Allene oxide cyclase dependence of the wound response and vascular bundle‐specific generation of jasmonates in tomato – amplification in wound signalling

Abstract

zThe first two authors contributed equally to this work. SummaryThe allene oxide cyclase (AOC)-catalyzed step in jasmonate (JA) biosynthesis is important in the wound response of tomato. As shown by treatments with systemin and its inactive analog, and by analysis of 35S::prosysteminsense and 35S::prosysteminantisense plants, the AOC seems to be activated by systemin (and JA) leading to elevated formation of JA. Data are presented on the local wound response following activation of AOC and generation of JA, both in vascular bundles. The tissue-specific occurrence of AOC protein and generation of JA is kept upon wounding or other stresses, but is compromised in 35S::AOCsense plants, whereas 35S::AOCantisense plants exhibited residual AOC expression, a less than 10% rise in JA, and no detectable expression of wound response genes. The (i) activation of systemin-dependent AOC and JA biosynthesis occurring only upon substrate generation, (ii) the tissue-specific occurrence of AOC in vascular bundles, where the prosystemin gene is expressed, and (iii) the tissue-specific generation of JA suggest an amplification in the wound response of tomato leaves allowing local and rapid defense responses.

Role of cis-12-Oxo-Phytodienoic Acid in Tomato Embryo Development

“…There is a close correlation between AOC promoter activity, AOC protein accumulation, and JA levels in different developmental stages of tomato and in response to various environmental stimuli Stenzel et al, 2003Stenzel et al, , 2008. Similarly, AOC promoter activity and AOC protein accumulation closely correlated from heart stage of embryo development onwards (Fig.…”

“…An up-regulation and down-regulation, respectively, of the SlAOC transcript was found in leaves (Stenzel et al, 2003). The SlAOC protein level was not diminished in ovules of antisense lines compared to wildtype ovules (Miersch et al, 2004).…”

“…All materials (about 50-500 mg fresh weight) were immediately frozen in liquid nitrogen. Extraction, purification, and quantification of OPDA, dinor-OPDA, JA, 11-OH-JA, and 12-OH-JA were performed as described (Stenzel et al, 2003;Miersch et al, 2008).…”

“…Transgenic tomato cv MicroTom were generated by Agrobacteriummediated gene transfer essentially as described for generation of SlAOC::GUS lines . Analyses of integration numbers by Southern blot, level of SlAOC mRNA and protein were performed using primary transformants and T1 lines as described previously (Stenzel et al, 2003.…”

“…This allows JA formation within less than 5 min upon any stimulus that finally results in expression of JA biosynthesis genes and other JAresponsive genes (Glauser et al, 2009;). The regulation of JA biosynthesis by substrate availability and by a positive feedback loop is well described by different assays including transgenic approaches (Laudert et al, 2000;Stenzel et al, 2003).…”