Soybean Maturity Genes Associated with Seed Coat Pigmentation and Cracking in Response to Low Temperatures

Abstract

ABSTRACTExposure of soybean [Glycine max (L.) Merr.] to chilling temperatures (≈15°C) at flowering induces browning around the hilum region and cracking of the seed coats. Both pigmentation and cracking degrade the external appearance of soybean seeds and reduce their commercial value. An earlier study showed that one of the genes responsible for pigmentation is closely associated with a maturity gene. The objective of this study was to evaluate the effect of five soybean maturity genes (E1–E5) on the intensity of seed coat pigmentation and cracking. Soybean cv. Harosoy (e1e2E3E4e5) and its near‐isogenic lines (NIL) for E1 to E5 loci were exposed to 15°C for 2 wk beginning 8 d after anthesis. Control plants were grown in a greenhouse throughout their life cycle, whereas treated plants were transferred from the greenhouse to a phytotron for the chilling treatment. Intensity of pigmentation was not affected by e3, slightly reduced by E2 and e4, and profoundly reduced by E1 and E5 Degree of cracking was slightly increased by e3 and drastically reduced by e4, E1, and E5 The results suggest that some of the soybean maturity genes have inhibitory effects on the intensity of seed coat pigmentation and cracking in response to low temperatures. Dominant alleles E1 and E5 are most effective in suppressing both pigmentation and cracking. Therefore, these two genes may be useful to ensure tolerance to chilling stress in cultivars with e3 and e4, which jointly condition the insensitivity to long daylength, an adaptive trait in high latitude regions.