The expression of chlorophyll (Chl) b deficiency in the y9y9 virescent soybean mutant depends strongly on the light intensity during plant growth. The mutant phenotype (high Chl a Chl b ratios, low chlorophyll content per leaf area and low chlorophyll to carotenoid ratios) is expressed at moderate to high intensities, whereas at low light intensities mutant and wild-type plants are indistinguishable. Expression of the mutation appears to be developmentally controlled and is manifested at the membrane level by inhibition of assembly/incorporation of the peripheral complement of the Chl a b light-harvesting complex II (LHC II-peripheral). Analysis of thylakoid membrane polypeptides by SDS-polyacrylamide gel electrophoresis revealed the presence of novel polypeptides of 12-15 kDa in the y9y9 mutants. These polypeptides were the most abundant protein in the thylakoid membrane when the mutation was fully expressed ( Chl a Chl b = 8) but were largely absent both from the mature wild-type and from the fully developed y9y9 chloroplasts ( Chl a Chl b = 3.5). The relative concentration of polypeptides in the 12-15 kDa region was inversely proportional to that of LHC II, suggesting a role for these novel proteins in the assembly of the LHC II and/or chloroplast development.
- (Soybean chloroplast)
- Chlorophyll b deficiency
- Light harvesting complex II assembly
- Photosynthetic unit size
- Thylakoid membrane polypeptide
ASJC Scopus subject areas
- Cell Biology