Abstract
Wounding due to mechanical injury or insect feeding causes a wide array of damage to plant cells including cell disruption, desiccation, metabolite oxidation, and disruption of primary metabolism. In response, plants regulate a variety of genes and metabolic pathways to cope with injury. Tomato (Solanum lycopersicum) is a model for wound signaling but few studies have examined the comprehensive gene expression profiles in response to injury. A cross-species microarray approach using the TIGR potato 10-K cDNA array was analyzed for large-scale temporal (early and late) and spatial (locally and systemically) responses to mechanical wounding in tomato leaves. These analyses demonstrated that tomato regulates many primary and secondary metabolic pathways and this regulation is dependent on both timing and location. To determine if LAP-A, a known modulator of wound signaling, influences gene expression beyond the core of late wound-response genes, changes in RNAs from healthy and wounded Leucine aminopeptidase A-silenced (LapA-SI) and wild-type (WT) leaves were examined. While most of the changes in gene expression after wounding in LapA-SI leaves were similar to WT, overall responses were delayed in the LapA-SI leaves. Moreover, two pathogenesis-related 1 (PR-1c and PR-1a2) and two dehydrin (TAS14 and Dhn3) genes were negatively regulated by LAP-A. Collectively, this study has shown that tomato wound responses are complex and that LAP-A’s role in modulation of wound responses extends beyond the well described late-wound gene core.
Highlights
In nature, plants must cope with a multitude of stresses individually and simultaneously
In order to identify transcriptome changes that occurred after injury in tomato, a cross-species hybridization (CSH) cDNA microarray study was used to assess RNA levels in wounded and apical, non-wounded leaves from WT plants at 0, 1 and 8 hr after wounding
48% of the genes that responded at 1 hr (158 Differentially expressed genes (DEGs)) were transiently expressed, with their RNA levels returning to pre-damage levels by 8 hr (Figure 1)
Summary
Plants must cope with a multitude of stresses individually and simultaneously. Many of the abiotic (rain, hail, wind) and biotic stresses (herbivory) breach cellular integrity causing membrane disruption, desiccation, lipid and protein oxidation, and protein aggregation [1]. This damage can range from mild (responses to phloem-feeding whiteflies, psyllids and aphids) to extreme (responses to pruning, hail or herbivores that chew and tear plant tissues) [2]. At the core of the wound response are the defenses activated by oxylipins, including jasmonic acid (JA) and its bioactive isoleucine conjugate JA-Ile [6]. The woundresponse pathway involves the integration of a complex and dynamic defense-signaling network that involves JA, salicylic acid (SA), abscisic acid (ABA), ethylene (ET), gibberellic acid (GA), brassinosteroids, cytokinins, as well as reactive oxygen species (ROS) and redox changes [12]
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