Avances en la identificación de QTL para dormición en sorgo granífero

RODRÍGUEZ M.VERÓNICA; GIECO JORGE OMAR; RÍOS, CRISTIAN D.; CERVIGNI, GERARDO C.L.; HEINZ, RUTH A.; CANTORO, RENATA; PANIEGO, NORMA; BENECH-ARNOLD R.L.

Pergamino

Simposio; III Simposio Nacional ? I Conferencia Internacional de SORGO; 2016

AIANBA y UNNOBA

Pre-harvest sprouting (PHS) can be a serious problem for sorghum production in the central region of Argentina, as grain maturation often takes place during rainy weather. As grain dormancy increases tolerance to PHS, this has been a desirable trait for breeders, but the quantitative nature of seed dormancy has made its manipulation difficult through classical breeding. The identification of molecular markers quantitatively associated with dormancy in sorghum will help to improve PHS tolerance in this crop. To approach this objective, two sorghum inbred lines with contrasting dormancy (IS9530 and RedlandB2) were used as parents to obtain segregating populations (F3 and F4) and RILs for QTL studies. In a recently published work (Cantoro et al., 2016) we reported results of QTL analysis performed on 190 families. A genetic map encompassing 96 SSR markers and a total length of 1331 cM was built. Seed dormancy was phenotyped using a germination index (GI) in F3 and F4 panicles under two contrasting environments (Castelar, Bs.As., and Manfredi, Córdoba). Six seed dormancy QTL for mature grains were identified (qGI-1, qGI-3, qGI-4, qGI-6, qGI-7 and qGI-9) with QTL Cartographer and QTLNetwork, three of them (qGI-3, qGI-7 and qGI- 9) being co-localised by both approaches. No epistasis was detected for the identified QTL but QTL-by- environment interaction was significant for qGI-7 and qGI-9. Using the single seed descendent method, families were advanced into RILs at INTA Castelar, and F6 lines were used for phenotyping in two consecutive years (2015 and 2016) at the FAUBA (Buenos Aires). A linkage map was done with 107 SNP markers, and preliminary correlation analysis identified a potential QTL on same position as qGI-9 in previous mapping populations. QTL analysis on this RIL population phenotyped under at least two environments (years) will allow the study of GXE interaction, but is also the starting point for the fine mapping of major QTL qGI-9.