Planta (Berl.) 127, 37--47 (1975) 9 by Springer-Verlag 1975

Chloroplast Fluorescence of C4 Plants III. Fluorescence Spectra and Relative Fluorescence Yields o f B u n d l e - S h e a t h a n d M e s o p h y l l C h l o r o p l a s t s * ** L y a n e E l k i n *** a n d R o d e r i c B. P a r k Botany Department and Lawrence Berkeley Laboratory Berkeley, California 94720, USA Received 21 April; accepted 30 July 1975 Summary. In situ fluorescence emission spectra of mesophyll and bundle-sheath chloroplasts of Dichauthium annulatum (Forsk.) Stapf are measured by a microscopic technique using black and white infrared film as a detector. These spectra confirm the higher ratio of infrared to far-red fluorescence in bundle-sheath relative to mesophyll chloroplasts as predicted by infrared color film observations. The total relative fluorescence yield of bundle-sheath chloroplasts is ca. half that of mesophyll chloroplasts. The fluorescence emission spectra and yields of both mesophyll and bundle-sheath chloroplasts of Dichanthium annulatum are equally affected by Tris washing. Therefore, we conclude that both chloroplast types have approximately equivalent variable components of fluorescence. This variable fluorescence component has a strong infrared component, in addition to the expected far-red component. Similarly, the relative mesophyll to bundle-sheath fluorescence yields of these chloroplasts remains almost constant after DCMT3, and after Tris followed by hydroxylamine treatments. The similar effects of the above chemical treatments on the fluorescence yields and spectra of the two chloroplast types is interpreted as evidence for the same relative proportion of photosystem I to photosystem I I in bundle-sheath and mesophyll chloroplasts.

Introduction I n this p a p e r we c o m p a r e t h e fluorescence emission s p e c t r a a n d r e l a t i v e fluorescence yields of b u n d l e - s h e a t h a n d m e s o p h y l l chloroplasts utilizing techniques d e v e l o p e d b y E l k i n a n d P a r k 1975a, b. A l l q u a n t i t a t i v e studies a r e p e r f o r m e d on Dichanthium annula~um as p r e p a r e d in E l k i n a n d P a r k , 1975b. T h e results confirm a n d e x t e n d those o b t a i n e d w i t h i n f r a r e d color film. W e also t r e a t t h e t w o chloroplast t y p e s w i t h several inhibitors of p h o t o s y s t e m I I a c t i v i t y t o determine w h e t h e r t h e r e l a t i v e p r o p o r t i o n of p h o t o s y s t e m I to p h o t o s y s t e m I I is different in b u n d l e - s h e a t h a n d m e s o p h y l l chloroplasts. Results A. Control Material

Fig. 1 presents t h e fluorescence emission s p e c t r a of Dichanthium annuIatum m e s o p h y l l a n d b u n d l e - s h e a t h chloroplasts as d e t e r m i n e d b y our t e c h n i q u e * This work was supported in part by NSF grants GB-25579X and GB-41720X and the Atomic Energy Commission, and a Sigma Xi Grant-in-Aid of Research. ** Abbreviations: DCMU= [3, (3,4-diehlorophenyl)-l,l-dimethylurea]; Tris= tris (hydroxymethyl)amino-methane. *** Submitted in partial requirement of the Ph.D. degree. Lynne Elkin was supported as an NIH Predoctoral Fellow. Present address: Department of Biological Sciences, California State University at Hayward, Hayward, California 94542, USA.

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Chlorplast fluorescence of C4 plants : III. Fluorescence spectra and relative fluorescence yields of bundle-sheath and mesophyll chloroplasts.

In situ fluorescence emission spectra of mesophyll and bundle-sheath chloroplasts of Dichanthium annulatum (Forsk.) Stapf are measured by a microscopi...
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