Induced mutagenesis to augment the natural genetic variability of melon (Cucumis melo L.)

Abstract

Induced mutagenesis of agricultural crops creates new variation in genes, including those affecting agriculturally important traits such as plant morphology and fruit quality. Melon (Cucumis melo L.) is a diploid species (2n = 24) with a small genome, estimated as 450 Mb, but with relatively high levels of sequence and fruit shape polymorphism. We treated seeds of ‘Noy Yizre'el’, a ‘Galia’ melon-type parental line, with the chemical mutagen EMS (ethyl methane sulfonate). The resulting M₁ plants were self-pollinated to produce about 3,000 M₂ families, segregating for the induced mutations that we regard as a "mutation library". Phenotypic analyses revealed newly induced variation, mostly governed by single recessive mutations, affecting different plant organs, including cotyledon, leaves, flowers, and fruit, at different growth stages, from emergence to mature fruit. Several mutations show phenotypic similarities to mutations found in other plant species. Further studies are required to determine whether the same gene had been mutated in both species, indicating functional homology.

This mutation library is an important source for new traits. Some of the identified mutants have already been incorporated into our breeding program. Moreover, the melon mutation library serves as an essential infrastructure for the discovery of important genes, for the annotation of unknown sequences, and for phenotypic and genetic comparison with mutation libraries of other plant species.

Keywords:

• Cucumis melo L.
• EMS mutagenesis
• mutation library
• functional homology