Jasmonate‐dependent modifications of the pectin matrix during potato development function as a defense mechanism targeted by D ickeya dadantii virulence factors

• Published in: The Plant journal : for cell and molecular biology 2014-02, Vol.77 (3), p.418-429
• Main Authors: Taurino, Marco, Abelenda, Jose A., Río‐Alvarez, Isabel, Navarro, Cristina, Vicedo, Begonya, Farmaki, Theodora, Jiménez, Pedro, García‐Agustín, Pilar, López‐Solanilla, Emilia, Prat, Salomé, Rojo, Enrique, Sánchez‐Serrano, José J., Sanmartín, Maite
• Format: Article
• Language: English
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.12393

The plant cell wall constitutes an essential protection barrier against pathogen attack. In addition, cell‐wall disruption leads to accumulation of jasmonates ( JA s), which are key signaling molecules for activation of plant inducible defense responses. However, whether JA s in return modulate the cell‐wall composition to reinforce this defensive barrier remains unknown. The enzyme 13–allene oxide synthase (13– AOS ) catalyzes the first committed step towards biosynthesis of JA s. In potato ( S olanum tuberosum ), there are two putative St13– AOS genes, which we show here to be differentially induced upon wounding. We also determine that both genes complement an Arabidopsis aos null mutant, indicating that they encode functional 13– AOS enzymes. Indeed, transgenic potato plants lacking both St13– AOS genes ( Co AOS 1 / 2 lines) exhibited a significant reduction of JA s, a concomitant decrease in wound‐responsive gene activation, and an increased severity of soft rot disease symptoms caused by Dickeya dadantii . Intriguingly, a hypovirulent D . dadantii pel strain lacking the five major pectate lyases, which causes limited tissue maceration on wild‐type plants, regained infectivity in Co AOS 1 / 2 plants. In line with this, we found differences in pectin methyl esterase activity and cell‐wall pectin composition between wild‐type and C o AOS 1 / 2 plants. Importantly, wild‐type plants had pectins with a lower degree of methyl esterification, which are the substrates of the pectate lyases mutated in the pel strain. These results suggest that, during development of potato plants, JA s mediate modification of the pectin matrix to form a defensive barrier that is counteracted by pectinolytic virulence factors from D. dadantii .