Genetic mapping of soybean cyst nematode race-3 resistance loci in the soybean PI 437.654

Abstract

Resistance to the soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) is difficult to evaluate in soybean [Glycine max (L.) Merr.] breeding. PI 437.654 has resistance to more SCN race isolates than any other known soybean. We screened 298 F6∶7 recombinant-inbred lines from a cross between PI 437.654 and 'BSR101' for SCN race-3 resistance, genetically mapped 355 RFLP markers and the I locus, and tested these markers for association with resistance loci. The Rhg 4 resistance locus was within 1 cM of the I locus on linkage group A. Two additional QTLs associated with SCN resistance were located within 3cM of markers on groups G and M. These two loci were not independent because 91 of 96 lines that had a resistant-parent marker type on group G also had a resistant-parent marker type on group M. Rhg 4 and the QTL on G showed a significant interaction by together providing complete resistance to SCN race-3. Individually, the QTL on G had greater effect on resistance than did Rhg 4, but neither locus alone provided a degree of resistance much different from the susceptible parent. The nearest markers to the mapped QTLs on groups A and G had allele frequencies from the resistant parent indicating 52 resistant lines in this population, a number not significantly different from the 55 resistant lines found. Therefore, no QTLs from PI 437.654 other than those mapped here are expected to be required for resistance to SCN race-3. All 50 lines that had the PI 437.654 marker type at the nearest marker to each of the QTLs on groups A and G were resistant to SCN race-3. We believe markers near to these QTLs can be used effectively to select for SCN race-3 resistance, thereby improving the ability to breed SCN-resistant soybean varieties.

Inheritance pattern and selection criteria for resistance to soybean cyst nematode races 3 and 9

“…Differentials and susceptible control were used as monitor the SCN populations and their responses remained consistent while no race shifts occurred. The FI values distribution for each SCN race (Figure 1 A and B) shows that the resistance to SCN in soybean is a quantitative trait, as reported by other researchers (Mansur et al, 1993;Concibido et al, 1994;Webb et al, 1995;Yue et al, 2001). Table 1.…”

“…Soybean cyst nematode (Heterodera glycines Ichinohe -SCN) is a pathogen that affects soybean production worldwide with losses that reached 9 million tons in 1998 (Wrather et al, 2001). Sources of resistance to SCN were reported first by Ross (Ross & Brim, 1957).…”

Qualidade fisiológica e composição química das sementes de soja com variação na cor do tegumento

“…De acordo com Webb et al (1995), esta região apresenta-se associada com caracteres relacionados à tolerância a nematóides formadores de galhas, e para Mansur et al (1998), a região também esta associada a stresse causado na planta por fatores ambientais, entre eles à tolerância a seca.…”

Marker-assisted selection strategies for developing resistant soybean plants to cyst nematode

“…According to Falconer and Mackay (1996), heritability estimates depend on the plant material, the estimation method and the experiment. Webb et al (1995) reported a broad-sense heritability of 97% for resistance to race 3 in crosses with PI 437654.…”

“…One of the QTL with major effect in LG G, designated rhg1, confers resistance to several races (Chang et al 1997, Concibido et al 1997, Meksem et al 2001, Yue et al 2001, Glover et al 2004, Silva et al 2007b, while another in LG A2 (Rhg4), with major effect, confers specific resistance to race 3 (Mahalingam and Skorupska 1995, Webb et al 1995, Chang et al 1997, Meksem et al 2001). …”