Induction of wound response genes in tomato leaves by bestatin, an inhibitor of aminopeptidases.

Abstract

Bestatin, an inhibitor of some aminopeptidases in plants and animals, is a powerful inducer of defense genes in tomato leaves; these genes are also induced by herbivore attacks, mechanical wounding, systemin, and methyl jasmonate. Unlike wounding and systemin, bestatin does not cause an increase in intracellular jasmonic acid concentrations, and inhibitors of the octadecanoid pathway do not inhibit induction by bestatin. Furthermore, defense genes were induced by bestatin in a mutant tomato line (JL-5) with a defect in the octadecanoid pathway. Bestatin therefore appears to be exerting its effects close to the level of transcriptional control of these genes, where it may be inhibiting a regulatory protease.

A Gene Encoding a Chloroplast-Targeted Lipoxygenase in Tomato Leaves Is Transiently Induced by Wounding, Systemin, and Methyl Jasmonate

“…plants by chewing insects or other mechanical means results in the rapid transcriptional activation of defense genes, both in the wounded leaf and in distant, unwounded leaves (Graham et al, 1986;Hildmann et al, 1992;Schaller et al, 1995). A phloem mobile polypeptide called systemin behaves as a systemic signal released from wound sites (Pearce et al, 1991;McGurl et al, 1992McGurl et al, , 1994Narvaez-Vasquez et al, 1995), but severa1 other chemicals, including IAA (Thornburg and Li, 1990), ABA (PeAa-Cortés et al, 1989), and ethylene (ODonnell et al, 1996), have been associated with the signaling pathway and with physical forces such as hydraulic effects (Malone and Alarcon, 1995) and action potentials (Herde et al, 1996;Rhodes et al, 1996;Stankovic and Davies, 1996).…”

“…The LOX 19 amino acid sequence exhibited 81% identity to the fruit-specific TomLOXA (Ferrie et al, 1994) and was not studied further. On the basis of sequence similarities with plant LOX sequences (see below), the Lox 6 and Lox 18 clones were chosen as probes to screen a cDNA library constructed from plants overexpressing a prosystemin transgene and overexpressing severa1 defense genes (McGurl et al, 1994;Schaller et al, 1995). We isolated full-length clones of 2807 and 3034 bp corresponding to Lox 6 and Lox 18, respectively, and these clones were called TomLoxC and TomLoxD, respectively.…”

Bestatin, an Inhibitor of Aminopeptidases, Provides a Chemical Genetics Approach to Dissect Jasmonate Signaling in Arabidopsis

“…It was previously reported that bestatin is a powerful inducer of tomato defense genes, which also are induced by herbivore attack, mechanical wounding, and the potent wound-response elicitors, such as systemin and JA (Schaller et al, 1995). Given that JA works as a systemic wound signal and plays a central role in regulating defense genes expression in response to herbivore attack and mechanical wounding, we further compared the action mode of bestatin with that of JA in tomato and Arabidopsis, two of the most extensively studied systems on JA and wound signaling.…”

“…The tomato wound-response mutants spr2 (Li et al, 2003) and jai1-1 (Li et al, 2004) were in the genetic background of cv Castlemart. Tomato plants were grown at standard conditions as described previously (Schaller et al, 1995;Li et al, 2003). Eighteen to 20 d after planting, plants were excised at the base of the stem and placed in 0.5-mL microfuge tubes containing 300 mL of the inducing compound for 2 h. Plants were then transferred to glass vials containing 20 mL of water and incubated in a Lucite box for 24 h under continuous light.…”

“…Bestatin, a potent inhibitor of some aminopeptidases in plants and animals, was shown previously to be a powerful inducer of wound-response genes in tomato (Schaller et al, 1995). Bestatin has been widely used as an experimental tool in elucidating the physiological role of some mammalian exopeptidases in the regulation of the immune system, in the growth of tumors, and in the degradation of cellular proteins (Scornik and Botbol, 2001).…”