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The Turnera Style S-Locus Gene TsBAHD Possesses Brassinosteroid-Inactivating Activity When Expressed in Arabidopsis thaliana
Heterostyly distinct hermaphroditic floral morphs enforce outbreeding. Morphs differ structurally, promote cross-pollination, and physiologically block self-fertilization. In Turnera the self-incompatibility (S)-locus controlling heterostyly possesses three genes specific to short-styled morph genom...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2020
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7697239/ https://www.ncbi.nlm.nih.gov/pubmed/33202834 http://dx.doi.org/10.3390/plants9111566 |
Sumario: | Heterostyly distinct hermaphroditic floral morphs enforce outbreeding. Morphs differ structurally, promote cross-pollination, and physiologically block self-fertilization. In Turnera the self-incompatibility (S)-locus controlling heterostyly possesses three genes specific to short-styled morph genomes. Only one gene, TsBAHD, is expressed in pistils and this has been hypothesized to possess brassinosteroid (BR)-inactivating activity. We tested this hypothesis using heterologous expression in Arabidopsis thaliana as a bioassay, thereby assessing growth phenotype, and the impacts on the expression of endogenous genes involved in BR homeostasis and seedling photomorphogenesis. Transgenic A. thaliana expressing TsBAHD displayed phenotypes typical of BR-deficient mutants, with phenotype severity dependent on TsBAHD expression level. BAS1, which encodes an enzyme involved in BR inactivation, was downregulated in TsBAHD-expressing lines. CPD and DWF, which encode enzymes involved in BR biosynthesis, were upregulated. Hypocotyl growth of TsBAHD dwarfs responded to application of brassinolide in light and dark in a manner typical of plants over-expressing genes encoding BR-inactivating activity. These results provide empirical support for the hypothesis that TsBAHD possesses BR-inactivating activity. Further this suggests that style length in Turnera is controlled by the same mechanism (BR inactivation) as that reported for Primula, but using a different class of enzyme. This reveals interesting convergent evolution in a biochemical mechanism to regulate floral form in heterostyly. |
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