Impact of salicylic acid- and jasmonic acid-regulated defences on root colonization by Trichoderma harzianum T-78.
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ABSTRACT:
SUBMITTER: Martinez-Medina A
PROVIDER: S-EPMC5616143 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Trichoderma is a soil-borne fungal genus that includes species with a significant impact on agriculture and industrial processes. Some Trichoderma strains exert beneficial effects in plants through root colonization, although little is known about how this interaction takes place. To better understand this process, the root colonization of wild-type Arabidopsis and the salicylic acid (SA)-impaired mutant sid2 by a green fluorescent protein (GFP)-marked Trichoderma harzianum strain was followed under confocal microscopy. Trichoderma harzianum GFP22 was able to penetrate the vascular tissue of the sid2 mutant because of the absence of callose deposition in the cell wall of root cells. In addition, a higher colonization of sid2 roots by GFP22 compared with that in Arabidopsis wild-type roots was detected by real-time polymerase chain reaction. These results, together with differences in the expression levels of plant defence genes in the roots of both interactions, support a key role for SA in Trichoderma early root colonization stages. We observed that, without the support of SA, plants were unable to prevent the arrival of the fungus in the vascular system and its spread into aerial parts, leading to later collapse.
| S-EPMC6638820 | biostudies-literature
Project description:Research on the interaction between the non-nodule-forming bacterial endophytes and their host plants is still in its infancy. Especially the understanding of plant control mechanisms which govern endophytic colonization is very limited. The current study sets out to determine which hormonal signaling pathway controls endophytic colonization in rice, and whether the mechanisms deviate for a pathogen. The endophyte Azoarcus olearius BH72-rice model was used to investigate root responses to endophytes in comparison to the recently established pathosystem of rice blight Xanthomonas oryzae pv. oryzae PXO99 (Xoo) in flooded roots. In the rice root transcriptome, 523 or 664 genes were found to be differentially expressed in response to Azoarcus or Xoo colonization, respectively; however, the response was drastically different, with only 6% of the differentially expressed genes (DEGs) overlapping. Overall, Xoo infection induced a much stronger defense reaction than Azoarcus colonization, with the latter leading to down-regulation of many defense related DEGs. Endophyte-induced DEGs encoded several enzymes involved in phytoalexin biosynthesis, ROS (reactive oxygen species) production, or pathogenesis-related (PR) proteins. Among putative plant markers related to signal transduction pathways modulated exclusively during Azoarcus colonization, none overlapped with previously published DEGs identified for another rice endophyte, Azospirillum sp. B510. This suggests a large variation in responses of individual genotypic combinations. Interestingly, the DEGs related to jasmonate (JA) signaling pathway were found to be consistently activated by both beneficial endophytes. In contrast, the salicylate (SA) pathway was activated only in roots infected by the pathogen. To determine the impact of SA and JA production on root colonization by the endophyte and the pathogen, rice mutants with altered hormonal responses were employed: mutant cpm2 deficient in jasmonate synthesis, and RNA interference (RNAi) knockdown lines of NPR1 decreased in salicylic acid-mediated defense responses (NPR1-kd). Only in cpm2, endophytic colonization of Azoarcus was significantly increased, while Xoo colonization was not affected. Surprisingly, NPR1-kd lines showed slightly decreased colonization by Xoo, contrary to published results for leaves. These outcomes suggest that JA but not SA signaling is involved in controlling the Azoarcus endophyte density in roots and can restrict internal root colonization, thereby shaping the beneficial root microbiome.
| S-EPMC7000620 | biostudies-literature
Project description:Trichoderma, widely distributed all over the world, is commonly found in soil and root ecosystems. It is a group comprising beneficial fungi that improve plant disease resistance and promote plant growth. Studies have shown that Trichoderma cellulases can also improve plant disease resistance. Based on previous studies, we reported that a C6 zinc finger protein (Thc6) regulates two cellulase genes, thph1 and thph2, to induce ISR responses in plants. Therefore, in this study, we focused on the role of thph2 in the colonization of maize roots by T. harzianum and the induction of systemic resistance against southern leaf blight. The results showed that thph2 had a positive regulatory effect on the Trichoderma colonization of maize roots. After the root was treated with Trichoderma, the leaf defense genes AOS, LOX5, HPL, and OPR1 were expressed to resist the attack of Cochliobolus heterostrophus. The pure Thph2 protein also resulted in a similar induction activity of the AOS, LOX5, HPL, and OPR1 expression in maize roots, further demonstrating that thph2 can induce plant defense responses and that signal transduction occurs mainly through the JA signaling pathway.
