02254nas a2200253 4500008004100000022001400041245011100055210006900166260002900235300001400264490000700278520146500285653002101750653001401771653002701785653002301812653001901835653002301854100001601877700001501893700001801908700001901926856005501945 2012 eng d a1365-305900aAlteration of physiological parameters of Austrocedrus chilensis by the pathogen Phytophthora austrocedrae0 aAlteration of physiological parameters of Austrocedrus chilensis bBlackwell Publishing Ltd a877–8880 v613 a

The effect of the pathogen Phytophthora austrocedrae on tree physiology of Austrocedrus chilensis in Patagonia was studied in a 4-week study. In the first week, stem-inoculated saplings showed a significant decrease in photosynthesis (A) without alteration of stomatal conductance (gs) or stem-specific hydraulic conductivity (Ks). From the second week on, progressive decreases in A, gs and Ks were observed, concomitantly with development of significant stem lesions. Water use efficiency (WUE) increased in the second week and declined progressively from the third week. Hyphae and resinous materials were observed in tracheids and rays below lesions. Necrosis of parenchyma ray cells and blockage of tracheids torus were observed. Healthy xylem showed no resinous materials or tracheid blockage, but abundant starch in rays, which was absent in altered xylem. The culture filtrate (CF) of the pathogen was shown to induce changes in extracellular pH and conductivity, and increased necrosis in tissues of leaves and stem challenged with CF in vitro. Similar results were obtained in leaf tissues of the inoculated saplings in vivo. CF injection into xylem of saplings induced a decline in A and disturbance of leaf tissue integrity, without altering gs, WUE or Ks. The decrease of A correlated with changes in tissue integrity. A possible mechanism of A. chilensis decline induced by P. austrocedrae is discussed.

10acypress root rot10aeffectors10ahydraulic conductivity10amal del cipr√©s10aphotosynthesis10axylem colonization1 aVélez, M L1 aSilva, P V1 aTroncoso, O A1 aGreslebin, A G uhttp://dx.doi.org/10.1111/j.1365-3059.2011.02585.x