| Tartary buckwheat is a cold-resistant and drought-resistant crop widely cultivated in high altitude areas.High yield with high flavonoids content in seeds is a major target of genetic improvement.Mapping QTL for important traits of tartary buckwheat,mining candidate genes in QTL intervals will facilitate the study of genetic variation mechanism of the tested traits and development of the closely linked molecular markers with QTL for molecular marker-assisted breeding.A recombinant inbred lines(SJ-RILs)population,including 221 lines derived from a cross of“Small rice buckwheat×Jinqiao2”in tartary buckwheat,was used to evaluated for the genetic variation of flavonoids content in seeds,plant height,number of branches,1000-seed weight,seed length-width ratio,seed length,seed width,seed projection area,seed perimeter,seed diameter,seed roundness and seed yield.The relationship between flavonoids content in seeds and agronomic traits was explored by correlation analysis.The relationships between seed yield and yield related was analyzed by grey relational analysis.The influences of environment and genotype on tested traits were verified by two-factor variance analysis.Difference in the tested traits among lines with different seed color or shell type was analyzed.Cluster analysis was carried out based on the phenotypic data of investigated traits to screen the excellent lines.QTL mapping and analysis for all the tested was carried out based on the high density SNP genetic linkage map.The details were as follows:1.Genetic variation of the tested traits in SJ-RILs PopulationIn three years,the 1000-seed weight,seed length-width ratio,seed length,seed width,seed projection area,seed perimeter,seed diameter and seed roundness of“Jinqiao2”were significantly higher than those of“Small rice buckwheat”,the roundness of seed was significantly lower than that of“Small rice buckwheat”,and the number of branches had no difference with“Small rice buckwheat”.Two-factor ANOVA of genotype and environment of various traits in SJ-RILs population showed that environment had extremely significant influence on other 8 traits except seed length,seed width,seed length-width ratio and seed roundness.Except the number of branches,there were significant genotypic differences in the other 11 traits.The flavonoids content in seeds of the SJ-RILs population ranged from 1.34%to 3.13%with the coefficient variation of 9.61%to 12.37%.The coefficient of variation of yield traits ranged from 4.59%to 25.45%,in which seed yield was the largest,followed by 1000-seed weight,and seed roundness was the smallest.The tremendous transgressive segregation for flavonoids content in seeds and agronomic traits was observed in the population.2.Screening excellent lines with high flavonoids content and high yield in SJ-RILs PopulationIn three years,there was no significant correlation between flavonoids content in seeds and agronomic traits;Seed yield was positively correlated with 1000-seed weight,seed length,seed width,seed projection area,seed perimeter and seed diameter;The grey correlation between agronomic traits and seed yield was plant height,1000-seed weight,seed perimeter,seed projection area,number of branches,seed length,seed diameter,seed width,seed length-width ratio,seed roundness.Cluster analysis based on phenotypic values of various traits found that six lines,SJ-140,SJ-148,SJ-167,SJ-213,SJ-202 and SJ-207,were significantly higher in seed yield and 1000-seed weight,seed length,seed area,seed perimeter and seed diameter than their parent Jinqiao2 in at least two years.The seed yield ranges from 1957.08 kg/hm~2 to 2277.84kg/hm~2,which can be used for breeding of tartary buckwheat varieties with high yield.The content of flavonoids in seeds of the three lines,SJ-67,SJ-72 and SJ-190 were significantly higher than that of the male parent Jinqiao2 in two years.The content of flavonoids in seeds ranged from 2.39%to 2.60%,which could be used as a recommended material for breeding buckwheat varieties with high flavonoids in seeds.3.QTL mapping and analysis for all tested traits in SJ-RILs PopulationBased on the high density SNP genetic map,97 QTLs were detected for the tested traits,with LOD values ranging from 2.55 to 43.31 and phenotypic contribution rates ranging from 1.21%to 55.57%.These 97QTLs were distributed all the eight linkage groups,among which 79.20%QTL were located on chromosome 1.These 97 QTLs were integrated into42 QTL regions according to their peaks and confidence intervals,of which 14 QTL regions could be repeatedly detected in different years for the same trait or different traits.Block8799~Block8802 segments located on chromosome 4 was a stable locus for flavonoid content in seeds and1000-seed weight including 11 functional annotated gene,of which two were related to the synthesis of seed flavonoid content.The Block337~Block339 segments on chromosome 1 was a major QTL locus for seed shell type with 40.24%of the phenotypic contribution rate,which also controlled the seed diameter,seed area and 1000-seed weight,and five genes with functional annotation located in the segment.The Block894~Block895 segments on chromosome 1 was another major locus for seed length,seed width,length to width ratio and seed roundness,explaining 13.68%~51.76%of the phenotypic variation,the phenotypic contribution rate ranged and there were five genes with functional annotation in the segment. |