| S-EPMC10744625 | biostudies-literature
Project description:BackgroundTrichoderma spp. are effective biocontrol agents for many plant pathogens, thus the mechanism of Trichoderma-induced plant resistance is not fully understood. In this study, a novel Trichoderma strain was identified, which could promote plant growth and reduce the disease index of gray mold caused by Botrytis cinerea in cucumber. To assess the impact of Trichoderma inoculation on the plant response, a multi-omics approach was performed in the Trichoderma-inoculated cucumber plants through the analyses of the plant transcriptome, proteome, and phytohormone content.ResultsA novel Trichoderma strain was identified by morphological and molecular analysis, here named T. longibrachiatum H9. Inoculation of T. longibrachiatum H9 to cucumber roots promoted plant growth in terms of root length, plant height, and fresh weight. Root colonization of T. longibrachiatum H9 in the outer layer of epidermis significantly inhibited the foliar pathogen B. cinerea infection in cucumber. The plant transcriptome and proteome analyses indicated that a large number of differentially expressed genes (DEGs) and differentially expressed proteins (DEPs) were identified in cucumber plants 96 h post T. longibrachiatum H9 inoculation. Up-regulated DEGs and DEPs were mainly associated with defense/stress processes, secondary metabolism, and phytohormone synthesis and signaling, including jasmonic acid (JA), ethylene (ET) and salicylic acid (SA), in the T. longibrachiatum H9-inoculated cucumber plants in comparison to untreated plants. Moreover, the JA and SA contents significantly increased in cucumber plants with T. longibrachiatum H9 inoculation.ConclusionsApplication of T. longibrachiatum H9 to the roots of cucumber plants effectively promoted plant growth and significantly reduced the disease index of gray mold caused by B. cinerea. The analyses of the plant transcriptome, proteome and phytohormone content demonstrated that T. longibrachiatum H9 mediated plant systemic resistance to B. cinerea challenge through the activation of signaling pathways associated with the phytohormones JA/ET and SA in cucumber.
| S-EPMC6379975 | biostudies-literature
Project description:In the present study, we investigated the role of Trichoderma virens (TriV_JSB100) spores or cell-free culture filtrate in the regulation of growth and activation of the defence responses of tomato (Solanum lycopersicum) plants against Fusarium oxysporum f. sp. lycopersici by the development of a biocontrol-plant-pathogen interaction system. Two-week-old tomato seedlings primed with TriV_JSB100 spores cultured on barley grains (BGS) or with cell-free culture filtrate (CF) were inoculated with Fusarium pathogen under glasshouse conditions; this resulted in significantly lower disease incidence in tomato Oogata-Fukuju plants treated with BGS than in those treated with CF. To dissect the pathways associated with this response, jasmonic acid (JA) and salicylic acid (SA) signalling in BGS- and CF-induced resistance was evaluated using JA- and SA-impaired tomato lines. We observed that JA-deficient mutant def1 plants were susceptible to Fusarium pathogen when they were treated with BGS. However, wild-type (WT) BGS-treated tomato plants showed a higher JA level and significantly lower disease incidence. SA-deficient mutant NahG plants treated with CF were also found to be susceptible to Fusarium pathogen and displayed low SA levels, whereas WT CF-treated tomato plants exhibited moderately lower disease levels and substantially higher SA levels. Expression of the JA-responsive defensin gene PDF1 was induced in WT tomato plants treated with BGS, whereas the SA-inducible pathogenesis-related protein 1 acidic (PR1a) gene was up-regulated in WT tomato plants treated with CF. These results suggest that TriV_JSB100 BGS and CF differentially induce JA and SA signalling cascades for the elicitation of Fusarium oxysporum resistance in tomato.
| S-EPMC6638079 | biostudies-literature
Project description:Trichoderma harzianum is one of the most beneficial microorganisms applied on diverse crops against biotic and abiotic stresses and acts also as a plant growth-promoting fungus. Here, we report the genome of T. harzianum B97, originating from a French agricultural soil and used as a biofertilizer that can tolerate abiotic stresses.
