Global warming has an impact on crop growth and development. Flowering time is particularly sensitive to environmental factors such as day length and temperature. In this study, we investigated the effects of global warming on flowering using an open-top Climatron chamber, which has a higher temperature and CO₂ concentration than in the field. Two different soybean cultivars, Williams 82 and IT153414, which exhibited different flowering times, were promoted flowering in the open-top Climatron chamber than in the field. We more specifically examined the expression patterns of soybean flowering genes on the molecular level under high-temperature conditions. The elevated temperature induced the expression of soybean floral activators, GmFT2a and GmFT5a as well as a set of GmCOL genes. In contrast, it suppressed floral repressors, E1 and E2 homologs. Moreover, high-temperature conditions affected the expression of these flowering genes in a day length-independent manner. Taken together, our data suggest that soybean plants properly respond and adapt to changing environments by modulating the expression of a set of flowering genes in the photoperiod pathway for the successful production of seeds and offspring.

Soybean [Glycine max (L.) Merr.] is an excellent source of protein, oil, carbohydrates and many other bioactive ingredients for humans. However, several antinutritional and allergenic components such as lipoxygenase, KTI, lectin, 7S α′ subunit, and stachyose exist in the raw mature seed. Genetic removal of these components would be the best method to improve soybean food quality. The objectives of this research were to breed a new soybean line with penta null recessive alleles (lox1/lox1/lox2/lox2/lox3/lox3-ti/ti-le/le-cgy1/cgy1-rs2/rs2) for these five components and to evaluate agronomic traits for a breeding line with penta null alleles. Seven germplasms were used to breed the penta null strain. Analysis of lipoxygenase, KTI, lectin, 7S α′ subunit, and stachyose components in mature seeds was conducted by SDS-PAGE, western blot, and HPLC. One breeding line with penta null recessive alleles was developed. The breeding line has purple flowers, tawny pubescence, a determinate growth habit, and light yellow pods at maturity. The seed of the breeding line has a yellow hilum and yellow seed coat color. The stem height of the breeding line was 53.0 cm. The stachyose content of the breeding line was 2.9 g/kg. The 100-seed weight of the breeding line was 31.1 g and yield (t/ha) was 2.80. This is the first soybean strain with the penta null (lox1lox2lox3/lox1lox2lox3-ti/ti-le/le-cgy1/cgy1-rs2/rs2) genotype (free of lipoxygenase, KTI, lectin, and 7S α′ subunit proteins, and with low stachyose content).

Anthocyanins from the black soybean seed coat are known to have many pharmaceutical effects. However, black soybean seed contains antinutritional factors such as lipoxygenase, Kunitz trypsin inhibitor (KTI), lectin, and stachyose. The genetic removal of these components will improve the nutritional value of black soybean seed. The objective of this research was to breed a soybean strain with the black seed coat color, green cotyledon color, and tetra recessive allele (lox1lox2lox3/lox1lox2lox3-ti/ti-le/le-rs2/rs2) for lipoxygenase, KTI, lectin, and stachyose components. Eight parents were used to breed the tetra null strain. Analysis of lipoxygenase, KTI, lectin, and stachyose components in mature seeds was conducted by SDS-PAGE, Western blot, and HPLC. The soybean line with the black seed coat color, the green cotyledon color, a large seed size, and tetra recessive alleles has purple flowers, a determinate growth habit, and brown pods at maturity. The stem height of the breeding line was 52.3 cm. The 100-seed weight of the breeding line was 35.2 g and the yield (Ton/ha) was 2.50. The stachyose content of the breeding line was 3.30 g/kg. This is the first soybean strain with the black seed coat color, the green cotyledon color, a large seed size, and tetra null alleles (lox1lox2lox3/lox1lox2lox3-ti/ti-le/le-rs2/rs2, low content of stachyose, free of lipoxygenase, KTI, and lectin proteins).