Identification and validation of genetic markers associated with Meloidogyne incognita race 2 resistance in soybean, Glycine max (L.) Merr
2008
Fourie, Hendrika | Mienie, Charlotte M.S. | Mc Donald, Alex H. | De Waele, D. (Dirk)
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.
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