Development Of Potato Germplasm With Stacked Late Blight Resistance Genes Pta1 And R8 Assisted By Molecolar Maker Selection

As the fourth largest food crop in the world,potato plays an important role in global food security.Late blight is the most serious potato disease which seriously restricting the development of the potato industry.Breeding varieties with high resistance to late blight is considered to be the most cost-effective strategy to control late blight.Stacking multiple late blight resistance genes is an effective strategy to cope with late blight.Molecular marker-assisted selection(MAS)for tracking and identification of resistance genes can quickly and effectively stack late blight resistance genes,which could greatly reduce the efforts on late resistance breeding,and is an effective way for rapid selection of excellent late blight resistance germplasm accessions.The accession used in this study was F1,produced by crossing of S.papita×Brugus,containing the resistance gene Pta1 and the cultivars containing R8.The hybrid progenies were rapidly selected by specific molecular markers of late blight resistance genes R8 and Pta1.The AVR-R protein recognition strategy and detached leaf assay(DLA)were used to verify the resistance genes in the obtained accessions.Finally,many germplasm resources with desirable agronomic characters and high resistancet were obtained according to agronomic characters.The results are as follows:1.A total of 278 progeny of 7 combinations were selected using specific molecular markers of Pta1 and R8.A total of 126 accessions with positive molecular marker were identified,including 35 accessions containing Pta1 alone,67 accessions containing R8 alone,and 24 pyramid accessions containing both Pta1 and R8.2.Six of the 24 Pta1 and R8 pyramid accessions were randomly selected to verificat presence of Pta1 and R8 using AVR-R protein recognition strategy by agro-infiltration transient expression.The results showed that the tagert resistant genes were successfully stack.3.Resistance was evaluated by agressive P.infestans isolats(HB0914-2,UK3928 A,11604,061B).Finally,50 accessions with high resistance to late blight were identified,including 24 pyramid samples and 26 samples containing Pta1 alone.4.The agronomic characters of resistant accessions were investigated and analyzed(Including plant phenotype of above ground part and stolon phenotype and tuber yield under ground part).Finally,12 accessions with good agronomic characteristics were selected from these accessions(12-3,12-13,17-4,17-7,17-16,17-22,17-42,17-59,17-61,17-79,17-91,17-96).In this study,molecular markers were used to quickly and efficiently select late blight resistant accessions from the progeny and identified the Pta1 and R8 stacked accessions.Using AVR-R protein recognition method,detached leaf assay and agronomic traits investigation,the desirable accessions with pyramided Pta1 and R8 and good agronomic characteristics were selected from a large number of hybrid progeny.Those excellent accessions will provide germplasm resources for late blight resistance breeding and intermediate accessions to the stack more late blight resistance genes.