Dataset Information

Ralstonia solanacearum elicitor RipX Induces Defense Reaction by Suppressing the Mitochondrial atpA Gene in Host Plant.

ABSTRACT: RipX of Ralstonia solanacearum is translocated into host cells by a type III secretion system and acts as a harpin-like protein to induce a hypersensitive response in tobacco plants. The molecular events in association with RipX-induced signaling transduction have not been fully elucidated. This work reports that transient expression of RipX induced a yellowing phenotype in Nicotiana benthamiana, coupled with activation of the defense reaction. Using yeast two-hybrid and split-luciferase complementation assays, mitochondrial ATP synthase F1 subunit ? (ATPA) was identified as an interaction partner of RipX from N. benthamiana. Although a certain proportion was found in mitochondria, the YFP-ATPA fusion was able to localize to the cell membrane, cytoplasm, and nucleus. RFP-RipX fusion was found from the cell membrane and cytoplasm. Moreover, ATPA interacted with RipX at both the cell membrane and cytoplasm in vivo. Silencing of the atpA gene had no effect on the appearance of yellowing phenotype induced by RipX. However, the silenced plants improved the resistance to R. solanacearum. Moreover, qRT-PCR and promoter GUS fusion experiments revealed that the transcript levels of atpA were evidently reduced in response to expression of RipX. These data demonstrated that RipX exerts a suppressive effect on the transcription of atpA gene, to induce defense reaction in N. benthamiana.

SUBMITTER: Sun T

PROVIDER: S-EPMC7139787 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Ralstonia solanacearum elicitor RipX Induces Defense Reaction by Suppressing the Mitochondrial atpA Gene in Host Plant.

Sun Tingyan T Wu Wei W Wu Haoxiang H Rou Wei W Zhou Yinghui Y Zhuo Tao T Fan Xiaojing X Hu Xun X Zou Huasong H

International journal of molecular sciences 20200315 6

RipX of Ralstonia solanacearum is translocated into host cells by a type III secretion system and acts as a harpin-like protein to induce a hypersensitive response in tobacco plants. The molecular events in association with RipX-induced signaling transduction have not been fully elucidated. This work reports that transient expression of RipX induced a yellowing phenotype in Nicotiana benthamiana, coupled with activation of the defense reaction. Using yeast two-hybrid and split-luci ...[more]

PMID: 32183439

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Project description:UnlabelledPlants use the signaling molecule salicylic acid (SA) to trigger defenses against diverse pathogens, including the bacterial wilt pathogen Ralstonia solanacearum SA can also inhibit microbial growth. Most sequenced strains of the heterogeneous R. solanacearum species complex can degrade SA via gentisic acid to pyruvate and fumarate. R. solanacearum strain GMI1000 expresses this SA degradation pathway during tomato pathogenesis. Transcriptional analysis revealed that subinhibitory SA levels induced expression of the SA degradation pathway, toxin efflux pumps, and some general stress responses. Interestingly, SA treatment repressed expression of virulence factors, including the type III secretion system, suggesting that this pathogen may suppress virulence functions when stressed. A GMI1000 mutant lacking SA degradation activity was much more susceptible to SA toxicity but retained the wild-type colonization ability and virulence on tomato. This may be because SA is less important than gentisic acid in tomato defense signaling. However, another host, tobacco, responds strongly to SA. To test the hypothesis that SA degradation contributes to virulence on tobacco, we measured the effect of adding this pathway to the tobacco-pathogenic R. solanacearum strain K60, which lacks SA degradation genes. Ectopic addition of the GMI1000 SA degradation locus, including adjacent genes encoding two porins and a LysR-type transcriptional regulator, significantly increased the virulence of strain K60 on tobacco. Together, these results suggest that R. solanacearum degrades plant SA to protect itself from inhibitory levels of this compound and also to enhance its virulence on plant hosts like tobacco that use SA as a defense signal molecule.ImportancePlant pathogens such as the bacterial wilt agent Ralstonia solanacearum threaten food and economic security by causing significant losses for small- and large-scale growers of tomato, tobacco, banana, potato, and ornamentals. Like most plants, these crop hosts use salicylic acid (SA) both indirectly as a signal to activate defenses and directly as an antimicrobial chemical. We found that SA inhibits growth of R. solanacearum and induces a general stress response that includes repression of multiple bacterial wilt virulence factors. The ability to degrade SA reduces the pathogen's sensitivity to SA toxicity and increases its virulence on tobacco.

Project description:BACKGROUND:Plant elicitor peptides (Peps) are endogenous molecules that induce and amplify the first line of inducible plant defense, known as pattern-triggered immunity, contributing to protect plants against attack by bacteria, fungi and herbivores. Pep topic application and transgenic expression have been found to enhance disease resistance in a small number of model plant-pathogen systems. The action of Peps relies on perception by specific receptors, so displaying a family-specific activity. Recently, the presence and activity of Peps within the Rosaceae has been demonstrated. Here we characterized the population of Pep sequences within the economically important plant family of Rosaceae, with special emphasis on the Amygdaleae and Pyreae tribes, which include the most relevant edible species such as apple, pear and peach, and numerous ornamental and wild species (e.g. photinia, firethorn and hawthorn). RESULTS:The systematic experimental search for Pep and the corresponding precursor PROPEP sequences within 36 Amygdaleae and Pyreae species, and 100 cultivars had a highly homogeneous pattern, with two tribe-specific Pep types per plant, i.e. Pep1 and Pep2 (Amygdaleae) or Pep3 and Pep4 (Pyreae). Pep2 and Pep3 are highly conserved, reaching identity percentages similar to those of genes used in plant phylogenetic analyses, while Pep1 and Pep4 are somewhat more variable, with similar values to the corresponding PROPEPs. In contrast to Pep3 and Pep4, Pep1 and Pep2 sequences of different species paralleled their phylogenetic relationships, and putative ancestor sequences were identified. The large amount of sequences allowed refining of a C-terminal consensus sequence that would support the protective activity of Pep1-4 in a Prunus spp. and Xanthomonas arboricola pv. pruni system. Moreover, tribe-specific consensus sequences were deduced at the center and C-terminal regions of Peps, which might explain the higher protection efficiencies described upon topic treatments with Peps from the same tribe. CONCLUSIONS:The present study substantially enhances the knowledge on Peps within the Amygdaleae and Pyreae species. It can be the basis to design and fine-tune new control tools against important plant pathogens affecting Prunus, Pyrus and Malus species.

Dataset Information

Ralstonia solanacearum elicitor RipX Induces Defense Reaction by Suppressing the Mitochondrial atpA Gene in Host Plant.

Publications

<i>Ralstonia solanacearum</i> elicitor RipX Induces Defense Reaction by Suppressing the Mitochondrial <i>atpA</i> Gene in Host Plant.

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