Preliminary Mapping Of Dwarf Gene Rht15 And Its Effects On Photosynthetic Physiology And Major Agronomic Traits In Durum Wheat

Wheat is a major food crop which is important to food security,lodging is an important factor affecting wheat yield.Using dwarf genes is a critical measure to improve lodging resistance,although the widely used dwarf gene Rht1 and Rht2 have a strong height-reducing effect,they have a negative effect on early wheat vigor.Therefore,the introduction of new dwarfing genes is essential for wheat breeding.In this study,the genetic populations were constructed with the donor parent durum wheat"Durox"?Rht15?and the tall durum wheat"Langdon",the dwarf gene Rht15 was preliminarily mapped and the photosynthetic physiological traits and effects of important agronomic of durum wheat were analyzed,laying a foundation for the rational use of Rht15.The main findings are as follows.1. Preliminary mapping of dwarf gene Rht15The two F₂ populations were obtained using reciprocal crosses of Rht15 donor parent durum wheat"Durox"?Rht15?and tall durum wheat"Langdon"?Does not contain any dwarf genes?.Through the BSA strategy combined with 660K SNP chip and RNA-Seq analysis,the homozygous differential SNPs between the tall and dwarf parents-lines were screened,and specific KASP markers were screened and developed to map the Rht15.Based on the phenotypic and genotypic data analysis of the F₂ individual,the dwarf gene Rht15 was located between the 6A chromosome 6A035 and 6A031 between 2.9c M in the Durox/Langdon population,the dwarf gene Rht15 was located on the 6A chromosome6A033 and 6A031 between 6.3c M in the Langdon/Durox population.2. Genetic effects of dwarf gene Rht15The molecular markers developed by preliminary mapping were used to genotype the F₂ population,and homozygous dwarf and tall lines containing only Rht15 and no dwarf genes were selected,and F_2:3,F_3:4 and F_4:5 lines were created.The dwarf gene Rht15 was analyzed for plant height,flag leaf,seedling root,yield,and quality and photosynthetic physiological traits.Rht15 significantly reduced plant height by 29%on average,the diameter and wall thickness of internode were a certain increased by Rht15.Although Rht15dwarf lines significantly increased the flag leaf width compared to tall lines,there was no significant effect on flag leaf area.There were no adverse effects of Rht15 on coleoptile length,root surface area,root diameter and total root volume,although Rht15 decreased the maximum root length?4.5%?,root number?6.5%?and total root length?7.6%?.The dwarf gene Rht15 can significantly increase the net photosynthetic rate and chlorophyll content of flag leaves.Compared to tall lines,Rht15 dwarf lines had reduced 1000-kernal weight?15.7%?and grain number per spike?4.2%?,less biomass plant^-1?12.5%?and lower grain yield plant^-1?8.1%?,but there was no significant effect on the number of fertile tillers plant^-1and harvest index;Rht15 dwarf lines had increased grain protein content?3.3%?,wet gluten content?3.2%?and starch content?2.0%?.Taken together,the results indicate that Rht15 improves the lodging resistance of wheat,reduces plant height,and has a positive effect on photosynthetic physiological traits and quality traits.At the same time,preliminary positioning of Rht15 was completed,chromosomal positions were elucidated,and available molecular markers were developed,laying the foundation for the analysis of candidate clones and dwarf mechanisms...