The Genetic Analysis And Localization Of Bacterial Fruit Blotch Resistance Gene In Xinjiang Melon

It is a safe and effective method to control Bacterial Fruit Blotchs（BFB）by using the own resistance gene of melon.In order to discover resistance gene to BFB and find SSR molecular markers closely linked to the resistance gene,we have used three methods as follows.The isolated and purified pathogens of BFB were identified by morphological structures and analyzing 16S rDNA sequence.The inheritance of BFB resistance gene was studed by jointly analyzing the segregation of risistance to BFB in the BC₁ and F₂ derived from two crosses between the same resistance melon Shenshuai and two different susceptible melons,respectively.SSR（Simple Sequence Repeat）molecular marker technology and BSA（Bulked Segregation Analysis）were used to localization of the BFB resistance genes in Shenshuai used F₂ derived from a cross between the resistance melon Shenshuai and susceptible melon Pishankuiruike.（1）The morphology of isolated and purified pathogens of BFB in this experiment were milkiness,roundness and 1-2 mm in diameter and their characters were similar to the control strains and previous reports.Their 16S rDNA sequences shared more than 99%similarity to the published 16S rDNA sequence of Acidovorax citrulli.（2）The segregation of resistance to BFB in the BC₁ and F₂ derived from the Shenshuai×Pishankuiruike and Shenshuai×JS,respectively,illustrated that the inheritance of resistance gene in Shenshuai was inheritance of quantitative traits.（3）Among 396 SSR markers distributed on 12 linkage groups,24 polymorphic markers were identified for constructing genetic linkage map and QTL analysis in the 98 F₂ population of 2016 derived from a cross between Shenshuai and Pishankuiruike.The resistance gene was mapped in LGIV between the ECM231 and ECM184 marker and the genetic distance is 30.69cM.（4）Among 396 SSR markers distributed on 12 linkage groups,62 polymorphic markers were identified for constructing genetic linkage map and QTL analysis in the 188 F₂population of 2017 derived from Shenshuai×Pishankuiruike.Two resistance genes were located on LGVII between the CM79 and CMAGN75 marker,CMAGN75 and ECM182marker,respectively.The third one was mapped in LGIX between the ECM150 and CMCTN7marker.The genetic distance are 35.3cM,20.32cM,37.51cM,respectively.