosomes
5 A or on 7A. The segregation for r e a c t i o n in the F 2 f r o m d i s o m i c F 1 plants o f these 2 crosses fit 3:1 ratios (Table 4). The p o o l e d data from non critical crosses fit a 3:1 ratio for the F 2 and a 1:1 ratio for the BC1F a (Table 4). S e e d l i n g s f r o m CS m o n o - 5 A / W D R - C 2 and CS m o n o 7 A / W D R - C 2 were tested with culture O r l l c that was used p r e v i o u s l y in the selection of this m o n o g e n i c line f r o m W D R - s e l . / ' L C ' (Riede et al. 1995). A significant d e v i a -
M o n o s o m i c analysis o f W D R - E 4 Significant deviations from d i s o m i c ratios t o w a r d s m o n o somic ratios were o b s e r v e d in both the F 2 and BC1F 1 o f CS m o n o - 2 A / W D R - E 4 and CS m o n o - 5 B / W D R - E 4 when tested with culture 111-SS2. These results i n d i c a t e d that the gene in W D R - E 4 was either on c h r o m o s o m e 2 A or 5B. The segregation o f the F 2 f r o m d i s o m i c F 1 plants o f CS m o n o - 5 B / W D R - E 4 also s h o w e d a significant d e v i a t i o n f r o m a d i s o m i c ratio. The p o o l e d data for non critical crosses fit a 3:1 for the F 2 and a 1:1 ratio for the b a c k c r o s s F~ (Table 6). S e e d l i n g s fi'om CS m o n o - 2 A / W D R - E 4 and CS m o n o 5 B / W D R - E 4 were also tested with culture O r l lc. A significant d e v i a t i o n f r o m a d i s o m i c ratio t o w a r d s a m o n o somic ratio was o b s e r v e d only in the F 2 d e r i v e d f r o m CS m o n o - 2 A / W D R - E 4 . The F 2 s e g r e g a t i o n in CS m o n o 5 B / W D R - E 4 fit a 3:1 ratio (Table 6). C y t o l o g i c a l analysis o f root tips o f BC1F 1 ' C S ' / / C S m o n o - 2 A / W D R - E 4 and ' C S ' / / C S m o n o - 5 B / W D R - E 4 i n d i c a t e d that the gene in W D R - E 4 was on c h r o m o s o m e 2 A and not 5B (Table 5). The gene in W D R - E 4 l o c a t e d on c h r o m o s o m e 2 A cond i t i o n e d resistance to ten different cultures of stem rust when tested by R i e d e et al. (1995). This gene is p r o b a b l y the same as the one d e s i g n a t e d S r W I d l b y M c V e y and Roelfs (1978) that is effective against most North A m e r i can isolates o f stem rust and against stem rust cultures in other areas o f the w o r l d (Australia, Brazil, India, M e x i c o , Pakistan, and Turkey).
M o n o s o m i c analysis o f W D R - F 1 Significant d e v i a t i o n s f r o m d i s o m i c ratios t o w a r d s m o n o somic ratios were o b s e r v e d in both the F 2 and BC1F 1 o f
1161 Table 4 Segregation for seedling reaction to cultures 111SS2 and Orl lc of Puccinia graminis f. sp. tritici among F 2 and BCIF 1 seedlings from crosses of monogenic line WDR-C2 with 'Chinese Spring' monosomics (R resistant, S susceptible)
Table 5 Distribution among classes for mitotic chromosome number and reactions to Puccinia graminis f. sp. tritici of BCIF l wheat seedlings derived from crosses of lines WDR-C2, WDR-E4, and WDR-F1 with 'Chinese Spring' monosomics (R resistant, S susceptible)
Chromosome
Probability
Test culture
R
S
F2 Monosomic 5A Monosomic 7A Disomic 5A Disomic 7A Pooled non-critical crosses Monosomic 5A Monosomic 7A
261 556 124 25 1575 94 46
26 108 35 6 537 30 4
(Z2, 3R:IS) < 0.01 < 0.01 0.30-0.50 0.30-0.50 0.50-0.70 0.80-0.90 < 0.01
11 I-SS2 111-SS2 111-SS2 111-SS2 111-SS2 Orl lc Orl lc
