Abstract

Plants are constantly challenged by numerous, sometimes simultaneous stresses. One important stress, salinity, is a growing problem for various countries and can influence plant growth and productivity. Plant response to salt stress has been well documented; initial events include an increase in root cytosolic free calcium ([Ca2+]cyt), the production of reactive oxygen species (ROS) and membrane peroxidation. These events are crucial for activating downstream responses such as gene transcription and long-term salt stress responses. The sensors for sodium and the channel proteins mediating the [Ca2+]cyt increase are unknown. Plant annexins are multi-gene, multifunctional proteins which are capable of Ca2+-dependent membrane binding. We have shown previously that maize annexins can form novel Ca2+-permeable channels (Plant Cell 21, 479) and are now testing whether Arabidopsis annexins are involved in salt stress signalling, acting as Ca2+ channels.