BioProject

Transgenic Arabidopsis plants with constitutively low inositol (1,4,5) triphosphate exhibit an increased tolerance to water stress by an ABA-independent pathway The phosphoinositide pathway and inositol (1,4,5) trisphopsphate (InsP3) are implicated in plant responses to stress. More...

Transgenic Arabidopsis plants with constitutively low inositol (1,4,5) triphosphate exhibit an increased tolerance to water stress by an ABA-independent pathway The phosphoinositide pathway and inositol (1,4,5) trisphopsphate (InsP3) are implicated in plant responses to stress. In order to manipulate the pathway and determine the downstream consequences of altered InsP3-mediated signaling, we generated transgenic Arabidopsis plants expressing the mammalian type I inositol polyphosphate 5-phosphatase, an enzyme that specifically hydrolyzes the soluble inositol phosphates and terminates the signal. Transgenic plants have no morphological differences compared to wild type; however, rapid transient Ca2+ responses to a cold or salt stimulus are reduced by ~ 30%. To further understand the role of InsP3-mediated signaling in plant stress responses we focused on drought stress. Surprisingly, the InsP 5-ptase plants lose less water and exhibited an increased tolerance to drought. Stomatal bioassays showed that transgenic guard cells are less responsive to the inhibition of opening by ABA but show an increased sensitivity to ABA-induced closure. The onset of the drought stress is delayed in the transgenic plants and ABA levels did not increase as much as in the wild type. Transcript profiling has revealed that DREB2A and a subset of DREB2A regulated genes are basally up regulated in the InsP 5-ptase plants. These results indicate that the drought tolerance of the InsP 5-ptase plants is mediated in part via an ABA-independent pathway. The constitutive dampening of the InsP3 signal in this system has uncovered novel regulation and cross talk between signaling pathways. Keywords: drought stress, expression study Overall design: In order to compare global expression profiles between wild type and transgenic plants in response to water stress we harvested leaves for transcript profiling at day 0 (well watered) and at day 7 when the transgenic plants were still at an RWC of >85% and the wild type and vector control plants were at an RWC of ~ 50 -60% . Leaves were harvested and pooled from ~ 10 plants of each line/time point and three independent biological replicates were carried out with wild type (WT) and 2 independent transgenic lines (T6 and T8). The vector control line (C2) was used as an additional control. Less...