Expression Patterns and Promoter Activity of a Gene Encoding a Eucalyptus Aquaporin (TIP2) Involved in Abiotic Stress Responses

Aquaporin has important role in various physiological processes in plants, including growth, development and adaptation to stress. In this context, aquaporin is reported to play relevant roles in plant tolerance to unfavorable drought conditions. In this study, the promoter region (950 kb) of a gene encoding a tonoplast intrinsic aquaporin (TIP2) from Eucalyptus grandis was cloned and functionally analyzed. Tissue-specificity and promoter responsiveness to abiotic stress was investigated using histochemical and relative quantification of GUS expression in stably transformed Nicotiana tabacum SR1 plants. Histochemical analyses of GUS activity revealed reporter expression mainly in the vasculature and in root tips of unstressed transgenic seedlings at different development stages (2, 3 and 4 leaves). Moreover, promoter activity was induced by osmotic stress at 3 and 24 hours after seedling exposure to mannitol. These results suggest that, under normal conditions, the investigated promoter drives a preferential expression in vascular tissues. We suggest yet, that the investigated aquaporin plays an important role in stress response.

Keywords: promoter; aquaporin; tissue-specificity; abiotic stress.

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