|PANDEY, MANISH - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India|
|WANG, HUI - University Of Georgia|
|KHERA, PAWAN - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India|
|VISHWAKARMA, MANISH - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India|
|KALE, SANDIP - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India|
|CULBREATH, ALBERT - University Of Georgia|
|Holbrook, Carl - Corley|
|VARSHNEY, RAJEEV - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India|
Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2017
Publication Date: 1/31/2017
Citation: Pandey, M.K., Wang, H., Khera, P., Vishwakarma, M.K., Kale, S.M., Culbreath, A.K., Holbrook Jr, C.C., Varshney, R.K., Guo, B. 2017. Genetic dissection of novel QTLs for resistance to leaf spots and Tomato spotted wilt virus in peanut (Arachis hypogaea L.). Frontiers in Plant Science. 8:25. doi: 10.3389/fpls.2017.00025.
Interpretive Summary: Peanut, also called groundnut, is the second most important legume oilseeds in the world. Genetic improvement of yield and production is always the ultimate goal. Peanut is susceptible to many diseases and the cost of disease control can be high. Since molecular breeding has advantages over conventional breeding approach, it is advisable to identify linked markers and then use these markers in improving the target traits through molecular marker-assisted selection. Therefore, we have used a RIL population called T-population for phenotyping and genotyping followed by construction of an improved genetic map and identification of QTLs associated with three important diseases. This study included four years of field evaluations of disease severity for early leaf spot, late leaf spot and TSWV from 2010 to 2013, and each year there were two planting dates (total eight field trials) in order to obtain better field rating (all naturally occurring). The genetic linkage map was improved to 418 marker loci. Major QTLs with larger contribution to the phenotypic variances were identified for all three diseases. Of the total 42 QTLs, 34 were mapped on the A sub-genome and eight mapped on the B sub-genome, suggesting that the A sub-genome chromosomes have more resistance genes than the B sub-genome. This genetic map was also compared with the diploid progenitor physical maps, and the co-linearity found was good. These QTLs will be further studied for fine mapping of linked markers and identification of potential candidate genes for validation in order to be used in marker-assisted breeding.
Technical Abstract: Peanut is an import crop, economically and nutritiously, but high production cost is a serious challenge to peanut farmers as exemplified by chemical spray to control foliar diseases such as leaf spots and thrips, the vectors of tomato spotted wilt virus (TSWV). The objective of this research was to map the quantitative trait loci (QTLs) for resistance to leaf spots and TSWV in one recombinant inbred line (RIL) mapping population of ‘Tifrunner × GT-C20’ for marker-assisted breeding. Here, we report the improved genetic linkage map with 418 marker loci with a marker density of 5.3 cM/loci, and QTLs associated with multi-year (2010-2013) field phenotypes of foliar disease traits, including early leaf spot (ELS), late leaf spot (LLS), and TSWV. A total of 42 QTLs were identified with phenotypic variance explained (PVE) from 6.36% to 15.6%. There were nine QTLs for resistance to ELS, 22 QTLs for LLS, and 11 QTLs for TSWV, including six, five, and one major QTLs with PVE higher than 10% for resistance to each disease, respectively. Of the total 42 QTLs, 34 were mapped on the A sub-genome and eight mapped on the B sub-genome. This suggests that the A sub-genome chromosomes have more resistance genes than the B sub-genome. This genetic linkage map was also compared with two diploid peanut physical maps, and the overall co-linearity was 48.4% with an average co-linearity of 51.7% for the A sub-genome and 46.4% for the B sub-genome. The identified QTLs associated markers and potential candidate genes will be studied further for possible application in molecular breeding in peanut genetic improvement for disease resistance.