09N3-30, a new peach germplasm with green peach aphid resistance

Abstract:【Objective】Peach [Prunus persica (L.) Batsch] is an economically important fruit tree origi-nated from China and cultivated across the world. The green peach aphid (GPA, Myzus persicae Sülzer) is the major pest in peach orchards. Three times of chemical controls are usually required to control GPA epidemics effectively in the spring, resulting in the increases of the cost and the risk of food safety and ecological hazards. Using host-plant resistance to control the aphid infestation is a sustainable, eco- friendly method of pest management. New host-plant germplasms with resistance to the pest can speed up the breeding of new varieties with the resistance. To date, several wild aphid-resistant peach germplasms have been identified, such as Fen shouxing, Rubira, Weeping Flower Peach and Prunus davidi- ana, by Avignon Centre of French Academy of Agricultural Sciences and Zhengzhou Peach Germplasm Repository. However no cultivated peaches with the resistance to GPA has been found yet.【Methods】In this study, a new Myzus persicae resistant peach germplasm 09N3-30 derived from cultivated variety were created and evaluated for resistance to green peach aphids. The inheritance was analyzed and the gene was mapped by Bulked Segregant Analysis (BSA).【Results】Here, we introduced a new GPA-re- sistant germplasm characterized by Myzus persicae resistance, 09N3-30, that exhibited strong antixeno- sis-type resistance. However, different from previous report (Rm1, Rm2, and Rm3), allergic spots did not occur in the new materials after aphid infestation. We did not observe any leaf curling on GPA-resis-tant 09N3-30 individual or any aphid colonization in the young shoot tips in the experimental field with-out any chemical insecticide control against GPA. However, the opposite observation was observed on susceptible individuals, and there were large quantities of GPA colonization at leaf curling sites. After aphid inoculation, the number of aphids in resistant Rm3 and 09N3-30 peach trees decreased to approxi-mately half number on the second day after inoculation, and near 100% of the aphids had left within 6 days. We constructed two F1 segregating populations to analyze the inheritance of the new trait. The largest population was produced from the combination of Zhongtaohongyue × 09N3-30, with a total of 287 individuals. The segregation of phenotypes was approximately 1∶1 for resistant : susceptible (χ2 =0 to 2.36). This segregation ratio is indicative of a trait controlled by a single dominant gene or major ef-fect gene. To identify the causative gene for the new resistance phenotype, high- throughput specific length amplified fragment sequencing of the 2 parental lines and resistant/susceptible pools generated approximately 22.0 million high-quality short reads. The SNP-index was calculated by integrating the polymorphism of the two pools. The overlap revealed a single peak in the genomic region between Pp03:21 523 514 and Pp03:26 958 658; the GPA resistant gene was located in the 5.44 Mb region on chromosome 3.【Conclusion】The resistance phenotype, genetic pedigree and mapping analysis have confirmed 09N3-30 is a new germplasm resource resistant to Myzus persicae.