Desenvolvimento da plataforma DART e mapeamento de locos associados com tolerância à seca em feijão (Phaseolus vulgaris L.)

Abstract

Common bean (Phaseolus vulgaris L.) is the most important food legume for consumption and for exportation. Drought is one of the main abiotic stresses in the world and affects about 60% of bean growing area across the world. The advance in technologies of molecular markers provide a powerful method to examine the relationships between traits, generating large amount of potentially useful information to assist the breeding programs. The objective of this project was the development of DArT platform for common beans with DArT Pty Ltd and the mapping of these markers with microsatellites and SNPs in the population AND 277 x SEA 5 from CIAT (Colombia), in order to locate the QTLs associated with drought tolerance. The SEA 5 parent is a drought tolerant advanced line (Mesoamerican) and the AND 277 is resistant to the angular leaf spot and antracnose (Andean). A total of 4.468 DArT markers, 288 SNP and 180 SSR polymorphic markers were identified in the population and used in genotyping to constructed a saturated genetic map. Phenotyping of 105 recombinant inbred lines (RILs) in F 8 generation plus the genitors were performed evaluating 18 traits associated with drought tolerance using a completely randomized design with four replicates, applying terminal stress at vegetative phase V3/V4. Two maps were constructed, one integrating 80 SSR and 251 SNPs and another with five SSR, 91 SNPs and 4,468 DArTs. The identification of QTL analysis was performed by composite interval mapping (CIM) for the SSR -SNPs map and the precision mapping (SML) to map DArT-SSR-SNPs. A total of 12 QTLs were identified for the non-irrigated treatment and 29 QTLs for the irrigated treatment by CIM analysis. For SML analysis, 23 QTLs were identified for the non-irrigated and 11 QTLs for irrigated treatment. QTLs of major effect was found for chlorophyll, fresh biomass of stem and leaf dry weight, leaf temperature, number of pods, number of seeds, seed weight, days to flowering, dry weight of pods and yield in both treatments. All QTLs detected under dry conditions showed the allele of parent SEA 5. This study is important for genetic improvement not only to better understand the genetic inheritance of a trait as complex as drought tolerance, as well as to find molecular tools to be used for marker assisted selection.