Screening For Sources And QTL Mapping Of Resistance To Common Cutworm (Spodoptera Litura) In Soybean

With the development of society,people’s demand for pollution-free green food and the consciousness of environmental protection are growing.Insect-resistant soybean[Glycine Max(L.)Merr.]breeding is an important approach to pest control and protecting the environment.There are many kinds of soybean pests in South China,often cause serious economic losses.Spodoptera litura is one of the major pests of soybean in the region.Soybean resistance to insect belongs to quantitative traits and the phenotypic characterization is influenced by environment.So on the basis of phenotypic and insect resistance soybean breeding is difficult.If we could find the main QTL for insect-resistant and use marker-assisted selection breeding,we will greatly improve the accuracy and efficiency of choice.This study was based on the predecessors,76 varieties of representative resistant and susceptible,from the National Center for Soybean Improvement were used for rearing common cutworm.Common cutworm was reared in the laboratory by artificial diet,the newly hatched larva of S.litura reared in insectarium as tester,larva weight were weighed at 6th,9th,12th day.We took resistance varieties Lamar,PI 227687,PI 229358,"Japan" and 74906-08,susceptible varieties JLNMH,TSBPHDJ,Wenfeng 5,Nannong 89-29 and 94-156 as standard control,and then turn them into membership index value.The membership index values of larvae weight at different feeding duration were used for 76 insect resistance soybean.Based on leave loss percentage as the antixenosis index to choose the species of soybean resistance from 20 antibiosis soybeans and 20 antixenosis soybeans.Combine antibiosis with antixenosis to screen stability resistance accession.The recombinant inbred line population NJRILY was hybridized by Lamar×Nannong 1138-2,and including 326 lines.The population was used to rear common cutworm using the same way,and larva weight was weighed at 6th,9th day.To determine QTL associated with soybean insect resistance QTL,Cartographer and QTL Network software was used based on the genetic linkage map.The main results are as follows:1.The membership index value of the spring and summer landrace 76 copies ranged between-0.4 to 2.3.The joint ANOVA of three feeding duration’s showed that there existed significant difference among different feeding duration and accession,accession and feeding duration interactions showed also significant difference.Testes,and feeding duration showed also significant difference.,and there existed significant difference among accession and testes interactions,but no significant difference among tests、accession and feeding-duration interactions.Five highly resistant soybean Lamar,"Japan",PI227687,P64 and Kefeng 1 were finally selected.2.Forty soybeans form antibiosis test were selected in the antixenosis index of leave loss percentage.The results showed 6 highly resistant accession:Lamar,HNHD,ZYHZM,"Japan",Bethol,Nannong 87-23.Combined with antibiosis and antixenosis,Lamar and "Japan" were selected for both high resistance.3.The membership index value of larvae weight of NJRILY population as resistance index to determine QTL using QTL Cartographer.Three QTLs of 6th rCCW4-37,rCCW7-46 and rCCW7-102 were mapped on Chr 4,7,and explaining the variation rate of 3.25%,3.51%and 14.33%,in total,these accounted for 21.09%.Seven QTLs of 9th were rCCW2-30,rCCW4-16,rCCW4-36,rCCW4-86,rCCW7-46,rCCW7-102 and rCCW7-117 were mapped on Chr 2,4,7,and explaining the variation rate of 3.34%,3.09%,3.81%,2.92%,3.03%,17.74%and 8.63%,in total,these accounted for 42.56%.Thus the position results of 9th were more than 6th,and explain the total phenotypic variation rate of 9th was 21.47%higher than 6th.4.Compared the mapping results of QTL Cartographer software with QTL Network software,more QTLs were detected from former than latter.The common mapping results of 6th was rCCW7-102.The common mapping results of 9th were rCCW4-36 and rCCW7-102,and the common mapping results of 6th.9th was rCCW7-102.Explain the total phenotypic variation rate of QTL Cartographer software was higher than the latter.The QTL’s position is 49.9cM on the M linkage group,Komatsu et al(2005)reported CCW-1 was flanked with Satt567(33.5 cM).Therefore,Chr 7(LG M)is important for resistance to insects in soybean.QTL was hoped to use in molecular marker-assisted breeding,and it will promote soybean insect breeding.