HsGA20ox1, HsGA3ox1, and HsGA2ox1 Are Involved in Endogenous Gibberellin Regulation Within Heracleum sosnowskyi Ovaries After Gibberellin A3 Treatment

Abstract

This study aims to investigate the endogenous gibberellin levels and related genes analysis of noxious invasive weed Heracleum sosnowskyi. Genome-wide identification, phylogenetic analysis, conserved motif analysis, and gene structure characterization of GA-oxidases were performed. We analysed endogenous GAs levels and the expression of target HsGAoxs in response to GA₃ within H. sosnowskyi developing ovaries. Twenty-seven HsGAoxs genes were identified, distributed across eleven chromosomes. Phylogenetic analysis classified proteins into the HsGA20ox, C₁₉-HsGA2ox, and HsGA3ox subfamilies, facilitating functional predictions. Among the thirteen HsGA2ox protein members, there were no C₂₀-GA2ox subfamily that distinguish H. sosnowskyi from other model plant species. The analysis of gene structure and conserved motifs confirmed the phylogenetic grouping and suggested that the evolutionary pattern was maintained within these subfamilies. The observed increase in precursor and bioactive GA levels provides evidence that they play a crucial role in promoting fruit growth. Ovary phenotypes reflected the timing of peak gibberellin levels, specifically during the cell expansion period. Exogenous GA₃ treatment promoted HsGA3ox1 expression within both the central and lateral regions of the umbel ovaries. Overall, the results show that GA levels are precisely regulated by multiple HsGAox genes for stable early fruit development, and that disturbances in this stability affect fruit development. This opens up the possibility of investigating the role of GA in H. sosnowskyi fruit formation and developing measures for invasion control.

Keywords: 2-oxoglutarate-dependent dioxygenases; Apiaceae; Sosnowsky’s hogweed; early fruit development; genome-wide analysis; gibberellic acid; invasive plant.

Figure 1

Distribution of HsGAox genes on Heracleum sosnowskyi chromosomes. The scale refers to the lengths of the chromosomes.

Figure 2

The phylogenetic relationship analysis of GAox proteins among Heracleum sosnowskyi, Arabidopsis thaliana, and Oryza sativa. The tree was constructed according to the ML method, using MEGA 12.0 software with 500 bootstrap replicates. The GAox subfamilies and analyzed species were labeled with different colors. Scale bar refers to a phylogenetic distance of amino acid substitutions per site.

Figure 3

Representation of conserved protein domains, motifs, and gene structure patterns of Heracleum sosnowskyi GAox. (A) Generated models of putative HsGA20ox1, HsGA20ox2, HsGA2ox1, and HsGA3ox1 proteins. Non-haem dioxygenase N-terminal and 2OG-Fe(II) oxygenase domains are highlighted in dark blue and light blue, respectively. (B) Schematic view of HsGAox protein sequences and 10 conserved motifs distributed among them. (C) The gene structure map of HsGAox members.

Figure 4

Schematic picture of Heracleum sosnowskyi terminal inflorescence (A). The effect of 150 mg/L gibberellic acid (GA₃) on GA biosynthesis gene expression (B), endogenous gibberellin (GA) content (C), phenotype (D), and morphometry (E) in H. sosnowskyi ovary tissues from the central and lateral parts of terminal inflorescence. DAA—days after application GA₃. Error bars represent the standard error of the mean. Asterisks in the same color columns indicate statistically significant differences (*—p < 0.01; **—p < 0.001). Scale bar represents 1 mm.