Molecular characteristics and regulatory effects of dwarfing Rht genes in Triticum aestivum L

Application of Rht dwarfing genes has significantly enhanced plant lodging resistance and harvest index. However, the numerous members of Rht genes, particularly newly cloned genes in recent years, remain poorly understood in integrated analysis of their expression patterns under stress conditions, allelic interaction effects, and molecular regulatory mechanisms, these limit our comprehensive exploration of Rht gene regulatory network, and hinder the potential application in wheat genetic improvement.

This study comprehensively analyzed the characteristics of Rht family members. The results showed that there were 27 Rht genes in wheat, with only 10 cloned members. Collinearity of Rht genes was observed in wheat genomes, as well as cross-species collinearity. Rht1 exhibited significantly highest basal expression from roots to grain, and actively responded to phosphate stress, with markedly upregulated after 4 h treatment, achieving a maximum value of log₂ fold change = 4.02. The interaction network was centered around Rht4, Rht12, and Rht24 proteins. In 47 wheat varieties, Rht24 was more widely distributed, Rht1 + Rht2 exhibited a strong dwarfing effect, whereas showing negative impact on thousand kernel weight (TKW), and introduction of Rht12 or Rht24 can mitigate the negative effect. A stack of Rht4 + Rht8 can optimizes plant architecture, while the combination of Rht8, Rht12 and Rht24 achieves higher yields, ranging from 9150 kg·ha⁻¹ to 11,250 kg·ha⁻¹, such as cultivars SN25, SN29 and XN579. The distribution frequency of Rht5 was correlated with plant height and yield-related traits, with all correlation coefficients (r) exceeding 0.89 and false discovery rate (FDR) being less than 0.05. Rht8 and Rht12 exhibited strong correlations with plant height and TKW, respectively, with r value all exceeding 0.8.

This study systematically analyzed the regulatory relationships among Rht genes and their expression patterns under abiotic stress conditions, and evaluated the combined effects of alleles. Grey correlation analysis revealed that Rht1 and Rht5 were strongly correlated with plant height and yield-related traits. These provide theoretical support for allele combinations to breed the dwarf and high-yield wheat during molecular design breeding, such as Rht4 + Rht8 for reasonable plant type, Rht8 + Rht12 + Rht24 for favourable grain yield, thereby achieving breeding goals that balance height and stable yields.