Abstract:

【Objective】 Understanding the effects of wheat dwarfing genes on coleoptile length and plant height is crucial for the proper utilization of dwarfing genes in yield improvement of wheat. 【Method】 Molecular markers analysis combined with pedigree information were used to classify wheat cultivars widely used in the major wheat growing regions of China into different categories based on the dwarfing genes carried, then the effects of dwarfing genes with different response to Gibberellins (GA3) on coleoptile length and plant height were analyzed based on plant height data from the field and coleoptile length data from the lab. 【Result】 The screening of 129 cultivars with molecular markers revealed that 58 genotypes contained the dwarfing gene Rht-B1b, 24 genotypes had Rht-D1b，and 73 genotypes possessed Rht8, and among them there were 35 genotypes with two dwarfing genes Rht-B1b+Rht8，and 16 genotypes with two dwarfing genes Rht-D1b+Rht8. Test on response to GA3 of these cultivars revealed that wheat cultivars with the dwarfing genes Rht-B1b or Rht-D1b were insensitive to GA3, and those with the dwarfing gene Rht8 were responsive to GA3. Genotypes with Rht-B1b+Rht8 and Rht-D1b+Rht8 were also insensitive to GA3. The height reducing effects of GA3 insensitive dwarfing genes Rht-B1b, Rht-D1b, Rht-B1b+Rht8, and Rht-D1b+Rht8 were as 24.6%, 30.4%, 28.2% and 32.2%, respectively, while that of GA3-responsive dwarfing gene Rht8 was 14.3%. The GA3 insensitive dwarfing genes Rht-B1b, Rht-D1b, Rht-B1b+Rht8, and Rht-D1b+Rht8 also shortened the coleoptile length by 25.4%, 31.3%, 28.4%, and 31.3%, respectively, whereas the GA3-responsive dwarfing gene Rht8 only shortened the coleoptile length by 6.2%. 【Conclusion】 To summarize, the GA3 insensitive dwarfing genes Rht-B1b and Rht-D1b shorten the coleoptile length largely as well as reducing plant height and are not suitable to wheat improvement for dryland, while the GA3-responsive dwarfing gene Rht8 has much less effects on shortening coleoptile length and also could reduce plant height to some extent, it is the right dwarfing gene for wheat improvement of dry land.

Key words: bread wheat, dwarfing genes, Rht-B1b, Rht-D1b, Rht8, coleoptile length, plant height