Investigating For Haplotype Diversities Of Powdery Mildew Resistance Loci In Guizhou And Sichuan Wheat Cultivaries

A collection of76wheat varieties mainly from Guizhou and Sichuan was used in this study.To evaluate their resistance to powdery mildew in field, these cultivars were planted in Guiyang，Hezhang and Mianyang in2012and2013,respectively.18molecular markers linked to resistancegenes were selected to identify which resistance genes each cultivar carried, to explore theircontributions for resistance to wheat powdery mildew and investigate haplotype diversity ofpowdery mildew resistance loci in wheat cultivars from Guizhou and Sichuan. A high-throughputgenotyping technology-DArTseq was used to scan wheat whole genomes, to investigate thegenetic diversity of wheat cultivars in Guizhou and Sichuan Provinces. The results are as follows:1.18(23.28%) wheat cultivars evaluated had resistance to powdery mildew in Guiyang,13(30.19%) in Hezhang and13(27.40%) in Mianyang. All of these resistant cultivars wereinmune to powdery mildew.2.44.00%of Guizhou wheat cultivars showed resistance to powdery mildew, includingGuinong18, Guinong19, Guinong25, Guinong26, Guinong28, Fengyou10and Aimai7.19.44%ofSichuan wheat cultivars showed resistance, including Mianmai185, Mianmai228, Mianmai367andXikemai3. However, wheat cultivars from other areas were all susceptible to powdery mildew. Thissuggested that wheat powdery mildew was more serious in Guizhou and Sichuan than the otherregions, and the races of powdery mildew were more toxic here。3. According to scanning of resistant genes, the most cultivars (82.00%) carried Pm30. Morethan half of cultivars carried Pm24, Pm31and Pm41, accounting for56.00%,58.00%and73.00%, respectively. There were only2cultivars carrying Pm1. The frequencies of Pm30were76.00%,86.11%and81.25%of cultivars in Guizhou, Sichuan and other areas, respectively.4. Correlation coefficients were calculated among the cultivars resistance and Pm genes theircarrying. The Pm4, Pm21and Pm35were significantly associated with the resistance to powderymildew with r-value of0.36,0.27and0.21, respectively. It suggested that three genes played asignificant role in resistant to wheat powdery mildew in southwest China, and could be pyramidedin wheat resistant breeding by MAS.5. Haplotyping analysis revealed that our collection formed72haplotypes, including2-10gene loci. The haplotypes with6genes were the most frequency in all the cultivars. The haplotypeof was Pm4+Pm21+Pm24+Pm30+Pm31+Pm41+Pm42occurred in the resistant cultivars fromGuizhou, and Pm21+Pm24+Pm30+Pm31+Pm41in that from Sichuan. While the haplotype of Pm24+Pm30+Pm31+Pm35+Pm41+Pm42was occurred in the cultivars sensitive to powderymildew. The sensitive cultivars were mainly absent from Pm4、Pm21or Pm35compared to thehighly resistant ones.6. In order to investigate genetic diversity, DArTseq technology was used to genotype thewhole genome. Finally,13838SNP markers were polymorphic and scored with high confidenceamong our collection. The Nei-Li genetic distance coefficients ranged from0.52to0.98, withoverall mean of0.62. The greatest distance was observed between Mianmai40and Mianmai47, andthe minimum was between Guimai12and Fengyou9. Aconsensus dendrogram obtained fromUPGMA was constructed, our collection formed five groups, according to its origins.