A Gene Encoding Xylanase Inhibitor Is a Candidate Gene for Bruchid ( spp.) Resistance in Zombi Pea ( (L.) A. Rich).

Two bruchid species, and , are the most significant stored insect pests of tropical legume crops. Previously, we identified a major QTL, , controlling seed resistance to these bruchids in the cultivated zombi pea () accession 'TVNu 240'. In this study, we have narrowed down the region and identified a candidate gene conferring this resistance. Fine mapping using F and F populations derived from a cross between TVNu 240 and TVNu 1623 (susceptible) revealed the existence of two tightly linked QTLs, designated and , within the . The QTLs and explained 37.46% and 10.63% of bruchid resistance variation, respectively. was mapped to a 28.24 kb region containing four genes, from which the gene encoding a xylanase inhibitor was selected as a candidate gene responsible for the resistance associated with the . Sequencing and sequence alignment of from TVNu 240 and TVNu 1623 revealed a 1-base-pair insertion/deletion and five single-nucleotide polymorphisms (SNPs) in the 5' UTR and 11 SNPs in the exon. Alignment of the VvTAXI protein sequences showed five amino acid changes between the TVNu 240 and TVNu 1623 sequences. Altogether, these results demonstrated that the encoding xylanase inhibitor is the candidate gene conferring bruchid resistance in the zombi pea accession TVNu 240. The gene will be useful for the molecular breeding of bruchid resistance in the zombi pea.