A quest for long-distance signals: the epidermis as central regulator of pipecolic acid-associated systemic acquired resistance.

The role of ALD1 in systemic acquired resistance (SAR) SAR is a form of induced resistance that is activated in systemic, healthy tissues of plants undergoing a localized infection (Vlot et al., 2020). Therefore, it is striking that accumulation of ALD1 in the chloroplasts of epidermal cells suffices for a full complementation of the defense- and SAR-compromised phenotypes of ald1 mutant plants (Jiang et al., 2021). Jiang et al. (2021) exploited the conditional expression of an ALD1 transgene from a dexamethasone (DEX)-inducible promoter to study the role of ALD1 in disease resistance and SAR. [Extracted from the article]