| S-EPMC5374245 | biostudies-literature
Project description:The fungal genus Trichoderma includes strains with biocontrol and/or biostimulant potential and is recognized as a source of genes with biotechnological value. In a previous study the Kelch domain protein, encoded by the Thkel1 gene of Trichoderma harzianum T34, was found to confer tolerance to salt stress when expressed in plants of Arabidopsis thaliana. In the present work, we have overexpressed Thkel1 in rapeseed plants in order to generate an additional biotechnological tool for analyzing the role of this gene in Trichoderma-plant interactions. The overexpression of this gene in Brassicaceae plants improves responses to pathogens through the induction of systemic defenses mediated by jasmonic acid, facilitates root colonization by modulating the myrosinase activity, and, as a result, increases plant productivity. These effects were also observed in Thkel1 overexpressing plants subjected to abiotic stress conditions. Additionally, the differences detected in root colonization levels by T. harzianum wild type and Thkel1 silenced transformants between Arabidopsis or rapeseed and tomato plants indicate that ThKEL1 interacts in different ways in Brassicaceae and non-Brassicaceae plants.
| S-EPMC6873215 | biostudies-literature
Project description:Aphids induce many transcriptional perturbations in their host plants, but the signalling cascades responsible and the effects on plant resistance are largely unknown. Through a genome-wide association (GWA) mapping study in Arabidopsis thaliana, we identified WRKY22 as a candidate gene associated with feeding behaviour of the green peach aphid, Myzus persicae The transcription factor WRKY22 is known to be involved in pathogen-triggered immunity, and WRKY22 gene expression has been shown to be induced by aphids. Assessment of aphid population development and feeding behaviour on knockout mutants and overexpression lines showed that WRKY22 increases susceptibility to M. persicae via a mesophyll-located mechanism. mRNA sequencing analysis of aphid-infested wrky22 knockout plants revealed the up-regulation of genes involved in salicylic acid (SA) signalling and down-regulation of genes involved in plant growth and cell-wall loosening. In addition, mechanostimulation of knockout plants by clip cages up-regulated jasmonic acid (JA)-responsive genes, resulting in substantial negative JA-SA crosstalk. Based on this and previous studies, WRKY22 is considered to modulate the interplay between the SA and JA pathways in response to a wide range of biotic and abiotic stimuli. Its induction by aphids and its role in suppressing SA and JA signalling make WRKY22 a potential target for aphids to manipulate host plant defences.
| S-EPMC4892728 | biostudies-literature
Project description:In plants, salicylic acid (SA) is a hormone that mediates a plant's defense against pathogens. SA also takes an active role in a plant's response to various abiotic stresses, including chilling, drought, salinity, and heavy metals. In addition, in recent years, numerous studies have confirmed the important role of SA in plant morphogenesis. In this review, we summarize data on changes in root morphology following SA treatments under both normal and stress conditions. Finally, we provide evidence for the role of SA in maintaining the balance between stress responses and morphogenesis in plant development, and also for the presence of SA crosstalk with other plant hormones during this process.
| S-EPMC8875895 | biostudies-literature
Project description:Red light (RL) can stimulate plant defense against foliar diseases; however, its role in activation of systemic defense against root diseases remains unclear. Here, the effect of RL on root knot nematode Meloidogyne incognita (RKN) infestation was investigated in watermelon plants (Citrullus lanatus L.). Plants were exposed to 200 μmol m-2 s-1 photosynthetic photon flux density RL at the canopy level for 21 days using light-emitting photodiodes. The results showed that RL significantly suppressed gall formation and nematode development, which was closely associated with the RL-induced attenuation of oxidative stress in roots. Gene expression analysis showed that RL caused a transient upregulation of PR1 and WRKY70 transcripts at 7 days post inoculation in RKN-infected plants. Further investigation revealed that RL-induced systemic defense against RKN was attributed to increased jasmonic acid (JA) and salicylic acid (SA) content, and transcript levels of their biosynthetic genes in roots. Interestingly, while malondialdehyde content decreased, H2O2 accumulation increased in RL-treated RKN-plants, indicating a potential signaling role of H2O2 in mediating RL-induced systemic defense. Furthermore, analysis of enzymatic and non-enzymatic antidoxidants revealed that RL-induced enhanced defense agaist RKN was also attributed to increased activities of antioxidant enzymes as well as redox homeostasis. Taken together, these findings suggest that RL could enhance systemic resistance against RKN, which is mediated by a coordinated regulation of JA- and SA-dependent signaling, antioxidants, and redox homeostasis in watermelon plants.
| S-EPMC6048386 | biostudies-literature