Research Progress on Dwarf Genes in Soybean

Soybean is an important crop that can be used as both food, oil and forage in the world, and its yield is directly related to national food security and the sustainable development of agriculture. Plant height is a key yield component in plant type, significantly affects the formation of pod numbers per plant, the optimization of planting density, the improvement of lodging resistance and the exploration of yield potential through the synergistic effect of the number of main stem nodes and the length of internodes. Although major food crops such as rice and wheat have achieved a leap in yield through the breeding of semi-dwarf varieties and triggered a "green revolution", the per-unit yield of soybean has remained stagnant for a long time. This highlights the urgency of mining the semi-dwarf genes and analyzing their molecular mechanisms in soybean breeding research. This review systematically reviews the genetic basis and molecular regulatory network of the main stem node number and internode length among the constituent factors of soybean plant height. On the one hand, comprehensively summarizes the stem growth habit control genes specific to soybean plant types and the molecular pathways they are located in, mainly including the expression characteristics of Dt1 and Dt2 genes in the apical meristem and their regulatory effects on the growth habits of determinate, semideterminate and indeterminate types, and explore the correlation between different stem growth habits and ecological adaptability; At the molecular regulatory level, a complex regulatory network centered on Dt1 and Dt2 genes is formed in the apical meristem of soybean, integrating multiple genes and multiple signaling molecules to regulate the plant height in soybean. On the other hand, the latest research progress on the regulation of soybean plant height by the key plant hormone signaling pathways such as gibberellin, auxin and brassinosterol was reviewed. The research on the gibberellin pathway mainly focuses on the molecular mechanisms of biosynthesis, metabolic regulation and signal transduction, while brassinosterol has been found to significantly increase yield potential through the regulation of plant structure. Based on the unique plant type characteristics and the complexity of the genome in soybean, the review further looks forward to the potential paths of semi-dwarf soybean breeding and yield increase from the perspective of molecular design breeding, with the aim of providing a certain theoretical basis for genetic improvement and germplasm innovation of soybean using semi-dwarf genes.