Genetic Analysis And Preliminary Gene Mapping Of Heat-tolerant Resistance To Bacterial Wilt In Tomato

Tomato bacterial wilt is a soil-borne disease caused by Ralstonia solanacearum which has become a limit of tomato production.It has been found that the resistance of some materials always decrease at high temperatures（above 30°C）,which is strongly harmful to production.One special material’1271’with heat-tolerant resistance（33°C）has been identified in our lab.This study carried out the genetic analysis and preliminary mapping of this resistance gene.The main results are as follows.1.Under the temperatures of 28°C and 33°C,’1271’and classic resistance source’Hawaii7996’were artificially inoculated with a strong aggressive strain of Ralstonia solanacearum and were observed for 15 d.The resistance of’1271’was stronger than that of’Hawaii7996’under both temperatures.When the temperature increased to 33℃,the resistance of two materials decreased,but the’1271’decreased slowly.The disease index of’1271’and’Hawaii7996’at 15 dpi were 69.17%and 99.17%,respectively,indicating that the resistance of’1271’was relatively tolerant to high temperature.2.The inheritance of resistance was analyzed by using the mixed‘major gene+polygene’model with four generations including’1271’（P₁）,’Hawaii7996’（P₂）and their derived F₁,F₂.The results implied that high temperature-tolerant resistance was controlled by two pairs of additive-dominant major genes and additive-dominant polygenes.The estimated inheritability of major genes was 41.99%.3.79 polymorphic markers were screened out from 411 pairs of InDel markers using DNA of parents and F₁,and the genetic linkage map was constructed using JoinMap3.0software using the genotype data obtained from the F₂ population.The map is consisted of a total of 12 linkage groups and contained 65 InDel markers,covering a total length of263.31 cM.The heat-tolerant resistance gene to bacterial wilt was preliminarily located at the lower end of chromosome 10,under marker W470.