Characterization of a sex-determining locus and development of early molecular assays in Telfairia occidentalisHook. F., a dioecious cucurbit

Abstract

Although there exist over 7000 crop species, only a few are commercially valuable and grown on a large scale in monocultures worldwide. However, underutilised crops (also called orphan crops) have significant potential for food security and Telfairia occidentalis Hook. F. (Cucurbitaceae) is one such orphan crop grown in West Africa for its nutritious leaves, oil and protein-rich seeds. In this dioecious crop, farmers like to eliminate male plants and keep mostly females to increase their yield. However, they face the challenge of determining sex due to limited morphological differences between females and males before flowering. This study used double digested restriction site-associated DNA sequencing data (ddRADseq) to examine the genetic diversity within and among landraces of T. occidentalis , identify common sex-determining loci, and establish reliable assays to characterize the sex of immature plants in the vegetative state. To differentiate males from females of T. occidentalis , two molecular assays were thereupon developed based on polymerase chain reaction (PCR) to genotype sex-specific sequence variation either through restriction by Mfe1 or the direct use of sex-specific primers. Both assays require standard laboratory conditions to reach a certainty of 94.3% for females and 95.7% for males from the studied samples. With the inclusion of additional landraces, medium to largescale farms growing T. occidentalis as a crop can readily benefit from an early determination of the sex of plants.

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