Researchers have identified a key gene that mediates the effects of photoperiod and UV-B radiation on isoflavonoid accumulation in soybean seeds, shedding light on how seasonal changes in the natural light environment affect soybean seed quality.

Isoflavonoids are an important class of secondary metabolites in soybean. They are involved in physiological processes such as plant disease resistance, microbial interactions, abiotic stress responses, and nodule formation, and also have important nutritional and health benefits for humans.

Although the molecular mechanisms underlying isoflavonoid biosynthesis in soybean seeds have been studied to some extent, it remains unclear how changes in the light environment associated with seasonal variation regulate isoflavonoid content in soybean seeds under natural conditions.

Recently, a research team led by Professor HOU Xingliang from the South China Botanical Garden (SCBG) of the Chinese Academy of Sciences (CAS) identified a key gene, ICR1, that regulates isoflavonoid content in soybean seeds. The findings were published in The Plant Cell.

The study revealed that photoperiod signals regulate isoflavonoid accumulation through the GmCOL2b-ICR1 molecular module, whereas UV-B radiation promotes ICR1 accumulation by enhancing the stability of the ICR1 protein.

A molecular model illustrating the regulation of isoflavonoid accumulation in soybean seeds by the light environment. (Image by ZHANG Chunyu)

According to the researchers, this study not only provides valuable genetic resources for the genetic improvement of soybean quality, but also elucidates the molecular mechanism by which a shortening photoperiod and changes in UV radiation synergistically promote isoflavonoid accumulation in soybean seeds during the summer-to-autumn seasonal transition.

HOU's team has focused on soybean seed development and environmental adaptability, and has made a series of important research advances. This study further reveals the molecular mechanism through which changes in the light environment promote the accumulation of secondary metabolites in soybean seeds.

The study was co-first authored by postdoctoral researcher JIAN Mingyang and doctoral student WU Huan from SCBG, with Professor HOU and Associate Professor ZHANG Chunyu from SCBG serving as co-corresponding authors.

The research was supported by the Natural Science Foundation of Guangdong Province, the National Natural Science Foundation of China, and the National Key Research and Development Program.