QTL localization analysis and SSR molecular marker develop⁃ ment of pepper resistance to anthracnose by SLAF-Seq technology

【Objective】 The QTL localization analysis for resistance to anthracnose of pepper was analyzed by SLAFSeq technology，and the molecular markers closely linked with the QTL for resistance to anthracnose were developed to provide theoretical reference for molecular marker assisted selection breeding for resistance to anthracnose of pepper.【Method】The F₂ generation population was constructed with the resistant material PPTC26-3-1-1-1-1-1 and susceptible material 1287 as the parents，and the molecular marker was developed by SLAF-Seq technology，and the high-density ge‐ netic linkage map was constructed，combined with the phenotypic data. QTL analysis was performed for anthracnose re‐ sistance of pepper fruit during the color transition stage by composite interval mapping（CIM），and SSR loci were identi‐ fied by Microsatellite（MISA）. 【Result】 A total of 423351627 reads were obtained from parent and offspring samples，of which 8130516 reads were from PPTC26-3-1-1-1-1-1 and 6621396 reads were from 1287. The average number of reads from 120 offspring samples of F₂ generation was 34049987. A high-density genetic map of pepper was constructed，which contained 4671 SNP molecular markers distributed in 12 linked groups with a total map distance of 1567.53 cM and an average map distance of 0.34 cM. One QTL（CaR10.1）related to anthracnose resistance was detected. It was located in the physical range of 187930592-189766111 bp on chain group number 10. A total of 23 genes were located in the asso‐ ciated region. According to the gene function annotation，1 gene encoded the isoform X2 of the presumed late blight resis‐ tance protein homolog R1B-23，and 1 gene encoded PPR protein，which might be related to the resistance to anthracnose during the color transition stage of pepper fruit. SSR marker T482 was developed within the associated QTL interval，and verification in F₂ population showed that the bands amplified by T482 primer in F₂ population individual were consistent with phenotypic identification. In the F₂ generation，53 strains had bands of resistant parents and 25 strains had bands of both resistant and susceptible parents. In F₂ generation infected individuals，42 strains contained bands of infected parents. 【Conclusion】 A high-density genetic linkage map is constructed. The resistance to anthracnose during the color transition stage of pepper fruits is localized on chain group number 10，and an SSR molecular marker T482 is developed in the asso‐ ciated interval. The results can be used to identify the resistance to anthracnose of pepper fruit during color transition stage，and can be combined with needle inoculation method to improve the identification accuracy.