Gene Mapping Of Wheat Lesion Mimic And Seedling Architecture

Lesion mimic and seedling growth habits are closely related to the high yield and stress resistance of wheat varieties.A naturally mutated lesion mimic family line lm452was found in the near isogenic line constructed from wheat varieties Xinong 1376 and Kehan 21.This study investigated the occurrence process of lesion mimic,physiological and biochemical characteristics,agronomic traits,environmental factors,genetic segregation,and gene mapping of lm452.In this study,we also constructed a genetic segregation population using the near isogenic lines of Xinong 1376 and Lumai 23,which are both prostrate（g225）and erect（g281）families at seedling stage.We screened molecular markers closely linked to prostrate genes at seedling stage in F_3:4and F_4:5populations.The main results are as follows:1.Analysis of physiological and biochemical characteristics and gene mapping of lesion mimic mutant lm452In the process of occurrence,the mimic lesion first occurs in the first leaf,with the color gradually changing from white to yellowish brown,in the form of striped patches;The number of lesion mimic gradually increases with plant growth and development,and can spread to the leaf sheath.Mimic lesions are affected by environmental factors,and shading can prevent or alleviate the occurrence of mimic lesions;Low temperature and strong light can aggravate the occurrence of lesion.Physiological and biochemical analysis showed that the activities of catalase（CAT）and superoxide dismutase（SOD）in lm452 were extremely significantly increased compared to the normal phenotypic sister line g451;The content of malondialdehyde（MDA）and hydrogen peroxide（H₂O₂）increased significantly;The soluble protein（SP）content significantly decreased.This indicates that the formation of lesion is accompanied by superoxide production,decreased soluble protein content,and decreased cell activity.In terms of agronomic traits,the 1000-grain weight of lm452 was significantly lower than that of g451 under both field and greenhouse conditions.A phenotypic investigation was conducted on the F₁,F₂,and F_2:3populations of lm452 and g451 hybrids.Chi-square test showed that the lesion mimic trait of lm452 was controlled by a single recessive nuclear gene.We builded DNA and RNA banks,then used BSR-Seq and BSA+660k chip technology to locate the lesion mimic gene in 6DS.In the target segment,the polymorphic SNP between lm452 and g451 was selected and KASP markers were designed with reference to the Chinese Spring Reference Genome Version 2.1.Exchange individuals were selected by using KASP high-throughput genotyping technology and homozygous lesion mimic individuals from F₂and F_2:3populations.lm452 was located at the proximal end of 6DS.A genetic linkage map was constructed using Joinmap 4.0 software,and the closely linked KASP marker lm-854 was 1.0 c M from the target gene.2.Mapping of plant architecture genes in wheat seedling stageA genetic segregation population was constructed using near isogenic lines of prostrate（g225）and erect（g281）at seedling stage,and the tillering angle was measured using a crop angle stem diameter meter.The results showed that the tillering angle grade of F₂population at seedling stage obeyed the normal distribution,indicating that the prostrate and erect growth habits at seedling stage were controlled by quantitative trait locus.Based on previous gene mapping,this study continued to screen polymorphic KASP markers in the mapping region,and used these markers to genotype individuals with extreme prostrate at seedling stage in F_3:4and F_4:5populations to screen exchange individuals;A linked marker BSRL-132（16273817）was screened on 5DS.