GENE EDITING IN THE DEVELOPMENT OF CUCUMBER HYBRIDS FOR GREENHOUSE CULTIVATION: THE SIGNIFICANCE OF CRISPR/Cas9 AND ITS NEXT-GENERATION TOOLS

Abstract

Greenhouse production of cucumber (Cucumis sativus L.) requires hybrids that combine stable femaleness, parthenocarpy, durable disease resistance and high fruit quality, whereas conventional breeding of such hybrids is slow. This review summarises the CRISPR/Cas9 toolbox and its next-generation derivatives (Cas12a, Cas13, base editors, prime editors and dCas-based regulators) and maps published studies onto the key greenhouse traits: gynoecy (CsWIP1, CsACS), parthenocarpy, resistance to powdery mildew (CsaMLO8, CsaMLO1/11), potyviruses (eIF4E) and downy mildew, and non-bitter fruit (Bi, Bl, Bt). The integration of editing into hybrid seed production and the main constraints (transformation efficiency, off-target risk, delivery and regulation) are discussed. Combined with speed breeding and genomics-assisted selection, these tools can substantially shorten the development of greenhouse cucumber hybrids.