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Photosynthetic Capacity and Quantum Requirement of Three Secondary Mutants of Scenedesmus obliquus with Deletions in Carotenoid Biosynthesis *
Author(s) -
Bishop N. I.,
Bugla Beate,
Senger H.
Publication year - 1998
Publication title -
botanica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 0932-8629
DOI - 10.1111/j.1438-8677.1998.tb00700.x
Subject(s) - carotenoid , photosynthesis , strain (injury) , chlorophyll , mutant , biology , scenedesmus , scenedesmus obliquus , biochemistry , chlorophyll a , biosynthesis , photosynthetic capacity , botany , algae , gene , anatomy
Photosynthetic capacity and quantum requirement of photosynthesis were evaluated in three secondary mutants of Scenedesmus obliquus possessing specific blocks in carotenoid biosynthesis. These were derived from the mutant, C‐2 A', a strain which develops chlorophyll only in the light. All strains were capable of a normal and rapid production of chlorophyll and the development of a functional photosynthetic apparatus when exposed to light. LHC‐II levels in the mutants lacking the β,ε‐carotenoids (strains C‐2 A'‐34,1 and C‐2 A'‐67, 3b) were considerably reduced in fully greened cells but normal in the β,β‐epoxycarotenoid deficient‐only strain (C‐2 A'‐67,1) (Bishop, 1996). The maximum photosynthetic capacity and the quantum efficiency (at λ=682nm) of photosynthesis of cells of C‐2A'‐34,1 and C‐2 A'‐67,1 showed no significant changes when compared to the original parent strain, C‐2 A'. However, the quantum requirement of the strain lacking both types of carotenoids, C‐2 A'‐67,3b, was slightly increased. It is of particular interest that both strains lacking the β,ε ‐carotenoids also show a preferential loss of the oligomeric form of the LHC and its associated chlorophylls. The potential requirement of the different carotenoids in maintenance of photosynthetic efficiency in Scenedesmus is discussed.