ANNEXIN1 mediates calcium‐dependent systemic defense in Arabidopsis plants upon herbivory and wounding

Abstract

Cellular calcium (Ca) transients are endogenous signals involved in local and systemic sig- naling and defense activation upon environmental stress, including wounding and herbivory. Still, not all Ca 2+ channels contributing to the signaling have been identified, nor are their modes of action fully known. Plant annexins are proteins capable of binding to anionic phos- pholipids and can exhibit Ca channel-like activity. Arabidopsis ANNEXIN1 (ANN1) is sug- gested to contribute to Ca transport. � Here, we report that wounding and simulated-herbivory-induced cytosolic free Ca eleva- tion was impaired in systemic leaves in ann1 loss-of-function plants. We provide evidence for a role of ANN1 in local and systemic defense of plants attacked by herbivorous Spodoptera littoralis larvae. � Bioassays identified ANN1 as a positive defense regulator. Spodoptera littoralis feeding on ann1 gained significantly more weight than larvae feeding on wild-type, whereas those feed- ing on ANN1-overexpressing lines gained less weight. Herbivory and wounding both induced defense-related responses on treated leaves, such as jasmonate accumulation and defense gene expression. These responses remained local and were strongly reduced in systemic leaves in ann1 plants. � Our results indicate that ANN1 plays an important role in activation of systemic rather than local defense in plants attacked by herbivorous insects.