Exogenous GA3 significantly improved the grain filling process and yield traits of Rht15 dwarf lines in durum wheat

The dwarfing gene Rht15 can significantly reduce plant height and improve lodging resistance, but has some negative effects on yield traits. Rht15 is a gibberellin-responsive (GAR) dwarfing gene that causes dwarfism by blocking the Gibberellin (GA) synthesis pathway in plants, and application of exogenous GA₃ can increase the plant height phenotype. The aim of this study was to investigate whether exogenous GA₃ could compensate for the negative effect of Rht15 on yield while maintaining good lodging resistance. The F₅, F₆ and F₇ lines derived from reciprocal crosses between Durox (Rht15 donor) and Langdon were used to explore the response of Rht15 to exogenous GA by comparing the effects of Rht15 dwarf lines, Rht15 dwarf lines-GA₃ and tall lines on grain filling related traits, yield traits, plant height and lodging resistance traits in durum wheat. The results showed that exogenous GA₃ could significantly improve the grain filling dynamics, significantly increase the maximum grain filling rate (G_max) and the average grain filling rate (G_ave), and advance the occurrence time of maximal grain-filling rate (T_max) earlier. The 1000-kernel weight and grain yield of the Rht15 dwarf lines with-GA₃ were significantly increased and were not significantly different from the tall line. Plant height and internode length of the Rht15 dwarf lines increased significantly after exogenous GA₃ treatment, but were still slightly shorter than those of the tall lines. The lodging resistance of the Rht15 dwarf lines-GA₃ was reduced, but still had significant advantages over the tall lines. This study provided a new idea for dwarf breeding: using plant hormones to improve the negative effects of dwarfing genes on wheat.