Molecular markers associated with leaf expansion response to water deficit conditions.

ALBERDI, I; PEREYRA IRUJO, G.A; ZAMBELLI, A; KASPAR, M; FEINGOLD S.; ALVAREZ, D; AGUIRREZÁBAL L.A.N

Mar del Plata

Conferencia; 18 th International Sunflower Confernece; 2012

ASAGIR - ISA

ABSTRACT • Water deficit is one of the major constraints to crop yields worldwide. In this context, adaptation of genotypes to different water regimes is a key factor to ensure yield stability. An underlying response that seems to regulate the degree of decrease in yield is leaf expansion before anthesis. Progeny studies together with molecular marker technology would allow for this character to be mapped. The present work aims at studying the relationship between a set of molecular markers (AFLP and SSR) and leaf expansion parameters under water deficit conditions in a cross of two public sunflower lines of contrasting response, in its F2 (data from a previous work) and F2:3 progenies, and in an independent F¬8 recombinant inbred line (RIL) population. • Phenotyping trials were carried out in three different experiments, two of them in growth chambers (F2 and F2:3) and one in a greenhouse (RIL population). Plants were grown in cylindrical 2.7 l pots filled with soil, and a standardized method was used to generate water deficit conditions. Leaf expansion data were collected, and then processed to obtain parameters of leaf growth. DNA was extracted from F2 individuals and RILs. A set of 60 SSR and 41 AFLP markers was evaluated in the F2 population, whereas 68 SSR where evaluated for the RILs. Single marker analysis was performed associating genotype data from F2 individuals and phenotype data from F2 individuals and F2:3 families • A genomic region was identified which contains one stable marker significantly associated with the response of leaf growth to water deficit in the three generations of the cross (maximum significance: p=0.02, p=0.03 and p=0.003 in F2, F2:3 and RILs, respectively). • These results confirm the previous findings, and provide evidence on the stability of a region of the genome associated to the response of leaf expansion to water deficit in sunflower. The nature of an F2 population (individuals with unique genotypes) imposes limitations to characterize responses to water deficit, so a single-plant approach had to be used for that generation, while an experimental design with control and stressed plants could be used for RILs and F2:3. The consistency of the identified genetic markers suggests that outputs of both phenotyping methods could be comparable. • This information could be useful to develop molecular makers for assisted selection in breeding programs oriented to generate new cultivars with improved adaptation to water stress conditions. A dissection of this analysis into a single leaf approach is being carried out in order to achieve a more specific phenotype characterization under water stress conditions. Association of leaf expansion parameters of leaves at different growth stages at the moment of the stress treatment might allow a more precise identification of QTL associated with leaf expansion response.