Analysis Of QTL Controlling Oil Content In Five RIL Populations Of Brassica Napus L.

Rapeseed(Brassica napus L.)can not only give people edible plant oil that man needs every day,but also act as resource to produce fuel oil and lube oil.The target of rapeseed breeding is to improve its production,meanwhile,oil content is a vital factor that should be taken into consideration.Oil content is a complex trait that controlled by multi-genes and easily influenced by environment.So far,the genetic mechanism of oil content is to be found.To figure out it,a high oil content cultivar ZS11 was used as common male parent,and five relatively low oil content cultivar as female parents.Crossing and selfing for five generations to get five RILs(RIL1-RIL5)respectively,each RIL contains 142 to 183 lines.We planted these five RILs in five different environments and investigate the oil content of five RILs and six parents.Genetic analysis and QTL mapping for oil content are conducted.There is marked difference between the female parents of RIL1,RIL2 and RIL3 with ZS11 in oil content.The lowest parent of RILs has a 7.9 percent lower than that of ZS11 in oil content.In all environments,RILs show lowest oil content compared to other environments,and it shares a relative high variable coefficient in 15 CD.The result of two-factors variance analysis showed that oil content of five RILs is influenced by genotype effect and environment effect,and reaches a highly significant effect.The broad heritability of five RILs are all above 0.92.Five genetic linkage maps were conducted with the help of information of five RILs' reduced-representation sequencing.There are 4079-5724 SNP markers in each RIL family and the length of map ranges from 1135 to 2322.05 cM,average distance between two markers is about 0.37 cM.QTL mapping was conducted for oil content of all RILs in five environments.We noted QTLs with a LOD score larger than threshold value,and called them significant level QTL(SL-QTL).QTLs with LOD score between threshold value and 2.5,and can be identified in two or more environments,were called micro-real QTL(MR-QTL).SL-QTL and MR-QTL are identified-QTLs.A total of 116 SL-QTLs and 23 MR-QTLs were identified.We integrated these QTLs by means of a software called BioMercator 4.2.Meta-analysis was conducted to integrate overlapping QTLs.At last,68 QTLs remained and 39 of which were consensus QTLs.Consensus QTL is a QTL that can be identified in two or more environments.All these 68 QTLs distributed in A01,A02,A04,A05,A07,A08,A09,A10,C03,C05,C07 and C09 linkage group.We then finally integrated QTLs by physical confidence interval,and we got 13 QTL clusters.There is a cluster called QTL_Cluster.A05-2 in A05 linkage group.It can be identified in all five environments and four RILs except for RIL5.By blasting to the genes function pool of Arabidopsis,we found six genes related to oil content trait.