Identifying positional candidate genes controlling low vicine-convicine in faba bean (Vicia faba L.)

Abstract

Trabajo presentado en la International Conference Advances in grain legume breeding, cultivation and uses for a more competitive value-chain, celebrada en Novi Sad (Serbia) el 27 y 28 de septiembre de 2017.Vicine and convicine (v-c) are faba bean compounds with anti-nutritional effects in monogastric animals and potential toxicity in humans. A single gene, vc-, responsible for a 10-20 fold reduction (1, 2) was identified and several attempts to identify candidate genes (3, 4) have been pursued. The approach is limited by its reliance on the priori knowledge about the physiological function of candidates. In case of v-c, the lack of knowledge of the v-c synthetic pathway, the large faba bean genome size (~13 Gbp) and the lack of a reference genome, result in a significant bottleneck for the application of this approach. Although the task is challenging, significant progress has been achieved within LEGA TO and several closer markers have been identified. To determine which enzymes or transcriptional factors could be encoded by the vc-gene, we have used comparative genomic approaches (5), KASPar SNP genotyping assays (6) and high-throughput genome profiling DarTSeq (7) in a F2 from the cross Vf6 x vc-, to generated a map with more than 4000 markers. The target region was confined between Medtr2g008210 and Medtr2g010180, containing 136 genes, but the causative gene remains unknown. Recently, 21 new candidates have been genotyped in the population, using the Medicago and the faba bean transcriptome sequences (8). Fourteen should be discarded due to nonspecific/lack of amplification or to the absence of SNPs in the target sequence. The remaining seven could bemapped, thus providing potential candidate genes and offering a step towards breeding lines free of these compoundsN