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AN ALBINO MUTANT IN PLANTAGO INSULARIS REQUIRING THIAMINE PYROPHOSPHATE—ROLE OF TPP IN PIGMENT AND PROTEIN SYNTHESIS
Author(s) -
MICHAEL SANDRA D.,
SPURR ARTHUR R.
Publication year - 1975
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1975.tb02609.x
Subject(s) - chloroplast , chlorophyll , mutant , carotenoid , biochemistry , pigment , darkness , chlorophyll b , photosynthesis , biology , nitrogen deficiency , thiamine pyrophosphate , plastid , plantago , botany , chemistry , nitrogen , cofactor , enzyme , gene , organic chemistry
SUMMARY Seedlings of Plantago insularis were grown in darkness for 5 days and then exposed to white light for 24 h. At the beginning of the light period some plants were treated with thiamine pyrophosphate (TPP). Light exposure caused a marked development of both chlorophyll a and b in the normal (al + /al + ) plant, but only a slight formation of chlorophyll in the mutant ( al/al ) TPP plus light induced the formation of chlorophyll a and b in the mutant to near normal levels. Light alone increased the level of carotenoids in the normal type, but not in the mutant; but TPP plus light increased the carotenoids in the mutant to near normal. Albinism in Plantago is due, in part, to a deficiency in TPP and a consequent deficiency in chlorophyll and carotenoid pigments. Acid‐soluble nitrogen was distinctly lower in the albino mutant than in normal plants, but increased in the mutant after treatment with TPP and exposure to light. Exposure of dark‐grown normal seedlings to light alone caused a marked increase in acid‐insoluble nitrogen. Recovery in the mutant appeared to be at the expense of the soluble nitrogen fraction, and is attributed to the synthesis of chloroplast proteins. The light‐yellow mutant grown in the dark became bleached on exposure to light, yet a moderate increase in nitrogen occurred during exposure, indicating that some protein synthesis is independent of chlorophyll and carotenoid development in the plastids. A pathway initially involving TPP appears to be affected by light in the formation of chloroplast proteins.