PHOTOINHIBITION OF GROWTH OF A YELLOW AND A COLORLESS FORM OF CHLAMYDOMONAS REINHARDTII

Abstract— Long‐term growth on acetate in darkness of a permanently yellow and a white‐in‐darkness mutant of Chlamydomonus reinhardtii showed no requirement for light. Room light or moderate intensities of white light severely inhibited the white mutant, but allowed continuous growth of the yellow form. Blue light (460 nm) stops motility and growth, and induces clumping, in the white form at energy levels which only reduce the growth rate of the yellow mutant. Green light (550 nm) had no effect on either strain, while red light (630 nm), at equal energy levels, affected the white mutant only, however, not as severely as blue light. The mechanism of action of blue and red light is unknown. Evidence suggested the inhibition is not due to cell exudates. Copyright © 1969, Wiley Blackwell. All rights reserved