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Transcriptome and hormone profiling reveals Eucalyptus grandis defence responses against Chrysoporthe austroafricana.

ABSTRACT: Eucalyptus species and interspecific hybrids exhibit valuable growth and wood properties that make them a highly desirable commodity. However, these trees are challenged by a wide array of biotic stresses during their lifetimes. The Eucalyptus grandis reference genome sequence provides a resource to study pest and pathogen defence mechanisms in long-lived woody plants. E. grandis trees are generally susceptible to Chrysoporthe austroafricana, a causal agent of stem cankers on eucalypts. The aim of this study was to characterize the defence response of E. grandis against C. austroafricana.Hormone profiling of susceptible and moderately resistant clonal E. grandis genotypes indicated a reduction in salicylic acid and gibberellic acid levels at 3 days post inoculation. We hypothesized that these signaling pathways may facilitate resistance. To further investigate other defence mechanisms at this time point, transcriptome profiling was performed. This revealed that cell wall modifications and response to oxidative stress form part of the defence responses common to both genotypes, whilst changes in the hormone signaling pathways may contribute to resistance. Additionally the expression of selected candidate defence response genes was induced earlier in moderately resistant trees than in susceptible trees, supporting the hypothesis that a delayed defence response may occur in the susceptible interaction.The ability of a host to fine-tune its defence responses is crucial and the responses identified in this study extends our understanding of plant defence, gained from model systems, to woody perennials.

SUBMITTER: Mangwanda R

PROVIDER: S-EPMC4405875 | biostudies-other | 2015

REPOSITORIES: biostudies-other

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Transcriptome and hormone profiling reveals Eucalyptus grandis defence responses against Chrysoporthe austroafricana.

Mangwanda Ronishree R Myburg Alexander A AA Naidoo Sanushka S

BMC genomics 20150418

<h4>Background</h4>Eucalyptus species and interspecific hybrids exhibit valuable growth and wood properties that make them a highly desirable commodity. However, these trees are challenged by a wide array of biotic stresses during their lifetimes. The Eucalyptus grandis reference genome sequence provides a resource to study pest and pathogen defence mechanisms in long-lived woody plants. E. grandis trees are generally susceptible to Chrysoporthe austroafricana, a causal agent of stem cankers on ...[more]

PMID: 25903559

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Project description:BACKGROUND:Schizaphis graminum is one of the most important and devastating cereal aphids worldwide, and its feeding can cause chlorosis and necrosis in wheat. However, little information is available on the wheat defence responses triggered by S. graminum feeding at the molecular level. RESULTS:Here, we collected and analysed transcriptome sequencing data from leaf tissues of wheat infested with S. graminum at 2, 6, 12, 24 and 48?hpi (hours post infestation). A total of 44,835 genes were either up- or downregulated and differed significantly in response to aphid feeding. The expression levels of a number of genes (9761 genes) were significantly altered within 2 hpi and continued to change during the entire 48?h experiment. Gene Ontology analysis showed that the downregulated DEGs were mainly enriched in photosynthesis and light harvesting, and the total chlorophyll content in wheat leaves was also significantly reduced after S. graminum infestation at 24 and 48?hpi. However, a number of related genes of the salicylic acid (SA)-mediated defence signalling pathway and MAPK-WRKY pathway were significantly upregulated at early feeding time points (2 and 6 hpi). In addition, the gene expression and activity of antioxidant enzymes, such as peroxidase and superoxide dismutase, were rapidly increased at 2, 6 and 12 hpi. DAB staining results showed that S. graminum feeding induced hydrogen peroxide (H2O2) accumulation at the feeding sites at 2 hpi, and increased H2O2 production was detected with the increases in aphid feeding time. Pretreatment with diphenylene iodonium, an NADPH oxidase inhibitor, repressed the H2O2 accumulation and expression levels of SA-associated defence genes in wheat. CONCLUSIONS:Our transcriptomic analysis revealed that defence-related pathways and oxidative stress in wheat were rapidly induced within hours after the initiation of aphid feeding. Additionally, NADPH oxidase plays an important role in aphid-induced defence responses and H2O2 accumulation in wheat. These results provide valuable insight into the dynamic transcriptomic responses of wheat leaves to phytotoxic aphid feeding and the molecular mechanisms of aphid-plant interactions.

Dataset Information

Transcriptome and hormone profiling reveals Eucalyptus grandis defence responses against Chrysoporthe austroafricana.

Publications

Transcriptome and hormone profiling reveals Eucalyptus grandis defence responses against Chrysoporthe austroafricana.

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