Arabidopsis Annexins AnnAt1 and AnnAt4 Interact with Each Other and Regulate Drought and Salt Stress Responses

Abstract

Annexins are Ca2+--and phospholipid-binding proteins that form an evolutionarily conserved multigene family throughout the animal and plant kingdoms. Two annexins, AnnAt1 and AnnAt4, have been identified as components in osmotic stress and abscisic acid signaling in Arabidopsis. Here, we report that AnnAt1 and AnnAt4 regulate plant stress responses in a light-dependent manner. The single-mutant annAt1 and annAt4 plants showed tolerance to drought and salt stress, which was greatly enhanced in double-mutant annAt1annAt4 plants, but AnnAt4-overexpressing transgenic plants (35S:AnnAt4) were more sensitive to stress treatments under long day conditions. Furthermore, expression of stress-related genes was altered in these mutant and transgenic plants. Upon dehydration and salt treatment, AtNCED3, encoding 9-cis-epoxycarotenoid dioxygenase, and P5CS1, encoding Δ-1-pyrroline-5-carboxylate synthase, which are key enzymes in ABA and proline synthesis, respectively, were highly induced in annAt1annAt4 plants and to a lesser extent in annAt1 and annAt4 plants, but not in 35S:AnnAt4 plants. While annAt1 plants were more drought sensitive, annAt4 plants were more tolerant in short days than in long days. In vitro and in vivo binding assays revealed that AnnAt1 and AnnAt4 bind to each other in a Ca2+-dependent manner. Our results suggest that AnnAt1 and AnnAt4 function cooperatively in response to drought and salt stress and their functions are affected by photoperiod.

Salinity-Induced Calcium Signaling and Root Adaptation in Arabidopsis Require the Calcium Regulatory Protein Annexin1

“…Previously, AtANN1 was found to be important for drought tolerance (Konopka-Postupolska et al, 2009;Huh et al, 2010) and germination under salinity stress (Lee et al, 2004). This study has revealed AtANN1 to be a significant component of [Ca 2+ ] cyt signaling and adaptive root growth under salinity stress.…”

Illumination of Arabidopsis roots induces immediate burst of ROS production

“…In addition, it was observed that expression level of certain protein, such as annexin AnnAt4, is altered dramatically in soil-grown instead of light-grown Arabidopsis roots grown in transparent Petri dishes. 15 Besides visible light, roots are very sensitive also to UV-B light with root apex being the most sensitive part of plant roots. [16][17][18][19] Recent study has reported that UVR8 protein is the UV-B receptor both in roots and shoots.…”

Arabidopsis Annexin1 Mediates the Radical-Activated Plasma Membrane Ca2+- and K+-Permeable Conductance in Root Cells

“…Additionally, the question now arises of whether annexins function as Ca 2+ influx transporters in other tip-growing cells in which growth is linked to NADPH oxidase activity, such as pollen tubes and fungal hyphae (CanoDomínguez et al, 2008;Liu et al, 2009). Ca 2+ influx mediated by ANN1 may also help explain the drought and salt sensitivity of the ann1 mutant (KonopkaPostupolska et al, 2009;Huh et al, 2010), particularly as plant …”