BC1F 1 Monosomic 5A Monosomic 7A Disomic 7A Pooled non-critical crosses
48 27 8 180
6 7 5 149
(jr2, 1R:IS) < 0.01 < 0.01 0.70-0.80 0.05-0.10
111-SS2 111-SS2 11 t-SS2 111-SS2
Cross
Chromosome number and reaction 42'
41'
Culture 40'
R
S
R
S
R
S
CS//CS mono-6B/WDR-F1
9 3 4 11 11 6 5 4 7 4 t1
4 2 0 0 0 4 4 5 1 5 0
2 0 0 0 0 0 2 2 1 0 0
0 1 5 5 5 0 1 1 0 1 0
0 0 0 0 0 0 0 0 0 0 0
0 0 0 1 1 0 0 0 0 0 0
Chromosome
Number of seedlings
CS//CS mono-5A/WDR-C2 CS//CS mono-2A/WDR-E4
CS//CS mono-5B/WDR-E4
CS//CS mono-5B/WDR-F1
Table 6 Segregation for seedling reaction to cultures 111SS2 and Orl lc of Puccinia graminis f. sp. tritici among F 2 and BC1F 1 wheat seedlings from crosses of monogenic line WDR-E4 with 'Chinese Spring' monosomics (R resistant, S susceptible)
Number of seedlings
BC1F1 Monosomic 2A Monosomic 5B Pooled non-critical crosses
C S m o n o - 5 B / W D R - F 1 and C S m o n o - 6 B / W D R - F 1 w h e n t e s t e d w i t h c u l t u r e 1 1 1 - S S 2 . T h e s e results i n d i c a t e d that the g e n e in W D R - F 1 w a s e i t h e r on c h r o m o s o m e 5B or 6B. T h e F 2 d a t a f r o m d i s o m i c F 1 plants o f C S m o n o - 5 B / W D R F1 d e v i a t e d s i g n i f i c a n t l y f r o m a 3:1 ratio, b u t w a s s i m i l a r
Probability
Test culture
R
S
354 274 112 1782 238 223
32 23 14 623 51 75
(Z2, 3R:IS) < 0.01 < 0.01 < 0.01 0.30-0.50 < 0.01 0.95-0.98
111-SS2 111-SS2 111-SS2 111-SS2 Orl Ic Orl lc
6 5 121
(~2, 1R:IS) < 0.01 0.01-0.02 0.20-0.30
111-SS2 111-SS2 111-SS2
F2 Monosomic 2A Monosomic 5B Disomic 5B Pooled non-critical crosses Monosomic 2A Monosomic 5B
111-SS2 Orllc 111-SS2 111-SS2 Orllc 111-SS2 111-SS2 Orllc 111-SS2 Orllc 111-SS2
21 17 138
to a 15:1 ratio. A p p a r e n t l y , C S m o n o - 5 B / W D R - F 1 m a y b e t r a n s m i t t i n g the g e n e for r e s i s t a n c e in W D R - F 1 a b n o r m a l l y or the c r o s s w a s s e g r e g a t i n g for a s e c o n d g e n e f o r r e s i s t a n c e . T h e s e results i n d i c a t e d that c h r o m o s o m e 6B p r o b a b l y c a r r i e d the g e n e for r e s i s t a n c e in W D R - F 1 . T h e
1162 Table 7 Segregation for seed-
ling reaction to cultures 111SS2 and Orl lc of Puccinia graminis f. sp. tritici among F 2 and BC~F1 wheat seedlings from crosses of monogenic line WDR-F1 with 'Chinese Spring' monosomics (R resistant, S susceptible)
Chromosome
Numbers of seedlings R
Probability
Test culture
S
Monosomic 5B Monosomic 6B Disomic 5B Disomic 6B Monosomic 5B Monosomic 6B
281 372 136 62 73 87
18 23 10 23 19 6
(Z2,3R:IS) < 0.01 < 0.01 < 0.01 0.50-0.70 0.30-0.50 < 0.01
111-SS2 111-SS2 111-SS2 111-SS2 Orllc Orllc
BCIF 1 Monosomic 5B Monosomic 6B Pooled non-critical crosses Monosomic 5B Monosomic 6B
33 27 194 9 12
7 3 176 3 0
(•2, 1R:IS) < 0.01 < 0.01 0.30-0.50 0.05-0.10 < 0.01
111-SS2 111-SS2 111-SS2 Orl lc Orl lc
F2
p o o l e d data f r o m non critical crosses did not fit a 3:1 ratio. The data f r o m the non-critical crosses were h o m o g e nous but were deficient in the o b s e r v e d n u m b e r o f seedlings in the susceptible class w h e n c o m p a r e d to a 3:1 ratio. The p o o l e d BC1F 1 data from the non critical crosses fit a 1:1 ratio (Table 7). T h e F z and B C 1 F 1 f r o m CS m o n o - 5 B / W D R - F 1 and CS m o n o - 6 B / W D R - F 1 were tested with culture O r l lc. A significant d e v i a t i o n f r o m a d i s o m i c ratio t