Effectors, chaperones, and harpins of the Type III secretion system in the fire blight pathogen Erwinia amylovora: a review

Yuan, Xiaochen; Hulin, Michelle T.; Sundin, George W.

doi:10.1007/s42161-020-00623-1

Cited by 30 publications

(12 citation statements)

References 153 publications

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“…S7) between NlVgC and LsVgC explains the difference in their functions. Indeed, changes in amino acid sequence can affect the activity of effectors in insects and pathogens (Rao et al ., 2019; Yuan et al ., 2021; Shih et al ., 2023). It should also be noted that silencing Vg (decreasing levels of both VgC and VgN) significantly decreased the induction of JA‐Ile production by SBPH and WBPH ovary extracts when applied to mechanically wounded plants (Fig.…”

Section: Discussionmentioning

confidence: 99%

The N‐terminal subunit of vitellogenin in planthopper eggs and saliva acts as a reliable elicitor that induces defenses in rice

Zeng

et al. 2023

New Phytologist

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Summary Vitellogenins (Vgs) are critical for the development and fecundity of insects. As such, these essential proteins can be used by plants to reliably sense the presence of insects. We addressed this with a combination of molecular and chemical analyses, genetic transformation, bioactivity tests, and insect performance assays. The small N‐terminal subunit of Vgs of the planthopper Nilaparvata lugens (NlVgN) was found to trigger strong defense responses in rice when it enters the plants during feeding or oviposition by the insect. The defenses induced by NlVgN not only decreased the hatching rate of N. lugens eggs, but also induced volatile emissions in plants, which rendered them attractive to a common egg parasitoid. VgN of other planthoppers triggered the same defenses in rice. We further show that VgN deposited during planthopper feeding compared with during oviposition induces a somewhat different response, probably to target the appropriate developmental stage of the insect. We also confirm that NlVgN is essential for planthopper growth, development, and fecundity. This study demonstrates that VgN in planthopper eggs and saliva acts as a reliable and unavoidable elicitor of plant defenses. Its importance for insect performance precludes evolutionary adaptions to prevent detection by rice plants.

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Section: Discussionmentioning

confidence: 99%

The N‐terminal subunit of vitellogenin in planthopper eggs and saliva acts as a reliable elicitor that induces defenses in rice

Zeng

et al. 2023

New Phytologist

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“…Although specific evidence demonstrating that osmotic pressure physically spreads E. amylovora cells on surfaces is lacking, our data showed that water potential indeed positively contributes to sliding, and Yan et al ( 2017 ) reported that an osmotic pressure differential could draw water into the secreted EPS matrix. Furthermore, T3SS and the type III effector DspA/E are pathogenicity factors of E. amylovora (Oh et al, 2005 ; Yuan, Hulin, & Sundin, 2021 ). A study conducted in P. syringae demonstrated that AvrE1, an E. amylovora DspA/E homologue, promotes stomatal closure and the occurrence of water‐soaking lesions in host plants (Xin et al, 2016 ), and a similar phenotype has been reported in X .…”

Section: Discussionmentioning

confidence: 99%

Exopolysaccharides amylovoran and levan contribute to sliding motility in the fire blight pathogen Erwinia amylovora

Yuan

Eldred

Sundin

2022

Environmental Microbiology

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Summary Erwinia amylovora, the causative agent of fire blight, uses flagella‐based motilities to translocate to host plant natural openings; however, little is known about how this bacterium migrates systemically in the apoplast. Here, we reveal a novel surface motility mechanism, defined as sliding, in E. amylovora. Deletion of flagella assembly genes did not affect this movement, whereas deletion of biosynthesis genes for the exopolysaccharides (EPSs) amylovoran and levan resulted in non‐sliding phenotypes. Since EPS production generates osmotic pressure that potentially powers sliding, we validated this mechanism by demonstrating that water potential positively contributes to sliding. In addition, no sliding was observed when the water potential of the surface was lower than −0.5 MPa. Sliding is a passive motility mechanism. We further show that the force of gravity plays a critical role in directing E. amylovora sliding on unconfined surfaces but has a negligible effect when cells are sliding in confined microcapillaries, in which EPS‐dependent osmotic pressure acts as the main force. Although amylovoran and levan are both required for sliding, we demonstrate that they exhibit different roles in bacterial communities. In summary, our study provides fundamental knowledge for a better understanding of mechanisms that drive bacterial sliding motility.

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“…The economic importance of the Gram-negative bacterium Erwinia amylovora (fire blight, Enterobacteriaceae) is increasing with the outbreak of old disease bacterial speck of apple and pear and other commercial and ornamental Rosaceae host plants [ 1 ]. E. amylovora secretes effectors and proteins that are involved in the hypersensitive response and pathogenicity [ 2 ]. Plants are sessile, multicellular organisms that rely on developmental and metabolic changes for growth.…”

Section: Introductionmentioning

confidence: 99%

Bacterial Volatiles (mVOC) Emitted by the Phytopathogen Erwinia amylovora Promote Arabidopsis thaliana Growth and Oxidative Stress

et al. 2023

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Phytopathogens are well known for their devastating activity that causes worldwide significant crop losses. However, their exploitation for crop welfare is relatively unknown. Here, we show that the microbial volatile organic compound (mVOC) profile of the bacterial phytopathogen, Erwinia amylovora, enhances Arabidopsis thaliana shoot and root growth. GC-MS head-space analyses revealed the presence of typical microbial volatiles, including 1-nonanol and 1-dodecanol. E. amylovora mVOCs triggered early signaling events including plasma transmembrane potential Vm depolarization, cytosolic Ca2+ fluctuation, K+-gated channel activity, and reactive oxygen species (ROS) and nitric oxide (NO) burst from few minutes to 16 h upon exposure. These early events were followed by the modulation of the expression of genes involved in plant growth and defense responses and responsive to phytohormones, including abscisic acid, gibberellin, and auxin (including the efflux carriers PIN1 and PIN3). When tested, synthetic 1-nonanol and 1-dodecanol induced root growth and modulated genes coding for ROS. Our results show that E. amylovora mVOCs affect A. thaliana growth through a cascade of early and late signaling events that involve phytohormones and ROS.

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Effectors, chaperones, and harpins of the Type III secretion system in the fire blight pathogen Erwinia amylovora: a review

Cited by 30 publications

References 153 publications

The N‐terminal subunit of vitellogenin in planthopper eggs and saliva acts as a reliable elicitor that induces defenses in rice

The N‐terminal subunit of vitellogenin in planthopper eggs and saliva acts as a reliable elicitor that induces defenses in rice

Exopolysaccharides amylovoran and levan contribute to sliding motility in the fire blight pathogen Erwinia amylovora

Bacterial Volatiles (mVOC) Emitted by the Phytopathogen Erwinia amylovora Promote Arabidopsis thaliana Growth and Oxidative Stress

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