Abstract
The abscission of floral organs and emergence of lateral roots in Arabidopsis is regulated by the peptide ligand INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) and the receptor protein kinases HAESA (HAE) and HAESA-LIKE 2 (HSL2). During these cell separation processes, the plant induces defense-associated genes to protect against pathogen invasion. However, the molecular coordination between abscission and immunity has not been thoroughly explored. Here we show that IDA induces a receptor-dependent release of cytosolic calcium ions (Ca2+) and apoplastic production of reactive oxygen species, which are signatures of early defense responses. In addition, we find that IDA promotes late defense responses by the transcriptional upregulation of genes known to be involved in immunity. When comparing the IDA induced early immune responses to known immune responses, such as those elicited by flagellin22 treatment, we observe both similarities and differences. We propose a molecular mechanism by which IDA promotes signatures of an immune response in cells destined for separation to guard them from pathogen attack.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
This version contains substantially additional results and revision of the manuscript. This version contains additional results mIDA induced elevation of cytosolic Ca2+ responses in other tissue, such as in the abscission zone. In addition this version contains additional results showing that IDA is involved in regulating a flg22 induced transcriptional response. The results in version 1 showing an interaction between HSL2 and RLK7 is taken out of the version 2 to focus the story on the role of IDA in regulating molecular responses involved in defense, and comparing these responses to other known immune signaling responses. The author list has been changed based on results taken out from the version 1 and additional results added to version 2. The final figure has been updated to fit the new results.
