Changes in plasma membrane aquaporin gene expression under osmotic stress and blue light in tomato
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Divergent abiotic stresses induce osmotic stress on plant cells resulting in an imbalance in water homeostasis which is preserved by aquaporins. Since the plasma membrane aquaporins (PIPs) were shown to be involved in seed development and responses to abiotic stresses, we focused on determining the contribution of mannitol-induced osmotic stress, blue light (BL), and 7B-1 mutation to their gene expression in tomato (Solanum lycopersicum L.) seeds. To assess that, we used a quantitative RT-PCR to determine the expression profiles of genes encoding PIPs. Subsequently, a multiple linear regression analysis was used to evaluate the impact of studied stressors (mannitol and BL) and 7B-1 mutation on PIP gene expressions. We found that mannitol-induced osmotic stress and 7B-1 mutation (conferring the lower responsiveness to osmotic stress- and BL-induced inhibition of seed germination) decreased expression of PIP1;3, PIP2;3 and PIP1;2, PIP2;1 genes, respectively. This might be a way to retain water for radicle elongation and seed germination under the stress conditions. Interestingly, the expression of PIP1;3 gene was downregulated not only by osmotic stress, but also by BL. Altogether, our data indicate the existence of a link between osmotic stress and BL signalling and the involvement of the 7B-1 mutation in this crosstalk.
KeywordsTomato Seed Aquaporins Blue light 7B-1 mutant Mannitol PIPs
The authors thank Tomáš Fürst for the critical comments about statistical analysis. We thank Renáta Plotzová and Věra Chytilová for technical assistance. We thank Vipen K. Sawhney for providing 7B-1 mutant seeds and Jan Nauš for measurements of the PFD of the light. This work was supported by Ministry of Education, Youth and Sports of the Czech Republic (Project Nos. ME10020 and LO1204) and Operational Programs Education for Competitiveness-European Social Fund (Project No. CZ.1.07/2.3.00/30.0004).
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