Transgenic Arabidopsis and tobacco plants overexpressing an aquaporin respond differently to various abiotic stresses

Abstract

Despite the high isoform multiplicity of aquaporins in plants, with 35 homologues including 13 plasma membrane intrinsic proteins (PIPs) in Arabidosis thaliana, the individual and integrated functions of aquaporins under various physiological conditions remain unclear. To better understand aquaporin functions in plants under various stress conditions, we examined transgenic Arabidopsis and tobacco plants that constitutively overexpress Arabidopsis PIP1;4 or PIP2;5 under various abiotic stress conditions. No significant differences in growth rates and water transport were found between the transgenic and wild-type plants when grown under favorable growth conditions. The transgenic plants overexpressing PIP1;4 or PIP2;5 displayed a rapid water loss under dehydration stress, which resulted in retarded germination and seedling growth under drought stress. In contrast, the transgenic plants overexpressing PIP1;4 or PIP2;5 showed enhanced water flow and facilitated germination under cold stress. The expression of several PIPs was noticeably affected by the overexpression of PIP1;4 or PIP2;5 in Arabidopsis under dehydration stress, suggesting that the expression of one aquaporin isoform influences the expression levels of other aquaporins under stress conditions. Taken together, our results demonstrate that overexpression of an aquaporin affects the expression of endogenous aquaporin genes and thereby impacts on seed germination, seedling growth, and stress responses of the plants under various stress conditions.

Overexpression of PIP2;5 Aquaporin Alleviates Effects of Low Root Temperature on Cell Hydraulic Conductivity and Growth in Arabidopsis

“…In this study, we used genetically transformed Arabidopsis plants overexpressing PIP1;4 and PIP2;5 (Jang et al, 2007) to examine the role of these aquaporins in the responses of plants to low root temperature. The PIP1;4 and PIP2;5 aquaporins were chosen because of the reported increase in their expression levels in roots of plants exposed to low air temperature (Jang et al, 2004).…”

Ocimum sanctum leaf extract induces drought stress tolerance in rice

“…Transgenic tobacco and Arabidopsis plants over-expressing PIP1;4 or PIP2;5 showed rapid water loss under dehydration stress and it was speculated that enhanced water transport via the plasma membranes of cells may be deleterious under water stress. 43 Constitutive over-expression of an AQP gene GoPIP1 from G. orientalis in Arabidopsis led to decreased drought resistance and enhanced drought sensitivity in transgenic Arabidopsis. The transgenic plants over-expressing GoPIP1 had lower leaf water content and lower water potential and had faster water loss through leaves to the atmosphere, indicating that GoPIP1 might affect stomatal aperture thus modifying water movement.…”

Heat stress-mediated gene expression in the body wall of the Japanese sea cucumber Apostichopus japonicus

“…The amount of zinc finger protein in cells appears to be small under favorable conditions; however, transcription is increased and this protein is among the STREs when unfavorable conditions are encountered. Therefore, STRE-dependent transcriptional induction normally occurs rapidly (Kim et al 2005, Jang et al 2007). In the present study, expression of the gene coding for the zinc finger protein increased 2-fold after heat stress and this increase, together with the enhancement of some regulated factors, strengthened the defense of the organism and reduced the damage to cell function.…”