The spines and bloom of cucumber (Cucumis sativus L.) fruit are two important quality traits related to fruit market value. However, until now, none of the genes involved in the formation of cucumber fruit spines and bloom trichomes has been identified. Here, the characterization of trichome development in wild-type (WT) cucumber and a spontaneous mutant, glabrous 1 (csgl1) controlled by a single recessive nuclear gene, with glabrous aerial organs, is reported. Via map-based cloning, CsGL1 was isolated and it was found that it encoded a member of the homeodomain-leucine zipper I (HD-Zip I) proteins previously identified to function mainly in the abiotic stress responses of plants. Tissue-specific expression analysis indicated that CsGL1 was strongly expressed in trichomes and fruit spines. In addition, CsGL1 was a nuclear protein with weak transcriptional activation activity in yeast. A comparative analysis of the digital gene expression (DGE) profile between csgl1 and WT leaves revealed that CsGL1 had a significant influence on the gene expression profile in cucumber, especially on genes related to cellular process, which is consistent with the phenotypic difference between csgl1 and the WT. Moreover, two genes, CsMYB6 and CsGA20ox1, possibly involved in the formation of cucumber trichomes and fruit spines, were characterized. Overall, the findings reveal a new function for the HD-Zip I gene subfamily, and provide some candidate genes for genetic engineering approaches to improve cucumber fruit external quality.
The WD-repeat (WDR) proteins comprise an astonishingly diverse superfamily of regulatory proteins. To date, genome-wide characterization of this family has only been conducted in Arabidopsis and little is known about WDR genes in cucumber (Cucumis sativus L.). This study identified 191 cucumber WDR genes in the latest cucumber genome and the CsWDR family contained a smaller number of identified genes compared to Arabidopsis. The results of this study were also supported by genome distribution and gene duplication analysis. Phylogenetic analysis showed that the WDR proteins could be classified into 21 subgroups. Moreover, an additional 12 AtWDR proteins were also identified and a complete overview of this gene family in Arabidopsis is presented, including the phylogeny, chromosome locations and duplication events. In addition, a comparative analysis between these genes in cucumber and Arabidopsis was performed and it suggested that there was strong gene conservation and that there was an expansion of particular functional genes during the evolution of the two species. The transcript abundance level analysis during abiotic stress (NaCl, ABA and low temperature treatments) identified six CsWDR genes that responded to one or more treatments. Tissue-specific expression profiles of these six genes were also analyzed. This study has produced a comparative genomics analysis of the WDR gene family in cucumber and Arabidopsis and provides the first steps towards the selection of CsWDR genes for cloning and functional dissection that can be used in further studies into their roles in cucumber stress resistance.
BackgroundThe R2R3MYB proteins comprise one of the largest families of transcription factors in plants. Although genome-wide analysis of this family has been carried out in some species, little is known about R2R3MYB genes in cucumber (Cucumis sativus L.).Principal FindingsThis study has identified 55 R2R3MYB genes in the latest cucumber genome and the CsR2R3MYB family contained the smallest number of identified genes compared to other species that have been studied due to the absence of recent gene duplication events. These results were also supported by genome distribution and gene duplication analysis. Phylogenetic analysis showed that they could be classified into 11 subgroups. The evolutionary relationships and the intron - exon organizations that showed similarities with Arabidopsis, Vitis and Glycine R2R3MYB proteins were also analyzed and suggested strong gene conservation but also the expansions of particular functional genes during the evolution of the plant species. In addition, we found that 8 out of 55 (∼14.54%) cucumber R2R3MYB genes underwent alternative splicing events, producing a variety of transcripts from a single gene, which illustrated the extremely high complexity of transcriptome regulation. Tissue-specific expression profiles showed that 50 cucumber R2R3MYB genes were expressed in at least one of the tissues and the other 5 genes showed very low expression in all tissues tested, which suggested that cucumber R2R3MYB genes took part in many cellular processes. The transcript abundance level analysis during abiotic conditions (NaCl, ABA and low temperature treatments) identified a group of R2R3MYB genes that responded to one or more treatments.ConclusionsThis study has produced a comparative genomics analysis of the cucumber R2R3MYB gene family and has provided the first steps towards the selection of CsR2R3MYB genes for cloning and functional dissection that can be used in further studies to uncover their roles in cucumber growth and development.
Flavonols and proanthocyanidins (PAs) are the main pigments in the black spines of cucumber (Cucumis sativus) fruit, and CsMYB60 is a key regulator of the biosynthesis of flavonols and PAs. However, in cucumber, the tissue distribution pattern of flavonols and PAs and the mechanism of their biosynthesis regulated by CsMYB60 remain unclear. In this study, we clarified the tissue-specific distribution of flavonoids and the unique transcriptional regulation of flavonoid biosynthesis in cucumber. CsMYB60 activated CsFLS and CsLAR by binding to their promoters and directly or indirectly promoted the expression of CsbHLH42, CsMYC1, CsWD40, and CsTATA-box binding protein, resulting in the formation of complexes of these four proteins to increase the expression of Cs4CL and interact with CsTATA-box binding protein to regulate the expression of CsCHS, thereby regulating the biosynthesis of flavonols and PAs in cucumber. Our data provide new insights into the molecular mechanism of flavonoid biosynthesis, which will facilitate molecular breeding to improve fruit quality in cucumber.
Spine color is an important fruit exterior quality trait influencing the commercial value of cucumber (Cucumis sativus L.). However, little is known about the metabolites and the regulatory mechanisms of their biosynthesis in black spine. Here, we found that the pigments of black spine are flavonoids including flavonols revealed by HPLC (High Performance Liquid Chromatography), MS (Mass Spectrometry) and NMR (Nuclear magnetic resonance) analysis, and proanthocyanidins (PAs) revealed by DMACA staining and MS analysis. Available data indicate that CsMYB60 is the best candidate for B (Black spine). The expression levels of CsMYB60 and the key genes involved in flavonoid biosynthesis are higher in black spine than that in white spine at different developmental stages. The insertion of a Mutator-like element (CsMULE) in the second intron of CsMYB60 decreased its expression in the white spine line. Transient overexpression assay indicated that CsMYB60 is a key regulatory gene and Cs4CL a key structural gene in the pigmentation of black spines. Moreover, DNA methylation level in the CsMYB60 promoter is much lower in black spine compared with white spine. Together, the CsMULE insert might result in the decrease of CsMYB60 expression, which causes hindered synthesis of flavonols and PAs in cucumber fruit spine.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.