Gma-miR1508a confers dwarfing, cold tolerance, and drought sensitivity in soybean

Cold stress is a major abiotic factor that inhibits soybean (Glycine max (Linn.) Merr.) yield. MicroRNAs (miRNAs) are prevalent endogenous gene regulators in eukaryotes that can cleave target messenger RNAs and play essential roles in soybean cold response. In this study, 105 genes, including 22 pentatricopeptide repeat (PPR) genes and 4 growth-related genes, were predicted to be the target genes of soybean miRNA miR1508a (gma-miR1508a). The expression of gma-miR1508a was induced by cold treatment but inhibited by drought stress. Compared to the wild type (WT), the overexpression of gma-miR1508a in soybean plants resulted in dwarfing and thick cell walls. Gma-miR1508a transgenic plants exhibited cold tolerance at the germination and young seedling stages, and soluble sugar content was 58.7% higher than that of WT plants under cold stress. The gma-miR1508a transgenic lines showed lower survival rates and greater leaf water loss compared to the WT under drought treatment, which indicated that gma-miR1508a reduced drought resistance in soybean. Transcript abundances of 2 PPR and 4 growth-related predicted target genes decreased in gma-miR1508a transgenic plants. In the above six genes, the expression patterns of Glyma.16G162100 (PPR) and Glyma.17G065400 (xyloglucan endo-trans-glucosylase/hydrolase, XTH) showed opposite trends with gma-miR1508a under cold conditions. 5 '-Rapid amplification of complementary DNA ends (5 '-RACE) assays of Glyma.16G162100 revealed that the cleavage sites of gma-miR1508a are located at the 15th and 21st nucleotides of the complementary region. This study demonstrated that gma-miR1508a confers dwarfing, cold tolerance, and drought sensitivity in soybean.