1 1Laboratory of Tropical Crop Improvement, Department of Biosystems, Faculty of Bioscience Engineering, Catholic University of Leuven (K.U. Leuven), Kasteelpark Arenberg 13, 3001 Leuven, Belgium, School of Environmental Sciences and Development,
North-West University, Private Bag X6001, 2520 Potchefstroom, South Africa
2 2Agricultural Research Council-Grain Crops Institute, ARC-GCI, Private Bag X1251, 2520 Potchefstroom, South Africa;, Email: firstname.lastname@example.org
3 3Agricultural Research Council-Grain Crops Institute, ARC-GCI, Private Bag X1251, 2520 Potchefstroom, South Africa, School of Environmental Sciences and Development, North-West University, Private Bag X6001, 2520 Potchefstroom,
4 4Agricultural Research Council-Grain Crops Institute, ARC-GCI, Private Bag X1251, 2520 Potchefstroom, South Africa
Host-plant resistance to Meloidogyne incognita race 2 is a useful and cost-effective tool for optimising soybean yield as well as profitability. Locally no nematicide is currently registered on soybean and most crops used in soybean-based rotations are also susceptible to M. incognita race 2. The identification of molecular markers and subsequent application of marker-assisted selection (MAS) is a quick and effective way to expedite a nematode resistance breeding programme. The soybean cultivars LS5995 (resistant) and Prima2000 (susceptible) were therefore used as parents in crosses to obtain a segregating F2 mapping population for the identification of genetic markers linked to the resistance trait in LS5995. Inoculation with ca 10 000 M. incognita race 2 eggs and second-stage juveniles (J2) was performed 16 days after plant emergence. Subsequently, the F2 population was screened with a number of SSR evenly distributed throughout the genome. A major QTL was identified on linkage group (LG) M between the markers Satt201 and Satt590 accounting for 62.4% of gall index values, while a QTL explaining 80% of the variation in eggs and J2 per root system in the segregating F2 population is situated between Satt567 and Satt201. A minor QTL accounting for 37.1% of the variation in gall index values was identified between the markers Satt500 and Satt358 on LG-O and corresponds to a QTL for M. incognita race 3 resistance described in other publications. Presence of the abovementioned markers was confirmed in the progeny of a successive F6 population, as well as in a number of exotic and local soybean genotypes. Meloidogyne incognita race 2 MAS could, therefore, be used in a breeding programme using markers Satt201, Satt358, Satt487 and Satt590, which were identified and validated in this study.