Molecular Identification of Mutant Candidate of Gα Gene from Soybean cv. Slamet Based on mRNA.
Heterotrimeric G proteins composed of α, β, and γ subunits, are bound to the inside surface of the cell membrane. Gα proteins will be activated by extracellular stimuli (biotic or abiotic stress). It is presumably Gα proteins playing an important role in aluminum (Al)-stress tolerance. Soybean cv. Slamet was considered as a tolerant plant to Al and has a single copy of Gα gene. Gamma irradiation to soybean cv. Slamet seeds caused a random chromosomal mutation of second generation plants (designated as M2). The Gα mutant candidates were selected based on stomatal closure in the daylight and dwarf. Gα mutant candidates M4, number 338 and 103 have severe root cell tissues damage compared to non mutant ones. Plant number 338/3S1.174/12/14 (M4) and 103/3S3.103/8/5/1/4 (M5) have a Gα gene mutation at the U3-L4 sequences (exon 5 – exon 11). Whereas, plant number 344/3S1.196/14/1/8 (M4) is assumed as Gα gene mutant. All of those plants were replanted until sixth generation. The candidates of Gα mutant selected have more than fifty percent of closed stomata and dwarf. Four number of M5 plants and three number of M6 plants were selected for Gα mutant identification based on mRNA analysis. The fifth generation plant number 344/3S1.196/14/1/8/7 were decreased its Gα gene expression at L5-L4 sequences (exon 7 – exon 11). The M6 generation plant number 344/3S1.196/14/1/8/7/5 have mutation in Gα gene at L1-L3 sequences (exon 2 – exon 6). A major contributing factor to decreased expression levels of Gα gene may be due to mutation of Gα gene promotor. Three other of M5 plants were assumed as Gα mutant. M6 plant number 103/3S3.103/8/5/1/4/8 has mutation at L3-L2 sequences (exon 6 – exon 15) and number 103/3S3.103/8/5/1/4/9 has mutation at U3-L4 sequences (exon 5 – exon 11). The decreasing of gene expression caused by mutation in those plants was indicated by the less pronounced DNA bands on agarose gel than that of non mutant plants.
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