• Chinese Scientists First Discovered a Key Gene Related to Sorghum Glume Coverage

    TIME: 25 Feb 2022
    In a recent study published online in Nature Communications, Chinese scientists identified a key gene involved in sorghum glume coverage during cereal domestication. This research will provide theoretical support basis for naked-grain breeding in sorghum, millet and other gramineous crops, and conducted by XIE Qi's team from the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences.
    Loss of glume coverage leads to seeds being detached from sticky glumes, which is a symbolic event in the crop threshing process and crop domestication. The hulled character carried by wild crop species can resist the invasion of animals and fungi and ensure their own reproduction. However, this hulled trait was greatly weakened during crop domestication due to inconvenient manual or mechanized grain threshing, processing and breeding. Therefore, the naked character has been selected by humans.
    Sorghum is one of the earliest cultivated gramineous crops. It has a rich phenotypic variation in glume coverage, among which the grain sorghum accessions are mostly naked (Figure 1). Scholars took glume coverage character as a typical index to distinguish sorghum subspecies eighty years ago, but the molecular basis of sorghum glume coverage remains unknown.
    Figure 1. Abundant phenotypic variations in sorghum glume coverage (Image by IGDB)
    Through the application of genetics, bioinformatics and molecular biology, the researchers from XIE’s lab demonstrated that natural variation of GC1 (glume coverage 1), a major locus, controls glume coverage in sorghum. GC1 functions as a negative regulator in sorghum glume coverage. C-terminal truncated GC1 versions may reduce their degradation mediated by the 26S proteasome, which accumulates significantly higher protein levels, resulting in reduced glume coverage.
    A patatin-related phospholipase SbpPLAII-1 functioning as a positive regulator can promote glume cell proliferation by upregulating the expression of cyclin-CDK-related genes. Compared with GC1, gc1-a, which is more stable in vivo, could promote the degradation of SbpPLAII-1 and then inhibit the function of SbpPLAII-1, resulting in a reduction in sorghum glume coverage.
    In addition, selection analysis shows that the GC1 gene was strongly domestically selected in naked sorghum cultivars. The genotype-based geographical distribution results show that the Sahel region, where the annual sorghum yield reaches 65% of total Africa, is a potential domestication center of sorghum.
    In conclusion, their study is the first to identify a key gene, GC1, controlling glume coverage and to reveal a molecular mechanism involved in glume development in sorghum. In the future, site-specific truncated mutation in GC1 will also fast achieve the rapid de novo domestication of wild cereal germplasm resources.
    Figure 2. A potential working model for GC1 controls sorghum glume coverage (Image by IGDB)
    Dr. XIE Qi
    Institute of Genetics and Developmental Biology, Chinese Academy of Sciences