Retrospective Genetic Analysis of Qualitative and Quantitative Traits in Sweet Watermelon (Citrullus lanatus var. lanatus): A Review

Abstract

Understanding the genetic basis of a crop’s qualitative and quantitative traits is vital to designing market preferred varieties. The aim of this review is to present a retrospective genetic analysis of qualitative and quantitative phenotypic traits in sweet watermelon as a guide for trait integration and the development of novel varieties with yield potential and desirable horticultural attributes. The first section outlines genes conditioning the inheritance of plant architecture (e.g., leaf attributes and plant architecture), floral characters (flowering rate, sex expression, and male sterility), fruit traits (shape, colour, rind colour and stripe patterns and flesh colour) and seed morphology (seed length, width, size and coat colour). In the second section, developments in molecular markers and quantitative trait loci (QTL) to aid marker-assisted breeding are discussed. Further, the review highlights the clustered regularly interspaced short palindromic repeats (CRISPR/Cas9) gene-editing technology and its scope in gene manipulations and new variety development. The information presented in this review is useful for optimised and demand-led breeding to develop new varieties to serve growers, consumers and the sweet watermelon industry.