Phenotypic Analysis And Fine Mapping Of Rice Grain Shape QTL GL5

As the area of farmland decreases and the global population increases,rice(Oryza sativa L.),which is the main food source for about half of the world’s population,urgently needs to increase production.Rice is also an important model plant for studying gramineous plants.At present,the main goal of rice breeding is high yield and high quality.Rice grain type is a complex agronomic trait,which is a typical quantitative trait,controlled by multiple genes,and determines rice yield and quality plays an important role.The identification and cloning of quantitative trait loci(QTL)are of great significance in genetic research and breeding.In this study,a set of chromosome segment substitution lines constructed from the japonica rice variety Nipponbare as the donor parent and the indica rice variety 9311 as the recipient parent and recurrent parent were used in this study,and a molecular marker-assisted selection technique was used to obtain one grain substitution material GL5.Perform a positional study on a QTL GL5 that controls particle size and genetically analyze it.The results are as follows:1.By analyzing the phenotype and agronomic traits of the material GL5 and the parent 9311,it was found that compared with the recipient parent 9311,the GL5 particle length increased highly significantly,the grain width increased significantly,and the 1000-grain weight increased by 6.8 g.With the increase of plant height and spike length,there was no obvious change in the number of primary branches,and the number of secondary branches decreased significantly,resulting in a significant decrease in the number of grains per panicle.Scanning electron microscopy of glume was found to increase the number of epidermal cells in the lateral and lateral epidermis of GL5.According to quantitative data of young panicles,most of the cell cycle-related genes in GL5 were up-regulated.2.We assigned GL5 to the end of the long arm of chromosome 5 in the summer of2015,Wenjiang,we constructed the F2 segregation group and used the recessive single plant for routine gene mapping in the summer of 2016,Wenjiang.According to the change of the exchangeable individual plant,GL5 is located in the interval 586kb between AMRS2 and Y99/100.The Indel marker was further developed in the summer of 2016,and GL5 was further positioned in the 403 kb region between markers Y79/80 and Y99/100 using the fragment overlap method.There are a total of 68 genes in this interval.The candidate genes that are currently considered more likely are GL5-3、GL5-5、GL5-6、GL5-7.3.Substitution materials of NIL-GS3 and NIL-gw5 were also screened in this chromosome segment substitution line.Using these two fragment substitution materials to hybridize with NIL-GL5 respectively,through the observation of particle size of several near isogenic lines and polymeric materials,it was found that the length of NIL-GL5/GS3 was between the two parents,GL5.There was an additive effect with gw5,which resulted in a long and wide grain type after polymerization,with a significant increase in grain weight.The grain size of NIL-GS3/gw5 was short and wide,and there was no significant difference in grain weight relative to 9311.Based on the two-way analysis of variance of the grain length traits of NIL-GL5 and NIL-GS3,it was found that there may be genetic interactions between GL5 and GS3.The effects of GL5 and GS3 are different in different contexts,and the GS3 effect is stronger than GL5.4.In this research,the quality of GL5 was measured.It was found that there was no significant difference between the chalkiness and chalkiness rate of GL5 and 9311.Compared with starch SEM,there was no significant difference in the starch grain arrangement of GL5 compared with 9311.While GL5 increased in 1000-grain weight,there was no significant change in rice quality compared to 9311.GL5 and the two-line sterile lines Lu 56 s and Y58 s showed increased grain length and increased 1000-grain weight,due to the presence of GL5,the number of grains per panicle decreased,the yield also decreased,and the quality of rice did not change significantly.This is of great significance for the improvement of parents and the acquisition of large grain quality varieties for use in breeding.