The Impact of Chlorophyll-Retention Mutations, d1d2 and cyt-G1, during Embryogeny in Soybean

Abstract

The ultrastructural, physiological, and molecular changes in developing and mature seeds were monitored in a control line (Glycine max [LI Merr., cv Clark) that exhibited seed degreening and two mutant lines (dld2 and cyt-C1) that retained chlorophyll upon seed maturation. Ultrastructural studies showed that the control line had no interna1 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 dld2 and cyt-Cl seed had elevated Chl a and Chl b levels, respectively. In both control and mutant lines, Lhcbl, 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 dld2 and cyt-C1 lines. N o reproducible differences in total leaf, embryonic, and chloroplast protein profiles and plastid DNAs could be correlated with the mutations that induced chlorophyll retention.

Localization and Post-translational Processing of the Wound-induced Leucine Aminopeptidase Proteins of Tomato

“…MeJA-treated and control plants were incubated for 24 h prior to tissue harvest. Chloroplasts were isolated using the method described by Chao et al (37), and total proteins were extracted. Integrity of plastids was confirmed by light microscopy.…”

Chlorophyll b Reductase Plays an Essential Role in Maturation and Storability of Arabidopsis Seeds

“…Similar observations were also reported in a soybean (Glycine max) mutant. Specifically, the soybean chlorophyllretention mutant cytG has a much higher level of chlorophyll b and elevated chlorophyll a in leaves and seeds (Guiamét et al, 1991;Chao et al, 1995). In seeds of the cytG mutant, stacked thylakoid membranes were detected (Chao et al, 1995).…”

“…Specifically, the soybean chlorophyllretention mutant cytG has a much higher level of chlorophyll b and elevated chlorophyll a in leaves and seeds (Guiamét et al, 1991;Chao et al, 1995). In seeds of the cytG mutant, stacked thylakoid membranes were detected (Chao et al, 1995). It is possible that chloroplasts are not fully converted to gerontoplasts due to the retention of LHCII and grana membranes.…”

Identification of Two Duplicated Loci Controlling a Disease‐like Rugose Leaf Phenotype in Soybean

“…Soybean is a paleopolyploid that has undergone at least two polyploid or whole genome duplication events within the last 60 million years. The d1d2 double recessive mutants inhibited chlorosis of soybean leaves, pods and, embryo, causing a mutated organism that retained the chlorophyll, called 'stay-green' (Chao et al, 1995). For example, among the four homologous genes of the Arabidopsis TERMINAL FLOWER gene (TFL1) in soybean, only one has been found to control growth habit; the other copies may have additional functions because they have shown different transcriptional patterns (Tian et al, 2010).…”