Relationship between Photosynthesis and Chlorophyll Content during Leaf Senescence of Rice Seedlings |
| |
Authors: | Kura-Hotta, Mariko Satoh, Kazuhiko Katoh, Sakae |
| |
Affiliation: | Department of Pure and Applied Sciences, College of Arts and Sciences, University of Tokyo 153, Japan |
| |
Abstract: | Photosynthetic oxygen evolution, chlorophyll contents and chlorophylla /b ratios of 3rd to 6th leaves of rice seedlings were measuredto examine whether or not inactivation of photosynthesis duringsenescence is related to loss of chlorophyll. Photosyntheticactivity decreased more rapidly than chlorophyll content duringleaf senescence; as a result, the lower the leaf position, thelower was the rate of oxygen evolution determined on the basisof chlorophyll. Chlorophyll a b ratio also decreased with advancingsenescence. Electrophoretic analysis revealed that the declinein chlorophyll a b ratio is due to more rapid degradation ofthe reaction center complexes than light-harvesting chlorophylla b proteins of photosystem II and that the photosystem I reactioncenter disappears in parallel with the inactivation of photosynthesis.A simple method was developed to estimate the amounts of chlorophylla associated with the reaction center complexes of the two photosystemsfrom the total chlorophyll contents and chlorophyll a b ratiosof leaves. Rates of oxygen evolution, determined on the basisof chlorophyll a bound to the reaction center complexes, remainedconstant throughout the course of senescence. Thus, inactivationof photosynthesis is closely related with loss of the reactioncenter complexes during leaf senescence of rice seedlings. Theresults suggest that loss of photosynthesis is mainly causedby loss of a functional unit of photosynthesis or by a decreasein the number of whole chloroplasts. (Received April 22, 1987; Accepted August 13, 1987) |
| |
Keywords: | |
本文献已被 Oxford 等数据库收录! |
|