Soybean gene editing technology boosts high yields in the south

According to the latest news from the Chinese Academy of Agricultural Sciences, the Plant Transgenic Technology Research Center and the Soybean Breeding Technology Innovation and New Variety Selection and Breeding Innovation Team of the Institute of Crop Sciences of the academy used CRISPR/Cas9 genome editing technology to precisely knock out the key soybean flowering regulatory genes GmFT2a and GmFT5a, creating mutant materials more suitable for cultivation in low-latitude regions; at the same time, they systematically analyzed the genetic effects of the GmFT2a and GmFT5a genes in the regulation of soybean flowering time, providing new technology and new materials for the regional adaptability improvement of soybean varieties. The related research results were recently published online in the Plant Biotechnology Journal.

Han Tianfu, team leader and researcher at the Institute of Crop Sciences of the Chinese Academy of Agricultural Sciences, introduced that soybean is sensitive to photoperiod response. For the vast majority of varieties, only after the day length shortens to a certain limit can they transition from vegetative growth to reproductive growth and then flower and set pods; as a result, when soybean varieties are planted northward, they often flower and mature late, with an extended growth period, and may even fail to flower or mature normally; when planted southward, they generally show excessively early flowering, a shortened growth period, reduced yield, and may even fail to grow normally. This photoperiod response characteristic makes the suitable cultivation areas for soybean varieties generally rather narrow. Previous studies have shown that the GmFT2a and GmFT5a genes are important flowering-promoting factors in soybean.

By constructing overexpression plants of the GmFT2a and GmFT5a genes and using CRISPR/Cas9 genome editing technology to precisely knock out GmFT2a and GmFT5a, combined with hybridization methods, the team created single-gene and double-gene mutant materials. Studies have shown that although GmFT2a and GmFT5a have functional complementarity in the regulation of soybean flowering time, their flowering-promoting effects differ greatly under long-day and short-day conditions. Under short-day conditions, the flowering-promoting effect of GmFT2a is stronger than that of GmFT5a, while GmFT5a has a stronger flowering-promoting effect under long-day conditions. The critical photoperiod has a great influence on soybean flowering regulation involving GmFT5a. Under conditions exceeding the critical photoperiod day length of a variety, the GmFT5a gene is the main flowering-promoting gene and the key gene enabling soybean to adapt to long-day environments. The study also found that the created double-gene mutant flowered at an average of 57.4 days under short-day conditions, about 31.3 days later than the wild type, and its plant height and node number were significantly higher than those of the wild type, while the number of pods and seeds per plant also increased significantly, providing new basic materials for the improvement of soybean varieties suitable for cultivation in low-latitude regions.