The DG1 gene in sorghum enhances lower floret fertility through epigenetic regulation, enabling double-grain spikelets that increase yield and hold promise for both crop improvement and liquor production.
The development of floret and spikelet architecture is central to grain yield in grasses, with species-specific variations influencing fertility. Sorghum typically forms two-floret spikelets, of which only the upper floret is fertile. In this study, researchers from Chinese Academy of Sciences, Sun Yat-sen University, China Agricultural University, University of Chinese Academy of Sciences and Syngenta Group China identified a major genetic locus, DG1, that enhances fertility in the normally sterile lower floret, promoting the formation of double-grain spikelets. A natural chromosomal paracentric inversion upstream of DG1 increases its expression by reducing repressive histone modifications, thereby activating lower floret meristem activity. DG1, a WUSCHEL (WUS)-like homeobox gene, mirrors similar regulatory roles seen in maize and Arabidopsis, particularly in floret meristem initiation and development. Although DG1 does not affect inflorescence meristem size, its targeted influence on floret primordia leads to a significant increase in grain number and a moderate yield boost of 10.1–12.4%, despite a slight reduction in individual grain size due to resource competition.
The functionality of DG1 aligns with the broader WUS–CLV regulatory pathway known to control meristem maintenance across species. The observed phenotypes in sorghum—comparable to rice tg1 mutants—further validate the role of WUS-like genes in enhancing grain productivity. Interestingly, while double-grain structures often include one underdeveloped grain, lines with enhanced DG1 expression can produce two mature, albeit smaller, grains per spikelet. This trade-off between grain size and number offers new strategies for high-yield breeding, particularly when combined with other grain size-related loci like qGW1 and qTGW1a. Beyond food, the double-grain trait also aligns well with industrial needs—especially in Chinese liquor production—where smaller grain size improves fermentation efficiency. This positions DG1 as a key target in both agricultural and industrial breeding programs.
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Reference:
Zhang D, Tang S, Chen J, Liu F, Zhao K, Kang L, Li C, Xia R, Yang F, Yu F, Duan CG, Xie P, Xie Q. Chromosomal inversion at the DG1 promoter drives double-grain spikelets and enhances grain yield in sorghum. Nat Plants. 2025 Mar;11(3):453-467. PMID: 40069576. doi: 10.1038/s41477-025-01937-7. Read more