Soybean (Glycine max) is the main source of human plant protein, edible oil and animal feed protein. Cultivated soybeans are domesticated from wild soybeans. In the process of domestication and improvement of soybeans, a large number of key genes and excellent allelic variations have been lost. However, there are few genes (mainly E1, E2, E3 and E4) controlling soybean growth period and adaptability in cultivated soybeans in high latitude areas, and their genotypes are gradually fixed (mainly e1as/e2/e3/E4), severely limiting the cultivation of high-yield soybean varieties suitable for planting in this area.
There are a large number of wild soybeans distributed in Heihe City of Heilongjiang Province and the Far East of Russia. How do these wild soybeans adapt to the ecological environment in high latitude areas? In order to explore this scientific problem, research team of Kong Fanjiang/Liu Baohui of Guangzhou University has conducted long-term systematic and in-depth research for many years. They identified the Tof4 (Time of flowering 4) locus, which encodes by an E1-like protein, E1La, that represses flowering and enhances adaptation to high latitudes in wild soybean. Moreover, it was found that Tof4 physically associates with the promoters of two important FLOWERING LOCUS T (FT2a and FT5a) and with Tof5 to inhibit their transcription under long photoperiods. The effect of Tof4 on flowering and maturity is mediated by FT2a and FT5a proteins.
The results showed that the introgression of the tof4-1 and Tof5H2 alleles into modern soybean or editing E1 family genes represents promising avenues to obtain early-maturity soybean, thereby improving productivity in high latitudes.