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1.
Plant J ; 117(2): 516-540, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37864805

RESUMO

Bacterial fruit blotch, caused by Acidovorax citrulli, is a serious disease of melon and watermelon. The strains of the pathogen belong to two major genetic groups: group I strains are strongly associated with melon, while group II strains are more aggressive on watermelon. A. citrulli secretes many protein effectors to the host cell via the type III secretion system. Here we characterized AopW1, an effector that shares similarity to the actin cytoskeleton-disrupting effector HopW1 of Pseudomonas syringae and with effectors from other plant-pathogenic bacterial species. AopW1 has a highly variable region (HVR) within amino acid positions 147 to 192, showing 14 amino acid differences between group I and II variants. We show that group I AopW1 is more toxic to yeast and Nicotiana benthamiana cells than group II AopW1, having stronger actin filament disruption activity, and increased ability to induce cell death and reduce callose deposition. We further demonstrated the importance of some amino acid positions within the HVR for AopW1 cytotoxicity. Cellular analyses revealed that AopW1 also localizes to the endoplasmic reticulum, chloroplasts, and plant endosomes. We also show that overexpression of the endosome-associated protein EHD1 attenuates AopW1-induced cell death and increases defense responses. Finally, we show that sequence variation in AopW1 plays a significant role in the adaptation of group I and II strains to their preferred hosts, melon and watermelon, respectively. This study provides new insights into the HopW1 family of bacterial effectors and provides first evidence on the involvement of EHD1 in response to biotic stress.


Assuntos
Citrullus , Comamonadaceae , Cucurbitaceae , Adaptação ao Hospedeiro , Doenças das Plantas/microbiologia , Citrullus/genética , Aminoácidos
2.
Plant Cell Rep ; 41(2): 337-345, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34817656

RESUMO

KEY MESSAGE: The application of flagellin 22 (flg22), the most widely studied PAMP, enhance crop cold tolerance. ICE1-CBF pathway and SA signaling is involved in the alleviation of cold injury by flg22 treatment. Pathogen infection cross-activates cold response and increase cold tolerance of host plants. However, it is not possible to use the infection to increase cold tolerance of field plants. Here flagellin 22 (flg22), the most widely studied PAMP (pathogen-associated molecular patterns), was used to mimic the pathogen infection to cross-activate cold response. Flg22 treatment alleviated the injury caused by freezing in Arabidopsis, oilseed and tobacco. In Arabidopsis, flg22 activated the expression of immunity and cold-related genes. Moreover, the flg22 induced alleviation of cold injury was lost in NahG transgenic line (SA-deficient), sid2-2 and npr1-1 mutant plants, and flg22-induced expression of cold tolerance-related genes, which indicating that salicylic acid signaling pathway is required for the alleviation of cold injury by flg22 treatment. In short flg22 application can be used to enhance cold tolerance in field via a salicylic acid-depended pathway.


Assuntos
Resposta ao Choque Frio/fisiologia , Flagelina/farmacologia , Moléculas com Motivos Associados a Patógenos/imunologia , Imunidade Vegetal/fisiologia , Plântula/fisiologia , Arabidopsis/efeitos dos fármacos , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Brassica napus/efeitos dos fármacos , Brassica napus/fisiologia , Clorofila/metabolismo , Resposta ao Choque Frio/imunologia , Produtos Agrícolas/imunologia , Congelamento , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Transferases Intramoleculares/genética , Moléculas com Motivos Associados a Patógenos/metabolismo , Plantas Geneticamente Modificadas , Ácido Salicílico/metabolismo , Plântula/efeitos dos fármacos , Nicotiana/efeitos dos fármacos , Nicotiana/fisiologia
3.
Plant Cell Environ ; 43(3): 801-817, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31851376

RESUMO

Abiotic stresses greatly affect the immunity of plants. However, it is unknown whether pathogen infection affects abiotic stress tolerance of host plants. Here, the effect of defense response on cold and heat tolerance of host plants was investigated in Pst DC3000-infected Arabidopsis plants, and it was found that the pathogen-induced defense response could alleviate the injury caused by subsequent cold and heat stress (38°C). Transcriptomic sequencing plus RT-qPCR analyses showed that some abiotic stress genes are up-regulated in transcription by pathogen infection, including cold signaling components ICE1, CBF1, and CBF3, and some heat signaling components HSFs and HSPs. Moreover, the pathogen-induced alleviation of cold and heat injury was lost in NahG transgenic line (SA-deficient), sid2-2 and npr1-1 mutant plants, and pathogen-induced expression of cold and heat tolerance-related genes such as CBFs and HSPs, respectively, was lost or compromised in these plants, indicating that salicylic acid signaling pathway is required for the alleviation of cold and heat injury by pathogen infection. In short, our current work showed that in fighting against pathogens, host plants also enhance their cold and heat tolerance via a salicylic acid-dependent pathway.


Assuntos
Arabidopsis/microbiologia , Congelamento , Temperatura Alta , Pseudomonas syringae/fisiologia , Ácido Salicílico/metabolismo , Arabidopsis/citologia , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Sobrevivência Celular , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Interações Hospedeiro-Patógeno , Fenótipo , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Estresse Fisiológico/genética , Transcrição Gênica , Transcriptoma/genética
4.
Plant Cell Environ ; 42(9): 2645-2663, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31087367

RESUMO

Exposure to short-term cold stress influences disease resistance by mechanisms that remain poorly characterized. The molecular basis of cold-activated immunity was therefore investigated in Arabidopsis thaliana inoculated with the bacterial pathogen Pst DC3000, using a transcriptomic analysis. Exposure to cold stress for 10 hr was sufficient to activate immunity, as well as H2 O2 accumulation and callose deposition. Transcriptome changes induced by the 10-hr cold treatment were similar to those caused by pathogen infection, including increased expression of the salicylic acid (SA) pathway marker genes, PR2 and PR5, and genes playing positive roles in defence against (hemi)-biotrophs. In contrast, transcripts encoding jasmonic acid (JA) pathway markers such as PR4 and MYC2 and transcripts with positive roles in defence against necrotrophs were less abundant following the 10-hr cold treatment. Cold-activated immunity was dependent on SA, being partially dependent on NPR1 and ICS1/SID2. In addition, transcripts encoding SA biosynthesis enzymes such as ICS2, PAL1, PAL2, and PAL4 (but not ICS1/SID2) and MES9 were more abundant, whereas GH3.5/WES1 and SOT12 transcripts that encode components involved in SA modification were less abundant following cold stress treatment. These findings show that cold stress cross-activates innate immune responses via a SA-dependent pathway.


Assuntos
Arabidopsis/imunologia , Resposta ao Choque Frio , Resistência à Doença , Ácido Salicílico/metabolismo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Ciclopentanos/metabolismo , Regulação da Expressão Gênica de Plantas , Glucanos/metabolismo , Peróxido de Hidrogênio/metabolismo , Oxilipinas/metabolismo , Pseudomonas syringae
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