Abstract
Main conclusion
WOX family gene WOX2 is highly expressed during seed development, which functions redundantly with WOX1 and WOX4 to positively regulate seed germination.
Abstract
WOX (WUSCHEL-related homeobox) is a family of transcription factors in plants. They play essential roles in the regulation of plant growth and development, but their function in seed germination is not well understood. In this report, we show that WOX1, WOX2, and WOX4 are close homologues in Arabidopsis. WOX2 has a redundant function with WOX1 and WOX4, respectively, in seed germination. WOX2 is highly expressed during seed development, from the globular embryonic stage to mature dry seeds, and its expression is decreased after germination. Loss of function single mutant wox2, and double mutants wox1 wox2 and wox2 wox4-1 show decreased germination speed. WOX2 and WOX4 are essential for hypocotyl–radicle zone elongation during germination, potentially by promoting the expression of cell wall-related genes. We also found that WOX2 and WOX4 regulate germination through the gibberellin (GA) pathway. These results suggest that WOX2 and WOX4 integrate the GA pathway and downstream cell wall-related genes during germination.
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All data in this study are provided in this manuscript and supplementary data files. It will be provided upon a reasonable request.
Abbreviations
- DAP:
-
Days after pollination
- GA:
-
Gibberellin
- GO:
-
Gene Ontology
- GUS:
-
β-Glucuronidase
- PAC:
-
Paclobutrazol
- WOX:
-
WUSCHEL-related homeobox
- XTH:
-
Xyloglucan endotransglucosylase/hydrolase
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The authors thank Dr. Galal Mabrouk very much for his great help improve the manuscript. This work was supported by grants from the National Natural Science Foundation of China (31870305, 32270353, and 32170355).
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YXL and HC planned and designed the research. YY, ZR, and LL conducted the experiments. YL and YH contributed materials and analysis tools. YY, ZR, YXL, and HC analyzed the data. YY and HC wrote the manuscript. YXL and HC revised the manuscript. All authors read and approved the manuscript.
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Supplementary file 1—Supplementary Fig. S1. Relative transcript abundance of the WOX family genes in dry, stratified, and germinating seeds, and seedlings. a–l The expression levels of WOX4, WOX6, WOX7, WOX5, WOX9, WOX11, WOX12, WOX13, WOX1, WOX2, WOX10, and WOX14 in dry, stratified, and germinating seeds, and seedlings. UBIQUITIN5 was used as an internal control for the normalization of gene expression. Values are means of three biological replicates. The error bars represent SE. Dry seeds, seeds stratified for 24 h, 48 h, and 72 h, seeds germinated for 8 h, 16 h, and seedlings germinated for 24 h, were collected for total RNA extraction. Fig. S2. Phylogenetic analysis of the Arabidopsis WOX family. The unrooted trees were inferred by the neighbor-joining method after the alignment of the protein sequences of the 15 Arabidopsis WOXs. WOX1, WOX2, and WOX4 are highlighted with the red box. Evolutionary analysis was conducted in the TBtools program. Fig. S3. Seed dormancy phenotypes of wild-type Col and wox mutants. a Germination after different dry storage periods of wild type (Col), wox2, and wox2-3. b Germination after different dry storage periods of Col, wox1, wox2, and wox1 wox2. c Germination after different dry storage periods of Col, wox2, wox4-1, and wox2 wox4-1. Seeds were stored at room temperature for after-ripening. Percentages of seed germination are means (± SE) based on at least eight individual plants for each genotype. Fig. S4. wox2 wox4-1 double mutant seedlings display a range of cotyledon phenotypes. a Six-day-old wild-type (Col) seedling with two normal cotyledons. b–e Six-day-old wox2 wox4-1 seedlings with two cotyledons positioned at an angle (b), two cotyledons of unequal size (c), single cotyledon (d) and heart-shaped cotyledon (e). Bars = 1 mm. Fig. S5. Total RNA was isolated from seeds imbibed for 18 h of wild type and wox2 wox4-1 for RNA-seq. Imbibition for 18 h was the first time point at which the germination of wox2 wox4-1 was significantly lower than that of Col. Seeds were stratified at 4 °C for 3 days before the germination experiment. Values are the means ± SE based on the seeds from six to eight individual plants for each genotype. The double asterisk indicates a significant difference compared to the wild type as determined by Student’s t-test (**P < 0.01). Fig. S6. Pathway enrichment analysis of DEGs in the boxes-marked pathways in Fig. 5a. XTHs genes are highlighted with the red box. The dot size is proportional to the gene number. The color scale indicates the significance level. (DOCX 1885 KB)
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Yang, Y., Ren, Z., Li, L. et al. WOX2 functions redundantly with WOX1 and WOX4 to positively regulate seed germination in Arabidopsis. Planta 259, 83 (2024). https://doi.org/10.1007/s00425-024-04357-7
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DOI: https://doi.org/10.1007/s00425-024-04357-7