02504nas a2200277   4500008004100000022001400041245014100055210006900196260002900265300001600294490000700310520159700317653002301914653002101937653002201958653003801980653003402018100001602052700001602068700001802084700001502102700001402117700002102131700001902152856005502171       2011                        eng d  a1365-305900aPhosphite primed defence responses and enhanced expression of defence genes in Arabidopsis thaliana infected with Phytophthora cinnamomi0 aPhosphite primed defence responses and enhanced expression of de  bBlackwell Publishing Ltd  a1086–10950 v603 a<p>This paper describes the effect of phosphite (Phi), a systemic chemical, on the induction of defence responses in <em>Phytophthora cinnamomi</em>-infected <em>Arabidopsis thaliana</em> accessions Ler and Col-0. Application of Phi to non-inoculated <em>A. thaliana</em> seedlings of accession Ler elevated transcription of defence genes in the salicylic acid (PR1 and PR5) and jasmonic acid/ethylene (THI2.1 and PDF1.2) pathways. Furthermore, a systemic increase in the expression of the PR1 gene was demonstrated in Phi-treated seedlings using the transgenic line PR1::GUS in the presence/absence of the pathogen by 72 h after inoculation. The cells of Phi-treated <em>A. thaliana</em> Ler leaves responded to <em>P. cinnamomi</em> zoospore inoculation with a rapid increase in callose deposition and hydrogen peroxide (H2O2) production. Phi treatment resulted in the production of callose papillae 6 h earlier than in non-Phi-treated inoculated seedlings and enhanced the production of H2O2 in the leaves of <em>A. thaliana</em> at the site of hyphal penetration and in cells away from the inoculation point. By 24 h after infection, clear differences in the amount of H2O2 production were observed between the Phi-treated and non-Phi-treated plants. These rapid host responses did not occur in non-Phi-treated inoculated seedlings. There was also a significant (P &lt; 0·001) decrease in lesion size in Phi-treated plants. These results indicate that Phi primes the plant for a rapid and intense response to infection involving heightened activation of a range of defence responses.</p>10acallose deposition10adefence response10ahydrogen peroxide10apotassium phosphonate (phosphite)10areactive oxygen species (ROS)1 aEshraghi, L1 aAnderson, J1 aAryamanesh, N1 aShearer, B1 aMcComb, J1 aHardy, StJ., G E1 aO’Brien, P A  uhttp://dx.doi.org/10.1111/j.1365-3059.2011.02471.x