Chinese Bulletin of Botany ›› 2017, Vol. 52 ›› Issue (4): 389-393.DOI: 10.11983/CBB17110

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The Genetic Basis of Soybean Extended to Tropical Regions

Yan Li, Junyi Gai*   

  1. National Center for Soybean Improvement/MOA Key Laboratory for Biology and Genetic Improvement of Soybean (General)/ National Key Laboratory of Crop Genetics and Germplasm Enhancement/Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, Nanjing 210095, China
  • Received:2017-06-01 Accepted:2017-06-06 Online:2017-07-01 Published:2017-05-05
  • Contact: Gai Junyi
  • About author:

    # Co-first authors

Abstract: Soybean (Glycine max) is a plant sensitive to photoperiod, which determines its maturity date and therefore its adaptation to respective eco-regions. The soybean varieties from temperate regions flower and mature very early in tropical regions (short photoperiod), which leads to low yields and limits the commercial cultivation of soybean in these regions. The discovery of long-juvenile (LJ) soybean varieties is a major breakthrough to overcome this problem. Under short photoperiod, the LJ soybean varieties show delayed flowering and maturity time, enhanced growth and therefore, higher yields than temperate varieties. Previous studies found that locus J had a major contribution to the LJ trait. Recently, Chinese scientists cloned the J gene by fine-mapping and found it as an ortholog of Arabidopsis thaliana EARLY FLOWERING 3 (ELF3). The functions of J gene were confirmed by transgenic complementation and near-isogenic lines: the j genotype showed later flowering and maturity date and more yield potential than the J genotype. Further studies showed that the J protein bound to the promoter of the E1 gene (a legume-specific flowering repressor) to downregulate E1 expression, thereby relieving the suppression of E1 on soybean FLOWERING LOCUS T (FT) genes, which leads to early flowering under short photoperiod. In addition, multiple j alleles and haplotypes were identified from soybean germplasm. The study leads to a new direction in genetic research of growth periods for the expansion of soybean to tropical regions.