o w a r d s a m o n o s o m i c ratio was o b s e r v e d o n l y in the cross with m o n o s o m i c 6B. T h e s e results i n d i c a t e d that c h r o m o s o m e 6B carried the gene for resistance to stem rust present in W D R - F 1 . The segregating p o p u l a t i o n s f r o m crosses o f W D R - F 1 and W D R - E 4 with CS m o n o - 5 B s h o w e d large deficiencies o f s u s c e p t i b l e plants ( c o m p a r e d to a 3:1 ratio) when tested with culture 111-SS2 but fitted a 3:1 ratio when tested with culture O r l l c . The same single plant o f the CS m o n o - 5 B parental line was used for crosses with both W D R - F 1 and W D R - E 4 . This plant o f CS m o n o - 5 B m a y have carried a gene for resistance effective against culture 111-SS2 and ineffective against O r l l c . C y t o l o g i c a l observations s h o w e d that 3 susceptible (recessive) F2 seedlings f r o m CS m o n o - 6 B / W D R - F 1 were n u l l i s o m i c s (Table 3) and 11 d i s o m i c seedlings were resistant (Table 5), as e x p e c t e d for a critical cross. W D R - F 1 was resistant to five out of the ten cultures of stem rust used in tests b y R i e d e et al. (1995). T h e gene present on c h r o m o s o m e 6B of W D R - F 1 r e a c t e d s i m i l a r l y to S r l l l o c a t e d on c h r o m o s o m e 6B b y Knott (1959) and is p r o b a b l y the same gene. A b o u t 50% o f the ' W a l d r o n ' plants tested b y M c V e y and Roelfs (1978) carried Sr11. The c h r o m o s o m a l l o c a t i o n s o f four genes for stem rust resistance d e r i v e d f r o m the spring w h e a t cultivar ' W a l d r o n ' were d e t e r m i n e d b y m e a n s o f a m o n o s o m i c analysis. Ratio analyses a c c o m p a n i e d b y c y t o l o g i c a l e x a m i n a t i o n s o f segregating p o p u l a t i o n s s h o w e d that single genes for resistance to stem rust in w h e a t lines W D R - B 1, W D R - C 2 , W D R - E 4 , and W D R - F 1 were l o c a t e d on chrom o s o m e s 4D, 7A, 2A, and 6B, respectively. This k n o w l -
e d g e o f the c h r o m o s o m a l locations will enable geneticists, breeders, and p a t h o l o g i s t s to m o r e easily relate the genes for resistance in ' W a l d r o n ' to other k n o w n genes for resistance and i n c o r p o r a t e t h e m into new cultivars.
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1163 Riede CR, Williams ND, Miller JD (1985) Inheritance of resistance to stem rust in the wheat cultivar 'Estanzuela Dakuru'. Crop Sci 25:623-626 Riede CR, Williams ND, Miller JD (1995) Wheat lines monogenic for resistance to stem rust from wheat cultivar 'Waldron'. Theor Appl Genet 90:1164-1168 Roelfs AR McVey DV (1974) Races of Puccinia graminisf, sp. tritici in the USA during 1973. Plant Dis Rep 58:608-611 Roelfs AR Long DL, Casper DH (1983) Races of Puccinia graminis f. sp. tritici in the Unites States and Mexico in 1981. Plant Dis 67:82-84
Sears ER (1954) The aneuploids of common wheat. Mo Agric Exp Stn Res Bull, p 572 Smith GS (1978) Changes in North Dakota hard red spring wheat varieties, 1900-1977. N D Farm Res, No 35:16-21 Stakman EC, Stewart DM, Loegering WQ (1962) Identification of physiologic races ofPuccinia graminis var. 'tritici'. USDA, ARS E617 Williams ND, Miller JD (1982) Inheritance of resistance to stem rust in a selection of the wheat cultivar 'Waldron'. Crop Sci 22: 1175-1179
