Plant biomass is an important agronomic trait that has been subjected to intense human selection for yield improvement. The underlying mechanism regulating biomass formation is currently gaining increasing attention, but it remains unexplored. In this study, we isolated a cucumber (Cucumis sativus L.) minicuke mutant with remarkably reduced biomass. The causative gene was identified as CsNMT1, a homologue of the Arabidopsis thaliana N-myristoyltransferase1. Our clustered regularly interspaced shot palindromic repeat-based genome editing confirmed the key role of CsNMT1 in biomass regulation. Multi-omics analyses integrating metabolomic and transcriptomic analyses revealed the suppression of a very early step of lignin biosynthesis and the corresponding down-regulation of genes involved in lignin biosynthesis in the minicikue mutant, suggesting an unexpected pathway for regulating biomass accumulation through lignin sink strength. Our findings demonstrate the function of NMT1 in regulating plant biomass and its potential application value for biomass improvement in cucurbits.

Thigmotropism and thigmomorphogenesis are two related and pervasive processes that play crucial roles in plant adaptation to the environment. However, there have been few investigations into the molecular regulatory mechanisms of these phenomena. Cucumber (Cucumis sativus L.) tendrils are ideal material for studying thigmotropism and thigmomorphogenesis because they display a combination of the two processes. Here, we generated the transcriptome profiles of cucumber tendrils at the young, stretch, and coiling stages. Genes related to receptor proteins, transmembrane transport, and ion transport were significantly enriched among those differentially expressed between stages. Pharmacological assays illustrated that three GLUTAMATE RECEPTOR (GLR) genes might play a vital function in perceiving or transducing touch stimulation signals. Comparing the transcriptomes of tendrils and roots after touch stimulation, we found that genes related to extracellular stimulus and xyloglucan metabolism might have conserved functions in the regulation of thigmomorphogenesis. The transcriptome atlas of thigmotropism and thigmomorphogenesis of cucumber tendrils constructed in this study will help further elucidate the molecular mechanisms behind these processes.