678 / 2019-04-30 19:26:23

LEGUME LECTIN-LIKE PROTEINS at the interface of systemic immunity and salinity tolerance

Systemic Acquired Resistance,Salinity Tolerance,Salicylic Acid,Plant Immunity

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Systemic Acquired Resistance (SAR) is a broad spectrum induced defence response against biotrophic pathogens following a local infection. LEGUME LECTIN-LIKE PROTEIN 1 (LLP1) is required in systemic tissue for a successful SAR response to occur. LLP1 shares a high sequence homology with two other proteins, LLP2 and LLP3, which have not yet been studied with respect to systemic defence. Here, we present RNAi lines in which the transcript accumulation of LLP1, LLP2, and LLP3 is reduced, to explore possible functions of the encoded proteins. Although local defence responses remain unchanged, the transgenic lines show increased susceptibility to Pseudomonas syringae in their systemic tissue, suggesting that two or more LLPs act in concert during SAR. Additionally, as the individual LLPs show different responses to treatment with salicylic acid, jasmonic acid and abscisic acid, we investigated their role in the different associated defence pathways. We show that a reduction in LLP transcripts results in increased susceptibility to both high salinity and necrotrophic pathogens. The requirement of these proteins in multiple phytohormone pathways suggests a broader function in plant defence responses than previously identified.