Identification Of New Dwarf Sources In Wheat And Genetic Effects Of Wheat Dwarf Genes Rht12 And Rht-B1b In Hexaploid Triticale

Wheat（Triticum aestivum L.）is very important to food security,and plant height is one of the important factors affecting wheat yield.At present,the main wheat dwarf genes used in production are Rht1,Rht2 and Rht8,which limit the improvement of wheat yield potential,and Rht1 and Rht2 have some adverse effects.Therefore,it is very important to utilize new dwarf genes for wheat production.In this study,a natural dwarf mutant of wheat variety Yanzhan 4110 was identified,and its effects on agronomic traits was investigated to provide reference for its application.Triticale（Triticale）is a new species obtained through interspecific hybridization of wheat and rye.In order to improve lodging resistance,triticale breeding for dwarfing has gradually been important.In this study,the wheat dwarf genes Rht12 and Rht-B1b were transferred to hexaploid triticale.After multiple generations of selection and stabilization,the effects of wheat dwarf genes Rht12 and Rht-B1b on triticale were investigated.Field agronomic character effects,analysis of the application value and potential of wheat dwarf genes in improving lodging resistance of triticale.The main results of this study are as follows:1.Genetic effect of Rht-yzYanzhan 4110 dwarf mutant is a mutant that dwarfed in the natural state of the field.This study temporarily named the mutant gene Rht-yz.Using the 660K chip and BSA strategy,analysis suggests that the mutation site of Yanzhan 4110 dwarf mutant may be located in the4B:30-33MB.The relative expression and genome sequencing results of the known wheat dwarf gene Rht-B1b in 4B:30-33MB showed that the dwarf mutation site is not the allele of Rht-B1b.Therefore,the dwarf mutants used in this study may contain new dwarf genes.The agronomic traits of Yanzhan 4110,Yanzhan 4110 dwarf mutant and their hybrid F₂and F_2:3 populations were investigated.The results showed that Rht-yz reduced plant height about 24.8%by significantly shortening the length of each internode without changing the number of internodes.At the same time,the thickness and diameter of the dwarf lines basal internode increased significantly,and the lodging resistance efficient increased significantly.Rht-yz increased the root hair system.In yield traits,Rht-yz reduced the effective tiller number and thousand-kernel weight of dwarf lines,which had a partial negative effect on yield.The crude protein content,wet gluten content and starch content of the dwarf lines were all significantly increased.2.Effect of wheat dwarf gene Rht12 on agronomic traits of hexaploid triticaleUsing molecular marker detection and chromosome number identification,it was determined that the material for this study was a stable hexaploid triticale population carrying the wheat dwarf gene Rht12,while the high-stalk line not carried.Analysis on agronomy traits showed that Rht12 reduced the plant height of triticale by about 37.7%,and the length of each internode was significantly shortened.At the same time,the diameter and thickness of the internode of the dwarf plant also increased,which was beneficial to improve the lodging resistance.The number of spikelets（17.2%）and grain number per spike（27.3%）of the Rht12dwarf line is significantly reduced,but the thousand-kernel weight,harvest coefficient,grain length,width and thickness have no significant effects.Grain quality analysis showed that in the grains of the Rht12 dwarf line,the crude protein content and the higher wet gluten grains were significantly increased by 24.5%and 15.9%.3.Effect of wheat dwarf gene Rht-B1b on agronomic traits of hexaploid triticaleUsing molecular marker detection and chromosome number identification,it was determined that the material for this study was a stable hexaploid triticale population carrying the wheat dwarf gene Rht-B1b,while the tall stalk line not carried.Analysis on agronomy traits showed that Rht-B1b reduced the plant height of triticale by about 29.9%and shortened all internodes.Rht-B1b increased the diameter thickness of internodes,which is beneficial to improve the lodging resistance of triticale.At the same time,Rht-B1b has no significant adverse effect on the yield traits of triticale and the net photosynthetic rate of flag leaf at the filling stage.Analysis of grain-related traits showed that Rht-B1b significantly reduced grain size and grain plumpness,but improved quality characteristics such as crude protein content.In summary,Yanzhan 4110 dwarfing mutant may contain an unknown dwarfing gene Rht-yz,which has a significant positive effect on wheat lodging resistance and grain quality while reducing plant height.Although some negative effects on yield,it has certain application potential and value.The wheat dwarf genes Rht12 and Rht-B1b significantly improved the lodging resistance of hexaploid triticale,but decreased the yield per plant and the plumpness of grains.Therefore,the wheat dwarf gene has the application value for enhancing the lodging resistance of hexaploid triticale,but it still needs further improvement and research in practical production.