| Title: | Identification of AFLP markers in soybean linked to resistance to Meloidogyne javanica and conversion to sequence characterized amplified regions (SCARs) |
| Authors: | Mienie, C.M.S., Fourie, H., Smit, M.A., Van Staden, J., Botha, F.C. |
| Source: | Plant Growth Reg. 2002, 37(2):157-166 |
| Abstract: | Meloidogyne javanica is the most widely spread nematode pest on soybean in South Africa. Only a few registered commercial South African cultivars are poor hosts of this nematode species and there is an urgent need for an efficient breeding programme for resistant cultivars of all maturity groups. However, breeding is hampered by laborious screening procedures for selection of poor host cultivars and/or lines. The objective of this study was to develop an economically viable molecular marker system for application in selection procedures. Both Restriction Fragment Length Polymorphism (RFLP) and Amplified Fragment Length Polymorphism (AFLP) screening techniques identified markers linked to gall-index variation in a segregating population of 60 F-2 progeny from a cross between a resistant cultivar (Gazelle) and a highly susceptible variety (Prima). A codominant RFLP marker( B212) was linked significantly to M. javanica resistance and explained 62% of the variation in gall-index. Seven AFLP markers were linked significantly to the resistance trait, of which four were linked in repulsion phase and three in coupling phase. All seven AFLP markers mapped to LG-F (Linkage Group F) on the public soybean molecular map. The major quantitative trait locus (QTL) for resistance mapped between markers E-ACC/ M-CTC2(SOJA6) (linked in coupling phase), B212 and E-AAC/M-CAT1(SOJA7) (linked in repulsion phase). These two AFLP markers bracketing the major resistance QTL were successfully converted to SCARs (Sequence Characterized Amplified Regions). Marker E-ACC/ M-CTC2 was converted to a codominant SCAR marker SOJA6, which accounted for 41% of variation in gall-index in the mapping population. Marker E-AAC/M-CAT1 was converted to a dominant SCAR marker (SOJA7) and explained 42% of gall-index variation in the mapping population. These two markers mapped approximately 3.8 cM and 2.4 cM respectively from the resistance QTL. This study represents the first report of the development of PCR-based sequence specific markers linked to M. javanica resistance in soybean. |