DArTseq Molecular Markers Associated with the Spiny-Tip Leaf Margin in Pineapple (Ananas comosus L.)

Abstract

A genome-wide association study (GWAS) and quantitative trait loci (QTL) analysis using two bi-parental (parental cultivars Smooth Cayenne and MD-2) pineapple seedling populations segregating for spiny and spiny-tip leaf margin and 12 wild and pre-Columbian domesticated genotypes were used to identify single nucleotide polymorphism (SNP) and silicoDArT markers associated with the spiny-tip leaf margin phenotype in pineapple. One QTL between the nucleotide positions 14,355,639 and 14,368,806 on linkage group six (LG06) was identified using SNP markers and one QTL between the nucleotide positions 14,330,844 and 14,346,378 using silicoDArT markers. GWAS and QTL analysis methods identified the same most significantly associated SNP and silicoDArT markers. The most significantly associated SNP and silicoDArT markers were positioned at 14,355,639 and 14,341,745 bp respectively, on or very near, a zeaxanthin epoxidase (ZEP) gene, a key gene in the abscisic acid (ABA) pathway. Other associated genes with a high significance by GWAS analysis using at least two algorithms include a detoxification 33-like (DTX) and a resistance gene analog (RGA2-like). It is proposed that a polymorphism in the putative ZEP gene is the main causal variant associated with the spiny-tip leaf margin in ‘Smooth Cayenne’ pineapple and its descendants including ‘MD-2’.