RESEARCH REPORTS
PNL Volume 11
1979
TEMPERATURE DEPENDENT BEHAVIOR OF A CHLOROPHYLL MUTANT OF PEAS
Williams, A.F,
Williams Laboratories, Williams, Indiana, U.S.A.
Four years ago, I marked a white seedling in my spring pea crop. This
plant eventually turned green, and its progeny appeared to be normal in the
fall crop. Subsequent investigation has revealed that it was homozygous for
a recessive gene which controls chloroplast pigment development in a tempera-
ture dependent manner. Homozygotes develop no photometrically detectable
chlorophyll or carotenoids when maintained at temperatures of 8°C or less,
regardless of light intensity or day length. However, exposure of very young
leaves to 20°C in light or dark for as little as 48 hr is sufficient to induce
development of near normal pigment levels after return to 8°C. The upper
three leaves on all plants in the accompanying photograph went through this
critical stage at 20°, 8°, and 20°, respectively.
Dr. Blixt has assigned type No. 222S to this mutant, and he is testing
it for allelism with other chlorophyll mutants. He informs me that some
measure of temperature dependence among many, if not most, of the known
chlorophyll mutants of peas can be inferred from his own field observations.
Fig. 1. Chlorophyll mutant showing sensitivity to temperature.
