WUSCHEL-Related Homeobox1 (WOX1) regulates vein patterning and leaf size in Cucumis sativus

Authors: WANG, HU - Northwest Agricultural & Forestry University; NIU, HUANHUAN - Northwest Agricultural & Forestry University; LI, CHUANG - Northwest Agricultural & Forestry University; SHEN, GUOYAN - Northwest A&f University; LIU, XIAOFENG - China Agricultural University; Weng, Yiqun; WU, TAO - Hunan Agricultural University; LI, ZHENG - Northwest Agricultural & Forestry University

Submitted to: Horticulture Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2020
Publication Date: 11/1/2020
Citation: Wang, H., Niu, H., Li, C., Shen, G., Liu, X., Weng, Y., Wu, T., Li, Z. 2020. WUSCHEL-Related Homeobox1 (WOX1) regulates vein patterning and leaf size in Cucumis sativus. Horticulture Research. (2020) 7:182. https://doi.org/10.1038/s41438-020-00404-y.
DOI: https://doi.org/10.1038/s41438-020-00404-y

Interpretive Summary: Background information: A cucumber mango fruit (mf) mutant displays mango shaped fruit, and defective leaf development. We previously found that this mutant appearance is caused by a mutation in the gene that encodes a truncated WOX1-type protein (CsWOX1), but the reason why the mutant develops striped leaves is unknown. Findings: In this study, we compared the leaf structure of the mutant and normal plants under an electronic microscope. We conducted RNA in situ hybridization, and examined ectopic expression of CsWOX1 in Arabidopsis and cucumber plants. We also developed cucumber round leaf (rl) mf double mutant to identify the function of CsWOX1. Additional work was conducted to identify interacting partners with CsWOX1, and the regulatory network of the CsWOX1 gene. We found that CsWOX1 expresses in the middle mesophyll and leaf margin, and rescues defects of the wox1 prs double mutants in Arabidopsis. The mf mutant exhibits an unbalance growth between vein and lamina. Overexpressing CsWOX1 in cucumber (CsWOX1-OE) affects primary vein patterning. We also show that CsWOX1 functions via the auxin pathway. CsWOX1 interacts with CsTCP4a, which may result in the abnormal lamina development in the mf mutant and smaller leaves in the CsWOX1-OE line. Finally, CsWOX1 regulates the normal leaf development by patterning the normal establishment of leaf veins depending on the auxin polar transport; meanwhile, CsWOX1 stabilizes the leaf size via controlling CIN-TCP genes. Who cares? Results from this study are of interest to plant development biologist to understand the molecular mechanism of organ development in cucumber.

Technical Abstract: 1. A cucumber mango fruit (mf) mutant displays defect in leaves. We previously showed that the mutant is the result of a truncated WOX1-type protein (CsWOX1). In this study, we revealed the critical roles of CsWOX1 in palmate leaf expansion of cucumber. 2. Herein, mf mutant phenotyping was conducted with section and SEM assays. in situ hybridization (ISH) analysis, ectopic expression of CsWOX1 in Arabidopsis and cucumber plants, and developing cucumber round leaf (rl) mf double mutants were used to identify the function of CsWOX1. RNA-Seq, Y2H, and BiFC were conducted for gene interaction analysis. 3. CsWOX1 expresses in the middle mesophyll and leaf margin, and rescues defects of the wox1 prs double mutants in Arabidopsis. The mf mutant exhibits an unbalance growth between vein and lamina. Overexpressing CsWOX1 in cucumber (CsWOX1-OE) affects primary vein patterning. CsWOX1 functions via the auxin pathway, and acts upstream of CsPID1. CsWOX1 interacts with CsTCP4a, which may result in the abnormal lamina development in the mf mutant and smaller leaves in the CsWOX1-OE line. 4. CsWOX1 regulates the normal leaf development by patterning the normal establishment of leaf veins depending on the auxin polar transport; meanwhile, CsWOX1 stabilizes the leaf size via controlling CIN-TCP genes.