Location: Crop Genetics and Breeding ResearchTitle: Major QTLs for resistance to early and late leaf spot diseases are identified on chromosomes 3 and 5 in peanut (Arachis hypogaea)
|CHU, Y - University Of Georgia|
|CHEE, P - University Of Georgia|
|CULBREATH, A - University Of Georgia|
|ISLEIB, T - North Carolina State University|
|Holbrook, Carl - Corley|
|OZIAS-AKINS, P - University Of Georgia|
Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2019
Publication Date: 7/5/2019
Citation: Chu, Y., Chee, P., Culbreath, A.K., Isleib, T.B., Holbrook Jr, C.C., Ozias-Akins, P. 2019. Major QTLs for resistance to early and late leaf spot diseases are identified on chromosomes 3 and 5 in peanut (Arachis hypogaea). Frontiers in Plant Science. 10:1-13.
Interpretive Summary: Early and late leaf spot are the major foliar diseases of peanut and costs the U.S. peanut industry over $ 50 million annually. The development of resistant varieties is a sustainable solution to reduce these costs. Genetic markers linked to resistant genes can be used in marker assisted selection (MAS) to speed the development of resistant varieties. The objective of this study was to genotype and phenotype a segregating population of peanut to attempt to identify genetic markers liked to resistant genes. Three genetic markers were identified for resistance to late leaf spot, and three different genetic markers were identified for resistance to early leaf spot. These markers can be used to develop varieties with resistance to leaf spot disease.
Technical Abstract: Early and late leaf spots (LLSs) are the major foliar diseases of peanut responsible for severely decreased yield in the absence of intensive fungicide spray programs. Pyramiding host resistance to leaf spots in elite cultivars is a sustainable solution to mitigate the diseases. In order to determine the genetic control of leaf spot disease resistance in peanut, a recombinant inbred line populations (Florida-07 x GP-NC WS 16) segregating for resistance to both diseases was used to construct a SNP-based linkage map consisting of 855 loci. QTL mapping revealed three resistance QTLs for LLS qLLSA05 (phenotypic variation expained, PVE = 7-10%), qLLSB03 (PVE = 5-7%), and qLLSB05 (PVE = 15-41%) that were consistently expressed over multi-year analsysis. Two QTL, qLLSA05 and qLLSB05, confirmed our previously published ATL-seq results. For early leaf spot, three resistance QTLs were identified in multiple years, two on chromosome A03 (PVE = 8-12%) and one on chromosome B03 (PVE = 13-20%), with the locus qELSA03_1.1 coinciding with the previously published genomic region for LLS resistance in GPBD4. Comparitive analysis of the genomic regions spanning the QTLs suggests that resistance to early and LLS are largely genetically independent. I addition, QTL analysis on yield showed that the presence of resistance allele in qLLSB03 and qLLSB05 loci might result in protection from yield loss caused by LLS disease damage. Finally, post hoc analysis of the RIL subpopulation that was not utilized in the QTL mapping revealed that the flanking markers for the QTLs can successfully select for resistance and susceptible lines, confirming the effectiveness of pyramiding these resistance loci to improve host-plant resistance in peanut breeding programs using marker-assisted selection.