Elicitors and Plant Defence

The first line of plant defence responses against pathogens can be induced by the bacterial flg22 and can be dependent on various external and internal factors. Here, we firstly studied the effects of daytime and ethylene (ET) using Never ripe (Nr) mutants in the local and systemic defence responses of intact tomato plants after flg22 treatments. Flg22 was applied in the afternoon and at night and rapid reactions were detected. The production of hydrogen peroxide and nitric oxide was induced by flg22 locally, while superoxide was induced systemically, in wild type plants in the light period, but all remained lower at night and in Nr leaves. Flg22 elevated, locally, the ET, jasmonic acid (JA) and salicylic acid (SA) levels in the light period; these levels did not change significantly at night. Expression of Pathogenesis-related 1 (PR1), Ethylene response factor 1 (ERF1) and Defensin (DEF) showed also daytime- and ET-dependent changes. Enhanced ERF1 and DEF expression and stomatal closure were also observable in systemic leaves of wild type plants in the light. These data demonstrate that early biotic signalling in flg22-treated leaves and distal ones is an ET-dependent process and it is also determined by the time of day and inhibited in the early night phase.

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Zinc phosphate protects tomato plants against Pseudomonas syringae pv. tomato

Journal of Plant Diseases and Protection ◽

10.1007/s41348-021-00444-z ◽

2021 ◽

Author(s):

Mara Quaglia ◽

Marika Bocchini ◽

Benedetta Orfei ◽

Roberto D’Amato ◽

Franco Famiani ◽

...

Keyword(s):

Disease Severity ◽

Pseudomonas Syringae ◽

Zinc Phosphate ◽

Plant Defence ◽

In Planta ◽

Tomato Plants ◽

Pathogenesis Related Protein ◽

Defence Responses ◽

Plant Defence Responses

AbstractThe purpose of this study was to determine whether zinc phosphate treatments of tomato plants (Solanum lycopersicum L.) can attenuate bacterial speck disease severity through reduction of Pseudomonas syringae pv. tomato (Pst) growth in planta and induce morphological and biochemical plant defence responses. Tomato plants were treated with 10 ppm (25.90 µM) zinc phosphate and then spray inoculated with strain DAPP-PG 215, race 0 of Pst. Disease symptoms were recorded as chlorosis and/or necrosis per leaf (%) and as numbers of necrotic spots. Soil treatments with zinc phosphate protected susceptible tomato plants against Pst, with reductions in both disease severity and pathogen growth in planta. The reduction of Pst growth in planta combined with significantly higher zinc levels in zinc-phosphate-treated plants indicated direct antimicrobial toxicity of this microelement, as also confirmed by in vitro assays. Morphological (i.e. callose apposition) and biochemical (i.e., expression of salicylic-acid-dependent pathogenesis-related protein PR1b1 gene) defence responses were induced by the zinc phosphate treatment, as demonstrated by histochemical and qPCR analyses, respectively. In conclusion, soil treatments with zinc phosphate can protect tomato plants against Pst attacks through direct antimicrobial activity and induction of morphological and biochemical plant defence responses.

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In vitro inhibition of shikimate hydroxycinnamoyltransferase by acibenzolar acid, the first metabolite of the plant defence inducer acibenzolar-S-methyl.

Plant Physiology and Biochemistry ◽

10.1016/j.plaphy.2021.03.050 ◽

2021 ◽

Author(s):

Jonathan Negrel ◽

Agnès Klinguer ◽

Marielle Adrian

Keyword(s):

Plant Defence ◽

In Vitro Inhibition

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Integrating metabolomics and targeted gene expression to uncover potential biomarkers of fungal/oomycetes-associated disease susceptibility in grapevine

Scientific Reports ◽

10.1038/s41598-020-72781-2 ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 1

Author(s):

Marisa Maia ◽

António E. N. Ferreira ◽

Rui Nascimento ◽

Filipa Monteiro ◽

Francisco Traquete ◽

...

Keyword(s):

Gene Expression ◽

Plant Defence ◽

Breeding Programs ◽

Analysis Group ◽

Expression Of Genes ◽

Leucoanthocyanidin Reductase ◽

Defence Responses ◽

Targeted Gene Expression ◽

Plant Defence Responses ◽

First Time

Abstract Vitis vinifera, one of the most cultivated fruit crops, is susceptible to several diseases particularly caused by fungus and oomycete pathogens. In contrast, other Vitis species (American, Asian) display different degrees of tolerance/resistance to these pathogens, being widely used in breeding programs to introgress resistance traits in elite V. vinifera cultivars. Secondary metabolites are important players in plant defence responses. Therefore, the characterization of the metabolic profiles associated with disease resistance and susceptibility traits in grapevine is a promising approach to identify trait-related biomarkers. In this work, the leaf metabolic composition of eleven Vitis genotypes was analysed using an untargeted metabolomics approach. A total of 190 putative metabolites were found to discriminate resistant/partial resistant from susceptible genotypes. The biological relevance of discriminative compounds was assessed by pathway analysis. Several compounds were selected as promising biomarkers and the expression of genes coding for enzymes associated with their metabolic pathways was analysed. Reference genes for these grapevine genotypes were established for normalisation of candidate gene expression. The leucoanthocyanidin reductase 2 gene (LAR2) presented a significant increase of expression in susceptible genotypes, in accordance with catechin accumulation in this analysis group. Up to our knowledge this is the first time that metabolic constitutive biomarkers are proposed, opening new insights into plant selection on breeding programs.

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Chitosan increases Pinus pinaster tolerance to the pinewood nematode (Bursaphelenchus xylophilus) by promoting plant antioxidative metabolism

Scientific Reports ◽

10.1038/s41598-021-83445-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Marta Nunes da Silva ◽

Carla S. Santos ◽

Ana Cruz ◽

Adrián López-Villamor ◽

Marta W. Vasconcelos

Keyword(s):

Phenolic Compounds ◽

Pinus Pinaster ◽

Plant Defence ◽

Pine Wilt Disease ◽

Bursaphelenchus Xylophilus ◽

Nematode Population ◽

Post Inoculation ◽

Pinewood Nematode ◽

Plant Tolerance ◽

The Moment

AbstractThe pine wilt disease (PWD), for which no effective treatment is available at the moment, is a constant threat to Pinus spp. plantations worldwide, being responsible for significant economic and environmental losses every year. It has been demonstrated that elicitation with chitosan increases plant tolerance to the pinewood nematode (PWN) Bursaphelenchus xylophilus, the causal agent of the PWD, but the biochemical and genetic aspects underlying this response have not been explored. To understand the influence of chitosan in Pinus pinaster tolerance against PWN, a low-molecular-weight (327 kDa) chitosan was applied to mock- and PWN-inoculated plants. Nematode population, malondialdehyde (MDA), catalase, carotenoids, anthocyanins, phenolic compounds, lignin and gene expression related to oxidative stress (thioredoxin 1, TRX) and plant defence (defensin, DEF, and a-farnesene synthase, AFS), were analysed at 1, 7, 14, 21 and 28 days post-inoculation (dpi). At 28 dpi, PWN-infected plants elicited with chitosan showed a sixfold lower nematode population when compared to non-elicited plants. Higher levels of MDA, catalase, carotenoids, anthocyanins, phenolic compounds, and lignin were detected in chitosan-elicited plants following infection. The expression levels of DEF gene were higher in elicited plants, while TRX and AFS expression was lower, possibly due to the disease containment-effect of chitosan. Combined, we conclude that chitosan induces pine defences against PWD via modulation of metabolic and transcriptomic mechanisms related with plant antioxidant system.

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