PLANT PHYSIOLOGY , Vol 107, Issue 1 253-262, Copyright © 1995 by American Society of Plant Biologists
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GENE REGULATION AND MOLECULAR GENETICS |
The Impact of Chlorophyll-Retention Mutations, d1d2 and cyt-G1, during Embryogeny in Soybean
W. S. Chao, V. Liu, W. W. Thomson, K. Platt and L. L. Walling
Department of Botany and Plant Sciences, University of California, Riverside, California 92521-0124
The ultrastructural, physiological, and molecular changes in developing and
mature seeds were monitored in a control line (Glycine max [L.] Merr., cv
Clark) that exhibited seed degreening and two mutant lines (d1d2 and
cyt-G1) that retained chlorophyll upon seed maturation. Ultrastructural
studies showed that the control line had no internal membranes, whereas
stacked thylakoid membranes were detected in the green seed from the mutant
lines. Pigment analyses indicated that total chlorophyll was lowest in the
mature seeds of the control line. Mature d1d2 and cyt-G1 seed had elevated
Chl a and Chl b levels, respectively. In both control and mutant lines,
Lhcb1, Lhcb2, and RbcS mRNAs were abundant in embryos prior to cotyledon
filling, declined after the onset of storage protein accumulation, and were
barely detectable or undetectable in all later stages of seed development.
Therefore, the chlorophyll-retention phenotype must be a result of the
alteration of a process that occurs after translation of
photosynthesis-related mRNAs to stabilize apoprotein and pigment levels.
Furthermore, different elements controlling either the synthesis or
turnover of Chl a and Chl b must be impaired in the d1d2 and cyt-G1 lines.
No reproducible differences in total leaf, embryonic, and chloroplast
protein profiles and plastid DNAs could be correlated with the mutations
that induced chlorophyll retention.
