CRISPR/Cas9-mediated knockout of SPL13 radically increases lettuce yield

Abstract

Cultivated lettuce (Lactuca sativa L.) is a diploid(2n=2x=18), autogamous species. This popular leafy vegetable is considered one of the frst crops (Guo et al. 2022).Currently, lettuce is the third most consumed leafy vegetable worldwide (FAO 2020). In addition, this crop is usedin molecular farming due to its low cost and highly scalable biomass production, low processing cost and excellentbiosafety profle of the modifed plants expressing diferenttransgenes (Darqui et al. 2021; Zhang et al. 2019). Althoughconventional varieties of lettuce with varying degrees of tolerance to both biotic (e.g. pests and diseases) and abiotic(e.g. drought and salinity) stresses have been developed, conventional approaches have been unable to produce lettucecultivars with considerably increased yields (Damerum et al.2020; Wei et al. 2021). Recently, CRISPR/Cas9-mediatedknockout of the transcriptional factor SOC1 has resulted ina delay of 6 days in the appearance of the frst fower bud,displaying the potential use of genome editing to increaselettuce yield and opening the way for a new generation ofmodifed lettuce varieties (Choi et al. 2022).In alfalfa, the RNAi-mediated silencing of the transcriptional factor SPL13 causes increased vegetative shootbranches and delayed fowering time (Gao et al. 2018). Toexpand the benefts of genome editing to lettuce species,we here produced three independent mutant lines withan editing plasmid containing three sgRNAs against the SPL13 gene.