Transcriptome Analysis of Quantitative Resistance-Specific Response upon Ralstonia solanacearum Infection in Tomato

Abstract

Bacterial wilt, caused by the soil-borne bacterium Ralstonia solanacearum, is a lethal disease of tomato, but the molecular mechanisms of the host resistance responses to R. solanacearum remain unclear. In this study, we report the first work describing the transcriptome of cultivar resistance and susceptible tomato cultivar after inoculation with R. solanacearum. To elucidate the characteristics of resistance early in the interaction, we analyzed microarrays for resistant cultivar LS-89 and susceptible cultivar Ponderosa 1 day after stem inoculation. No change in gene expression was detected for Ponderosa, but expression levels of over 140 genes, including pathogenesis-related, hormone signaling and lignin biosynthesis genes, increased in LS-89. Expression of β-1,3-glucanase genes increased substantially. In an immunohistochemical study, glucanase in LS-89 accumulated in the xylem and pith tissues surrounding xylem vessels filled with R. solanacearum. The expression of these genes also increased in four other resistant cultivars, but changed little in four susceptible cultivars in response to R. solanacearum, suggesting that similar reactions occur in other cultivars. These gene expression profiles will serve as fundamental information to elucidate the molecular mechanisms in the resistance response to R. solanacearum in tomato.

Hydroxycinnamic Acid Degradation, a Broadly Conserved Trait, ProtectsRalstonia solanacearumfrom Chemical Plant Defenses and Contributes to Root Colonization and Virulence

“…4C). Because R. solanacearum infections induce expression of tomato phenolic biosynthesis genes (Ishihara et al, 2012; Mitra, Milling, and Allen unpublished), we hypothesized that xylem sap from infected plants contains higher HCA concentrations that would benefit growth of the WT strain. However, we detected no differences in growth between WT and Δ fcs when they were grown in sap harvested from plants infected with WT or the Δ fcs mutant (data not shown).…”

“…LS-89, but not in susceptible tomato cv. Ponderosa (Ishihara et al, 2012). Histopathological studies of resistant and susceptible tomato found that R. solanacearum colonized fewer xylem vessels in wilt-resistant varieties (Grimault et al, 1994; Rahman et al, 1999).…”

“…Quantitative resistance of tomato cultivars against R. solanacearum is correlated with early expression of phenylalanine ammonia lyase (PAL), which catalyzes the first step in phenylpropanoid biosynthesis (Vanitha et al, 2009). Transcriptomic analysis showed that multiple phenylpropanoid biosynthesis genes are upregulated in R. solanacearum -infected, resistant tomato plants compared to healthy plants (Ishihara et al, 2012) (Milling and Allen, unpublished). We previously found that drug efflux pumps protect R. solanacearum from the toxicity of many plant defense chemicals, including the HCA caffeate (Brown et al, 2007).…”

Resistance against Ralstonia solanacearum in tomato depends on the methionine cycle and the γ‐aminobutyric acid metabolic pathway

“…Major sources of bacterial wilt resistance in tomato originate from Solanum pimpinellifolium and S. lycopersicum var. cerasiforme (Ishihara et al ., ). ‘Hawaii 7996’ has been shown to have stable resistance against several R. solanacearum strains (Upreti and Thomas, ).…”

Magnesium oxide nanoparticles induce systemic resistance in tomato against bacterial wilt disease

“…Although information on the mechanisms underlying defence responses against R. solanacearum is still limited, several reports have indicated that SA, JA and ET signalling are involved in resistance responses in tomato. A transcriptome analysis showed that expression of genes for JA/ET biosynthesis is increased in the resistant tomato cultivar LS‐89 in response to R. solanacearum infection (Ishihara et al ., ). Chen et al .…”