Mapeamento e validação de QTLs de resistência ao nematóide de cisto da soja / Mapping and validation of QTLs for resistance to soybean cyst nematode

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

To study soybean (Glycine max (L.) Merrill) resistance to the cyst nematode - NCS (Heterodera glycines Ichinohe) and to help the implantation of the marker assisted selection in breeding programs, the present work was carried with the following objectives: (a) to study the inheritance of resistance to the races 3, 9 and 14 of NCS in different populations; (b) to identify and map microsatellites linked to gene(s) for resistance to those races in a population of recombinant inbred lines (RILs); (c) to validate QTLs in F2 populations originated from different resistance sources from which the QTLs were mapped; and (d) to map QTLs for several agronomic characteristics of soybean. In the inheritance study, four epistatic genes for resistance to the race 14 and three epistatic genes for the races 3 and 9 were detected in the RILs population of the crossing Hartwig x Y23. In F2 population from the crossing Msoy8001 x Conquista, a recessive gene conditioning moderate resistance and two recessive genes giving complete resistance to race 3 were identified. For race 14, two recessive genes for the moderate resistance were identified in the F2 population of the crossing S5995 x Renascença. In mapping of QTLs in RILs, for resistance to NCS, the following were identified: four QTLs for race 3 in the linkage groups (GL) G, A2, J and M, explaining from 12.9% to 34.8% of phenotypic variation; one QTL for resistance to race 9 in GL G, explaining 22% of resistance; and only significant associations between markers and race 14, mainly in the GL G and C2. For race 3, the assisted selection accomplished with the most significant markers of the GL G and A2 showed a result similar to that of the phenotypic selection. In validation of microsatellites for marker assisted selection of plants with resistance to race 3, the association of resistance with markers of GLs A2 and G was confirmed, and together the markers Satt309 in GL G and GMENOD2B in GL A2 showed 100% efficiency in selection (ES). For resistance to race 14, evaluated in the population S5995 x Renascença, only markers in GL G showed significant association with resistance. The Satt309 marker explained the highest proportion of phenotypic variance. The best marker combination for the selection of plants resistant to this race was Satt309 with Satt356, that together provided 100% of ES. In 2001, studying the QTLs mapping for agronomic characteristics, were mapped: five QTLs in GL D1a for the characteristics concerning to days for flowering - R1, plant height in flowering APF, first pod height APV, pod number per plant NVP, and seed number per plant NSP; four QTLs in GL N for the characteristics concerning to APF, R1, node numbers in maturation NNM, and days for maturation - R8; and two QTLs in GL F for node number at maturation NNM, and seed number per plant NSP. In evaluations performed in 2002, the QTLs were identified in GL A2 (NNM), C2 (APV, NVP), D1a (R1), N (R8), F (NNM), K (R8, APF and APV), H and J (both for NSP). For the yield, evaluated in 2001, QTLs were detected in the GLs E, G, O and K. In both years, consistent QTLs were mapped for R1 (GL D1a), R8 (GL N) and NNM (GL F). In 2001, the intervals between the markers Satt147 - Satt408 (GL D1a) and Sat_033 - Satt237 (GL N) were significant for several characteristics, therefore suggesting a pleiotropic effect of these regions for different characteristics. It is worth to emphasize that these results will be useful to the assisted selection for resistance to NCS in the Brazilian soybean breeding programs.

ASSUNTO(S)

marcadores moleculares glycine max glycine max soybean cyst nematode molecular markers genetica molecular e de microorganismos nematóide de cisto da soja qtls heterodera glycines heterodera glycines qtls

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