A pathogen‐inducible patatin‐like lipid acyl hydrolase facilitates fungal and bacterial host colonization in Arabidopsis

Abstract

SummaryGenes and proteins related to patatin, the major storage protein of potato tubers, have been identified in many plant species and shown to be induced by a variety of environmental stresses. The Arabidopsis patatin-like gene family (PLPs) comprises nine members, two of which (PLP2 and PLP7) are strongly induced in leaves challenged with fungal and bacterial pathogens. Here we show that accumulation of PLP2 protein in response to Botrytis cinerea or Pseudomonas syringae pv. tomato (avrRpt2) is dependent on jasmonic acid and ethylene signaling, but is not dependent on salicylic acid. Expression of a PLP2-green fluorescent protein (GFP) fusion protein and analysis of recombinant PLP2 indicates that PLP2 encodes a cytoplasmic lipid acyl hydrolase with wide substrate specificity. Transgenic plants with altered levels of PLP2 protein were generated and assayed for pathogen resistance. Plants silenced for PLP2 expression displayed enhanced resistance to B. cinerea, whereas plants overexpressing PLP2 were much more sensitive to this necrotrophic fungus. We also established a positive correlation between the level of PLP2 expression in transgenic plants and cell death or damage in response to paraquat treatment or infection by avirulent P. syringae. Interestingly, repression of PLP2 expression increased resistance to avirulent bacteria, while PLP2-overexpressing plants multiplied avirulent bacteria close to the titers reached by virulent bacteria. Collectively, the data indicate that PLP2-encoded lipolytic activity can be exploited by pathogens with different lifestyles to facilitate host colonization. In particular PLP2 potentiates plant cell death inflicted by Botrytis and reduces the efficiency of the hypersensitive response in restricting the multiplication of avirulent bacteria. Both effects are possibly mediated by providing fatty acid precursors of bioactive oxylipins.

The WRKY70 transcription factor of Arabidopsis influences both the plant senescence and defense signaling pathways

“…In contrast, loss-ofAtWRKY70 function resulted in enhanced susceptibility to E. cichoracearum and B. cinerea (AbuQamar et al 2006). Moreover, recent studies showed that necrotrophs deliberately trigger HR in the host, which subsequently leads to cell death and necrosis and hence might be a strategy used by these pathogens to initiate colonization of host tissue (Govrin and Levine 2000;La Camera et al 2005). The fact that AtWRKY70 expression is regulated both by defense-and senescence-associated signals acting in a coordinated manner indicates that AtWRKY70 function may be required to integrate signals that link both pathways.…”

SOBER1 phospholipase activity suppresses phosphatidic acid accumulation and plant immunity in response to bacterial effector AvrBsT

“…The majority of theses proteins are patatinrelated plant PLAs (34)(35)(36)(37). Interestingly, AtPLP2 is a plant susceptibility factor during fungal and bacterial infection (37). By contrast, other PLA 2 s promote cell death associated with defense and development (34)(35)(36)38).…”

“…A number of PLA 2 enzymes have been linked to plant defense signaling (33). The majority of theses proteins are patatinrelated plant PLAs (34)(35)(36)(37). Interestingly, AtPLP2 is a plant susceptibility factor during fungal and bacterial infection (37).…”

Quantitative Proteomics Reveals Dynamic Changes in the Plasma Membrane During Arabidopsis Immune Signaling

“…Additionally, proteins with phospholipase A 2 activity (PLP2a/pPLA-II␣ and SOBER1) increased significantly in PM fractions during ETI. PLP2a/pPLA-II␣ has diverse lipid substrates in vitro and has been shown to accumulate during ETI and positively regulate cell death (41). In contrast, SOBER1 activity suppresses phosphatidic acid accumulation during ETI and represses HR in response to the effector AvrBsT (63).…”