Dwarfing gene Rht18 from tetraploid wheat responds to exogenous GA₃ in hexaploid wheat

Yang, Z.Y. and Liu, C.Y. and Du, Y.Y. and Chen, L. and Chen, Y.F. and Hu, Y.G. (2017) Dwarfing gene Rht18 from tetraploid wheat responds to exogenous GA₃ in hexaploid wheat. Cereal Research Communications, 45 (1). pp. 23-34. ISSN 0133-3720

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Abstract

Rht18, derived from Triticum durum (tetraploid) wheat, is classified as a gibberellic acid (GA)-responsive dwarfing gene. Prior to this study, the responses of Rht18 to exogenous GA on agronomic traits in hexaploid wheat were still unknown. The response of Rht18 to exogenous GA₃ on coleoptile length, plant height, yield components and other agronomic traits were investigated using F_4:5 and F_5:6 hexaploid dwarf lines with Rht18 derived from two crosses between the tetraploid donor Icaro and tall Chinese winter wheat cultivars, Xifeng 20 and Jinmai 47. Applications of exogenous GA₃ significantly increased coleoptile length in both lines and their tall parents. Plant height was significantly increased by 21.3 and 10.7% in the GA₃-treated dwarf lines of Xifeng 20 and Jinmai 47, respectively. Compared to the untreated dwarf lines, the partitioning of dry matter to ears at anthesis was significantly decreased while the partitioning of dry matter to stems was significantly increased in the GA₃-treated dwarf lines. There were no obvious changes in plant height and dry matter partitioning in the GA₃-treated tall parents. Exogenous GA₃ significantly decreased grain number spike^–1 while it increased 1000-kernel weight in both the dwarf lines and tall parents. Thus, applications of exogenous GA₃ restored plant height and other agronomic traits of Rht18 dwarf lines to the levels of the tall parents. This study indicated that Rht18 dwarf mutants are GA-deficient lines with impaired GA biosynthesis.

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