Locating And Excavating Of Genes On Meloidogyne Incognita Resistance In Honggengansutao 1(Prunus Kansuensis L.)

Root-knot nematode is an important disease affecting the safe production of crops in the world,and it is also an important pathogenic factor of‘short life disease’and‘replanting disease’of peach trees.Among them,Meloidogyne incognita is the most widespread and severe.Breeding resistant peach varieties is the most economical measure to control the root-knot nematode.Systematically studying the resistance gene of peach and exploring its position and function in the immune response network is helpful to understand the nature of peach disease resistance.‘Honggengansutao 1’is immune to M.incognita,and‘Bailey’is highly susceptible to M.incognita,they are the excellent germplasm to study resistance of peach to M.incognita.A lot of basic work has been done around the resistance gene of‘Honggengansutao 1’to M.incognita:a rapid identification method of resistance to root-knot nematode was established;The genetic linkage map of‘Honggengansutao 1’בBailey’with high density was constructed;Finely completed genetic localization was doing;Transcriptome spectrum of root-knot nematode infection of peach was received.Screening and mapping of resistance genes of‘Honggengansutao 1’provide an important theoretical basis for the rational use of resistant varieties and the new strategies of disease resistance breeding.In this study,302 F₂ were constructed from the parents of‘Honggengansutao 1’and‘Bailey’.The resistant and susceptible gene pools from BC₁ were constructed by BSA method.According to the results of BSA sequencing and KASP genotyping,the candidate gene region of resistance was determined,besides the gene sequence and relative expression was analyzed,and the key genes controlling the resistance of‘Honggengansutao 1’to M.incognita were discovered step by step.Through above experiments,this study initially identified the possible key genes to control the resistance of‘Honggengansutao 1’to M.incognita.The main results are as follows:1.We used the strategy of BSA constructed resistance pool in BC₁ generation,a total of 2,442,036SNP_S traits were detected.Based on the results of genotyping,the homozygous and heterozygous SNP loci in F₁ and the homozygous parents of‘Honggengansutao 1’and‘Bailey’were screened,total of1,569,564 polymorphic markers were selected.The parent‘Honggengansutao 1’was selected as the reference parent to analyze and calculate the SNP-indexs of 1,569,564 marker loci between the two progenies.At the 95%confidence level,two progenies were selected for the SNP site with significant difference in SNP-index in the whole genome.77 polymorphic marker loci were obtained.2.A total of 3883 loci（85.7 of the total number of loci）were genotyped with 15 SNPs for F₂generation.The results of independence test showed that SNP3（CHR2:4905737）,SNP5（CHR2:5397749）,SNP7（CHR2:5582276）were significantly related to the resistance to M.incognita of‘Honggengansutao 1’.3.Twenty-five R genes in the candidate region were analyzed by using‘Honggengansutao 1’and‘Bailey’at different infection stages.The expression of key candidate genes were analyzed,and the results showed that expression of the key candidate gene ppa020745m in‘Honggengansutao 1’was increased with the infection of nematode,the expression level increased significantly at 12 h after infection,and was not expressed in‘Bailey’.The upstream promoter sequence was found a 35bp deletion in the resistant germplasm.In 250 F₂ progenies,the results showed that the fragment was absent in 86 resistant progenies,and the deletion was a double peak in 115 resistant progenies,which suggested that the deletion fragment was absent or heterozygous in disease-resistant materials.The fragment was present in 49 susceptible progenies.