Identificação de QTL associados à simbiose entre bradyrhizobium japonicum/B. elkanii e a soja [Glycine max(L.) Merr.]

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Nitrogen (N) demand of soybean [Glycine max (L.) Merrill] can be supplied via biological nitrogen fixation (BNF) through the inoculation with selected Bradyrhizobium japonicum/B. elkanii strains, such that today no N-fertilizer is recommended for the crop in Brazil. However, traits related to BNF have not been lately evaluated in soybean breeding programs, with priority given to yield and resistance to diseases. The objective of this study was the identification of QTL (Quantitative Trait Loci) related to BNF using microsatellites (SSR) markers, in an F2:7 population of 157 Recombinant Imbred Lines (RILs), derived from the cross between parental cultivars with contrasting capacities of BNF, Bossier (high) and Embrapa 20 (medium). Soybean lines were grown under greenhouse conditions for the evaluation of the parameters of plant growth (shoot dry weight, SDW), and nodulation (nodule number, NN; nodule dry weight, NDW and the relation nodule dry weight/nodule number, NDW/NN). All parameters evaluated showed statistical differences (P= 0.05), indicating genetic variability among soybean lines. Sixteen markers located in six out of the twenty soybean linkage groups have been mapped, covering about 5% of the genome (151.6 cM). The regression analysis identified twelve significant associations in four linkage groups (B1, C2, D1b and H): three for shoot weight, four for nodule number, four for nodule weight and three for the medium value of nodule weight. All QTL had minor effects (R2 = 2,5 to 8,0%) similar to previous reports in an F2:3 of BRS 133 (low) x Embrapa 20 (medium) (Nicolás et al., 2005). However, seven QTL were confirmed in both populations, indicating that they might be effective in increasing BNF in soybean breeding programs.

ASSUNTO(S)

microbiologia soybean symbiosis microbiology soja - melhoramento genético simbiose

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