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Analysis of Rice Mutants by Low Temperature‐Derivative Spectrophotometry in Relation to Pigment Compositions and Photochemical Activities
Author(s) -
INOUE YORINAO,
OGAWA TERUO,
KAWAI TAKESHI,
SHIBATA KAZUO
Publication year - 1973
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1973.tb04836.x
Subject(s) - photosystem i , chloroplast , photosystem ii , chlorophyll , chlorophyll b , p700 , photosystem , photochemistry , chemistry , chlorophyll a , photosynthesis , photosynthetic reaction centre , biology , biochemistry , botany , gene
The chloroplasts of five rice ( Oryza sativa ) mutants examined in the present study possessed the following pigment and activity characteristics as compared with those of normal strain (Nohrin No. 8); a) less chlorophylls (especially, chlorophyll b , the molar ratio of a to b = 6 ∼ 41) and less carotenoids but higher ratios of β‐carotene to chlorophylls; b) only photosystem 1 particles were obtained by density gradient centrifugation of digitonin‐treated mutant chloroplasts while both photosystem 1 and 2 particles were obtained from normal strain chloroplasts; c) the photosystem 2 activities of mutant chloroplasts were lower (48 ∼ 81 %) than that of normal chloroplasts while their photosystem 1 activities were 1.9 ∼ 2.4 times higher. The derivative absorption spectrum of the normal chloroplasts ( a/b = 4) measured at liquid nitrogen temperature showed many small but distinct maxima and minima in the red region in addition to those observable for chlorophylls in solution. These band structures including the French inflection were lost partially in the derivative spectra of three mutants with a/b = 6, 8 and 11 and almost completely in those of the remaining two mutants with a/b = 18 and 41. The lack of such band structures reflecting specific states of chlorophylls in vivo was attributed to the absence of some conformational structures such as those expected in photosystem‐2 particles, which are formed by the presence of chlorophyll b and are resistant to the digitonin treatment. Chlorophylls in specific states in such structures were thought to exhibit a higher photosystem 2 activity.