Association mapping of quantitative resistance to charcoal root rot in mulberry germplasm

• Published in: PloS one Vol. 13; no. 7; p. e0200099
• Main Authors: Pinto, Marian Vincent, H S, Poornima, M S, Rukmangada, R, Triveni, Naik, V Girish
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 06-07-2018; Public Library of Science (PLoS)
• Subjects: Admixtures; Amplified fragment length polymorphism; Biology and Life Sciences; Cardiovascular disease; Charcoal rot; Crop diseases; Cultivars; Gene mapping; Genetic analysis; Genetic improvement; Genomes; Genotype & phenotype; Genotypes; Germplasm; Inoculation; Linkage analysis; Macrophomina phaseolina; Mapping; Markers; Medicine and Health Sciences; Microbial drug resistance; Molecular biology; Molecular chains; Mulberry; Outbreaks; Pathogens; Phenotypes; Physiological aspects; Research and Analysis Methods; Root rot; Root rots; Sericulture; Sorghum; Subpopulations; Survival; Sustainability; Transcription factors; India
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0200099

Outbreaks of root rot disease in the productive South Indian sericulture belt have threatened the sustainability of the industry. Macrophomina phaseolina (Tassi) Goid. causing charcoal rot is the predominant pathogen to which all productive mulberry cultivars are susceptible. The present study was undertaken to identify molecular markers associated with charcoal rot resistance in mulberry. A mapping panel comprising 214 diverse entries from the Indian germplasm collection was assessed for charcoal rot resistance by artificial inoculation. Resistance to the pathogen was observed in 20 entries, and 51 were found to be moderately resistant. A total of 773 alleles generated across 105 SSR loci and 20,384 AFLP markers generated using 32 EcoRI-NN and MseI-CNN primer combinations were used in genetic analysis. The panel was weakly structured with two subpopulations. However, most entries were found to be admixtures. Survival of cuttings and number of roots per sapling were associated with root rot resistance. Association mapping was performed using different linear mixed models. Five AFLP markers explaining 9.6-12.7% of the total phenotypic variance were found to be significantly (p < 0.05) associated with root rot resistance. Significant associations were also detected in four AFLP markers for survival of cuttings, and these markers explained 10.7-14.2% of the total phenotypic variance. These markers should be validated using mapping populations derived from contrasting biparental combinations by linkage analysis for use in marker-assisted gene pyramiding for durable resistance. The resistant genotypes identified in this study will substantially contribute to genetic improvement of mulberry for charcoal rot resistance and can be integrated into conventional breeding programmes.