A phosphatidic acid-based retrograde signaling pathway responsive to abiotic stress in Arabidopsis.

In the long term, stress experienced by the chloroplast must be communicated to the nucleus to adjust the expression of genes providing robust abiotic stress resilience in a process called retrograde signaling.

We propose a retrograde signaling mechanism that starts with the accumulation of phosphatidic acid at the outer chloroplast membrane. A mutant of Arabidopsis thaliana, lppγ lppɛ1, disrupted in two chloroplast envelope membrane-located phosphatidic acid phosphatases shows reduced growth and activation of abscisic acid-mediated abiotic stress response pathways, among other changes, as determined by RNA-Seq analysis. The mutant is more resistant to freezing and osmotic stress.