Mapping Of QTLs identified in a novel source of resistance to the Root-Knot nematode (Meloidogyne incognita race 3) in cotton (Gossypium barbadense L.)

The root-knot nematode (RKN) Meloidogyne incognita is a serious pest of cotton, causing direct damages and increasing the severity of other root diseases. Host plant resistance and the development of resistant varieties have the potential to efficiently contribute to RKN management in cotton. High levels of resistance has been identified in a breeding line (Auburn 623 RNR) derived from a cross between two moderately-resistant accessions, and this source of resistance has recently been used to develop highly-resistant adapted lines. Nevertheless, continuous exposition to the same source of resistance may lead to the selection of virulent RKN isolates, and the identification of new sources of resistance is important for a durable resistance. We have previously demonstrated that G. barbadense accession CIR1348 (Mota et al. 2013; Da Silva et al. 2014) shows the same high level of resistance as the Auburn 623 RNR source, and in this work we describe the mapping of QTLs associated to RKN resistance in this novel source of resistance. An interspecific F2 population of 174 plants, constructed from a cross between the resistant accession CIR1348 and the susceptible Upland cotton variety FiberMax 966, was genotyped using SSR markers and plant reaction to inoculation with M. incognita race 3 was evaluated under controlled conditions. RKN resistance was scored using the following criteria: galling index (GI), egg mass index (EMI), number of eggs per gram roots (E/GR) and reproduction factor (RF). A genetic map was constructed using a set of 271 microsatellite markers, and a total of 262 loci assembled into 29 linkage groups at LOD ≥4. The total length map was 4,294 cM with an average distance of 15.1 cM between adjacent loci. QTL mapping identified four chromosomal regions harboring significant QTLs for one or more of the scored traits. Two QTLs (for GI on c2 and for EMI, E/GR and RF on c9) had a positive contribution from the susceptible parent FM966. A major QTL, with a positive contribution of the resistant parent CIR1348 was identified on c11, in the interval flanked by SSR markers CIR316 and CIR069. This major QTL mainly influences nematode egg production, and acted in conjunction with minor QTLs to confer the high level of resistance in cotton accession CIR1348. This same interval has been identified as harboring a major RKN resistance locus in other sources of resistance, including in M-315 RNR (Gutiérrez et al. 2010; Jenkins et al. 2012), and this region of c11 has been shown to be rich in disease resistance genes (Wang et al. 2015). Similarly to other sources, the resistance in accession CIR1348 fits a two-genes model, but in contrast to the M-315 RNR line, resistance in CIR1348 is partially recessive. CIR1348 constitutes a new source of RKN resistance loci, and the identification of markers associated to major QTLs will facilitate the introgression of resistance into desirable genetic backgrounds. (Texte intégral)

Bibliographic Details

Main Authors:	Gomez, G.M., Moretzon, M.C., da Silva, Esdras Henrique, Furlanetto, Cleber, Silvba, J.G.P., Lacape, Jean-Marc, Barroso, Paulo Augusto Vianna, Carneiro, Regina Maria Dechechi Gomes, Giband, Marc
Format:	conference_item biblioteca
Language:	eng
Published:	ICGI
Subjects:	F30 - Génétique et amélioration des plantes, H10 - Ravageurs des plantes,
Online Access:	http://agritrop.cirad.fr/582975/ http://agritrop.cirad.fr/582975/7/Gomez%20et%20al%202016%20WCRC6.pdf
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