Analysis And Location Of QTLs Related To Protein And Fat Content In Brown Rice

This article exploited the Kjeldahl nitrogen determination method,the extraction method and near infrared analyzer measurement method to carry out the assay and analysis of protein and fat content data by using the pre-existing germplasm materials,R498/R3551 recombinant inbred line population,fragment substitution lines（BC₄F₆ with R498as the reincarnation parent and Basmati as the donor parent）and other groups.The study was designed to establish the near infrared analyzer calibration model.On this basis,the population QTLs analysis and position were carried out.The main results were as follows:1.Construction of a calibration model for protein and fat content:The chemical finding showed the resource materials had a large difference in protein and fat content and followed normal distribution.The scan results through the near-infrared analyzer found that the spectral curves of the resource materials were highly variable,and the material diversity was relatively rich which was suitable for calibration models and QTLs analysis.Finally,a partial least squares method was used to construct a near-infrared spectrum and a calibration model for protein and fat content of brown rice.2.Verification of the calibration model of protein and fat content:The correlation coefficient between the protein content determined by the Kjeldahl nitrogen determination method and the protein content determined by the near infrared analyzer reached 0.93;the correlation coefficient was 0.41 between the fat content which it was determined by the Soxhlet extraction method and by the near infrared analyzer.The results showed that the near-infrared measurement was reliable and could be used for the preliminary determination of protein and fat content of brown rice.3.Analysis of the heritability of protein and fat content:The calculation results of protein content and fat content of resource materials in 2018-2019 found that the heritability of protein content reached 0.78 and the heritability of fat content reached 0.74,indicating that protein and fat content were mainly controlled by genetic factors.4.Location of protein and fat content of resource material QTLs:A total of 11 QTLs were detected by GWAS analysis of protein content of resource material in 2018-2019,as well as a total of 20 QTLs by GWAS analysis of fat content.5.Location of QTLs of protein and fat content of recombinant inbred lines:The protein and fat content were analyzed by Bin map linkage analysis to obtain 5 QTLs related to protein and fat content,which were located on chromosomes 2,6,and 12,respectively.6.Location of protein QTLs of fragment substitution lines group:Genomic resequencing and co-substitution fragment analysis found that there were two overlapping fragments in the stable lines N577 and N578 both of which were rich in high protein;there were three overlapping fragments in the stable lines N570 and N582 both of which were strongly short of protein content.These common fragments were likely QTL sited that controled protein content.7.Excavation of new QTL for protein content:The experiment of using the lines N577 that was rich in protein content and R498 to backcross builded the separate groups BC₅F₂found the substitution fragment of Chr12:2279499-3128415 was determined to be linked to the protein content,which was an unreported QTL in control of the protein content.