QTL Primary Mapping Of Starch Gene In Maize

Maize starch is the main component of maize grain,maize starch is the main raw material source of starch industry,which includes high amylose maize starch,high amylopectin and mixed high starch,maize starch is very important and widely used in food and industrial fields,thus become a new target for maize breeding to improve the content of maize starch in the world.Combining the traditional breeding methods with molecular marker assisted selection breeding technology,in order to provide certain theoretical basis and practical basis for the increase of starch content in maize grain.In this study,5M017 and 5D07 were used as the parents of the 110 generations of offspring of the F₂ generation segregating population as materials,we selected 200 pairs of primers distributed in 10 chromosomes of maize,with SSR molecular markers of starch with the method of composite interval mapping（total starch,amylose,amylopectin）of QTL content,the main results are as follows:1.F₂ segregating population total starch content average is 78.25%,higher than that mid parent value 75%;F₂ segregating population amylose content average value is 42.25%,lower than mid parent value 42.58%;F₂ segregating population amylopectin content average value is 64.75%,higher than the mid parent value 57.38%.The emergence of super parents separated individual plants in three kinds of starch.2.In 200 pairs of SSR primers,labeled with polymorphism between the parents is 68,polymorphism is about 30%.By QTL IciMapping Version 4.0 software with SSR marker technology,building covering 10 chromosomes of maize genetic linkage map,a total length of 1607.7cM,the average genetic distance is 23.64 cM.3.QTL analysis of three kinds of starch by using composite interval mapping method,17 QTLs were detected mainly in chromosome fourth in addition to the other 9 chromosomes.Associated with the total starch content of QTLs is 10,locating on 9 chromosomes,the contribution rate between 8.47%-25.68%;related to amylose QTLs is 5,the contribution rate between 8.29%-24.78%;related to amylopectin QTLs is 2,the contribution rate changes from 8.16 % to 17.24%.4.Total starch related loci 85.2（1）,182.6（3）,154.2（7）,160.3（8）and 140.5（10）were close to the loci previously studied and were initially identified as the same loci.At the same time,the amylose content related QTLs 98.9（3）and 164.8（6）were compared with the results of previous studies,and the location of the loci found in the database MaizeGDB was relatively close,initially identified as the same site.The other loci were initially identified as new loci,which need further verification.At the same time to detect 3 kinds of starch near sites of each one,first identified as the same loci is 11.1 loci（10）,total starch and amylose were all of a two short distance,first identified as the same loci is 160.3（8）.The results show that the loci and chromosomal regions of the marker have many overlaps with previous studies.The results are reliable and can be used for preliminary localization of QTL.