Prospects of mutation breeding in grapefruit (Citrus paradisi Macf.)

Abstract

Grapefruit is considered as a minor citrus crop in Pakistan and its annual production is less than 0.5% of total citrus production. Grapefruit industry is depending upon pink flesh cultivar ‘Shamber’ and need varietal diversification. Mutation breeding has played a pivotal role in grapefruit crop improvement and most of the commercial cultivars are bud sports or induced mutants which were selected and later released as new cultivars. Flesh color enhancement, seedlessness and low furanocoumarin level have been main objectives for grapefruit breeders. An overview of potential of mutation breeding in grapefruit and leading mutants produced is presented in the following sections. Though physical mutagens have been more successful, breeders’ interest is rising in more precise and targeted mutagenesis technologies including CRISPR/Cas9 which has enormous potential in genome editing and could shorten breeding and selection cycle. The available leading grapefruit cultivars were screened for horticultural traits and potential candidate varieties has been selected for diversification and selection of better parents for breeding programs. Several putative mutants have been developed using gamma irradiated plant material. The effect of irradiation on plant growth, morphology and biochemical properties has been evaluated and salient findings are discussed. The developed genetically diverse material could be useful for future biotechnology applications.