Abstract
BASIC PENTACYSTEINE (BPC) is a small transcription factor family that functions in diverse growth and development processes in plants. However, the roles of BPCs in plants, especially cucumber (Cucumis sativus L.), in response to abiotic stress and exogenous phytohormones are still unclear. Here, we identified four BPC genes in the cucumber genome, and classified them into two groups according to phylogenetic analysis. We also investigated the gene structures and detected five conserved motifs in these CsBPCs. Tissue expression pattern analysis revealed that the four CsBPCs were expressed ubiquitously in both vegetative and reproductive organs. Additionally, the transcriptional levels of the four CsBPCs were induced by various abiotic stress and hormone treatments. Overexpression of CsBPC2 in tobacco (Nicotiana tabacum) inhibited seed germination under saline, polyethylene glycol, and abscisic acid (ABA) conditions. The results suggest that the CsBPC genes may play crucial roles in cucumber growth and development, as well as responses to abiotic stresses and plant hormones. CsBPC2 overexpression in tobacco negatively affected seed germination under hyperosmotic conditions. Additionally, CsBPC2 functioned in ABA-inhibited seed germination and hypersensitivity to ABA-mediated responses. Our results provide fundamental information for further research on the biological functions of BPCs in development and abiotic stress responses in cucumber and other plant species.
Highlights
Cucumber (Cucumis sativus L.) is a major vegetable crop worldwide and has served as a model system for studies on sex determination [1] and plant vascular biology [2]
We found that cucumber BASIC PENTACYSTEINE (BPC) are involved in seed germination as regulators of ABSCISIC ACID INSENSITIVE3 (ABI3) [21]
The results revealed that all four cucumber BPC genes were ubiquitously expressed in all the tissues tested, and that they shared the highest expression levels in seeds and the lowest levels in tendrils and stems (Figure 4), which may suggest a vital role for the CsBPCs in cucumber growth and development processes and, in seed development
Summary
Cucumber (Cucumis sativus L.) is a major vegetable crop worldwide and has served as a model system for studies on sex determination [1] and plant vascular biology [2]. Multiple BPC allele mutants displayed pleiotropic developmental defects, including dwarfism, small rosettes, early flowering, aberrant ovules, unopened floral buds, and even high sterility [12,13,14,15] The reason for these morphological changes may be that BPCs bind to and regulate the activities and expression levels of target genes associated with development. Their predicted gene structures and conserved motifs were subsequently analyzed We investigated their expression patterns in various tissues and in response to different stresses and plant hormones by qRT-PCR. Expression Patterns of the CsBPC Genes under Different Abiotic Stress and Phytohormone Treatments. Under the NaCl, PEG, and cold treatments, the expression levels of CsBPC2 in roots or leaves increased by a maximum of 6.1-, 6.1-, and 1.7-fold, respectively, the most among the four genes. 16.0%, respectively, which were dramatically lower than that of WT (95.33%) (Figure 9C,F)
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