Fine Mapping The Resistance Gene Ve And Development Of Linkage Markers To Potato Verticillium Wilt

Potato（Solanum tuberosum L.）is the one of the most important non-cereal food crops in the world which plays an important role in food security.Disease is one of the main threats to potato production.Potato Verticillium wilt,a fungal disease,cause a loss of potato yield by 5 to 12 tons per hectare in producing areas.Cultivating disease-resistant potato varieties is still the most economical and effective way to prevent and control diseases.Mapping disease resistance genes and developing linkage markers could accelerate the breeding processes of potato disease resistance varieties.However,little is known about potato Verticillium wilt resistance genes and associated molecular markers.In this study,we have constructed a backcross BC₁resistant/susceptible segregation population by hybridization of diploid potato interspecific hybrids C545 and V67 the results obtained are as follows:1. Phenotypic identification of the BC₁population.175 individual phenotypes which segregation ratio of resistance to susceptible was in line with 1:1.2. Mapping of Ve gene:23 Verticillium wilt disease resistant and 22 susceptible （SNP-index）distribution map was plotted.It shows that Verticillium wilt disease resistant genes are located on chromosome 5,ranging from 0 to 4.5 Mb which is consistent with our previous study.We have developed polymorphism markers in this location,including a CAPS marker,4 amplification markers and 10 SSR markers.Together with the 12 polymorphic markers screened previously,we have retested the individual plant of the population.A genetic linkage map with a total length of 24.4c M was drawn by using the 27 polymorphic markers,which average spacing was 0.90 c M.If the marker location of a genetic linkage map has a good linear relationship with its corresponding chromosome position,it indicates that the mapping results are reliable.The farthest linkage marker of Verticillium wilt disease resistant is C3.gene Ve ranging from 3.95 Mb to 5.71 Mb,which is located between linkage markers C2 and SSR514.We further used the two markers（C2 and SSR514）to rescreen the individual plant.Seven recombination individuals were selected from 80 plants.Three co-segregated markers have detected that the exchange of recombinant CV-287 occurs between maker SSR403 and SSR207 which can further narrow down the mapping interval.The phenotypes of the recombinant individuals and the amplification results of other co-segregated markers remain to be completed.3. Analysis of NBS-LRR disease resistance genes by q RT-PCR.There are 22NBS-LRR disease resistance genes in the interval.We performed the Verticillium wilt infection assays.The samples were collected at 0 h,4 h,18 h,3 d,and 7 d for gene expression assays.The q RT-PCR showed that 5candidate genes were significantly up regulated at one time point in the resistant parents compared with the susceptible parents,which are probably related to Verticillium wilt disease resistance.However,their gene expression levels remain need to be further verified in the disease-resistant and disease-susceptible offspring.Taken together,our work has further laid the foundation for developing molecular markers for fine mapping and cloning potato Verticillium will disease resistance gene Ve.