Identification of receptor like kinase genes in coconut and development of a marker for validation of breeding materials resistant to a phytoplasma disease in Ghana

Abstract

Cape St. Paul Wilt Disease (CSPWD) is a major factor that impacts on coconut productivity in Ghana. Novel markers that might be specific for a promising variety of coconut or that could validate the efficacy of crosses would be valuable for confidence in the identity of palms. This study couples the discovery of such a marker with a high throughput genotyping system based on high resolution melt curve analysis. Using oligonucleotides designed against kinase subdomains of receptor like kinases (RLKs) of other plant species, eight putative RLK genes were isolated from coconut, and the intron sequence of one of these analysed in more detail. Three single nucleotide polymorphisms (SNPs) were identified within this intron that could be used as a tractable marker to differentiate two distinct genotypes, and which could be differentiated using high resolution melt curve analysis. Analysis of different varieties of coconut used in the breeding programme included promising hybrids such as Sri Lanka Green Dwarf x Vanuatu Tall. F1 crosses between these palms had been self pollinated to generate F2 populations. Genotyping of palms at the RLK marker suggested that some F2 offspring of parent F1 palms may have been sired via cross pollination from neighbouring palms, a possibility that would bear significance for such breeding programmes.

Key words: Coconut, genetic markers, receptor-like kinases, high resolution melt curve analysis, single nucleotide polymorphisms (SNPs).