Mock Plants Research Articles

First report of Colletotrichum plurivorum and Colletotrichum truncatum causing anthracnose on melon plants in Brazil.

Melon (Cucumis melo L.) is an economically important crop in Brazil, with an annual production of 699.281 tons (FAO 2024). Fungal diseases are one of the biggest problems in melon production, and melon growers in northeastern Brazil have reported over 80% of plants showing anthracnose symptoms in the fields during rainy seasons. Plants were wilted, displaying brown necrotic lesions and water-soaked spots with yellowish edges on the leaves and vines. Melon fruits displayed necrotic lesions on the outside. From June 2022 to June 2023, melon leaves (varieties Yellow, Galia, and Cantaloupe) from anthracnose-symptomatic plants were collected in four melon farms located in the municipalities of Afonso Bezerra, Mossoró, Tibau, and Upanema in the state of Rio Grande do Norte. Small fragments of symptomatic leaves were disinfected in 70% ethanol (30 sec) and 2.5 % sodium hypochlorite (1 min), rinsed in sterile distilled water, and plated on PDA Petri dishes with tetracycline (0.05g/liter). Plates were maintained in a bio-oxygen demand incubator (BOD) for 3 days at 28 ± 2 °C, under a 12 hr photoperiod. Eleven representative fungal colonies resembling Colletotrichum spp. were selected and monosporically grown on PDA for seven days for morphology, pathogenicity, and molecular analyses.ight colonies showed pinkish-dark brown with acervuli in the center and cottony mycelium, and showing black edges in some isolates, resembling C. plurivorum (Zhang et al. 2023). Conidia from those colonies were hyaline, cylindrical with obtuse ends, and 17.76 x 7.06 μm, n= 50. Three colonies developed pinkish-gray mycelia with numerous black microsclerotia, and the conidia were hyaline, falcate, and 27.38 x 4.10 μm, n= 50, resembling C. truncatum (Yu et al. 2023). The total DNA of the eleven isolates was extracted, and the internal transcribed space (ITS), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), actin (ACT), β-tubulin (TUB), and chitin synthase 1 (CHS-1) regions were partially amplified by PCR. Amplicons were sequenced and deposited to Genbank (Table eXtra1). A phylogenetic tree was built with the Maximum likelihood method with the concatenated sequences of the five partial gene sequences on Software MEGA (Version 11.0.10) (Tamura et al. 2021). The isolates CML5, CML8, CML9, CML10, CML11, CML14, CML15, and CML25 were grouped with Colletotrichum plurivorum CBS 125474 (orchidearum complex), and the isolates CML26, CML27 and CML28 with Colletotrichum truncatum CBS 15:35 (truncatum complex) with 87 % e 97 % of Bootstrap support, respectively. C. plurivorum was detected in four farms visited (we selected two representative isolates per farm), while C. truncatum isolates were all from the farm in Afonso Bezerra municipality. A pathogenicity test was performed following the method of Baishuan et al. (2023), micro-injuries were made in leaves of melon seedlings 'Goldex Yellow' and inoculated with a spore suspension of colonies with seven days of growth (106 spore/mL) of each isolate and sprayed to the point of dripping. Sterile water was used as mock. After nine days, anthracnose symptoms similar to those observed in the field were seen in all inoculated leaves, while no symptom was observed in the leaves of the mock plants. The pathogens were reisolated and their identification was confirmed by morphology and sequencing. Five seedlings were inoculated per isolate and mock, the assay was repeated, and the same results were observed. The species C. plurivorum has already been reported to cause disease in Cucumbers in Brazil (Silva et al. 2023) and C. plurivorum and C. truncatum in Citrullus lanatus in China (Guo et al. 2022). To the best of our knowledge, this is the first report of C. plurivorum and C. truncatum causing anthracnose in melon plants in Brazil.

Eco‐friendly chitosan polymer mitigates disease severity and mediates plant resistance against Beet curly top Iran virus in tomato

AbstractA tomato‐infecting virus known as Beet curly top Iran virus (BCTIV) cause a significant disease for tomato plants and several other plant species around the world. Chitosan polysaccharide is a natural biopolymer that has been utilised as an exo‐elicitor to enhance plant defence mechanisms against a variety of plant diseases. This study investigates the efficacy of chitosan in combating BCTIV disease on tomato plants and modulating the host–virus interaction under greenhouse conditions. Twenty‐four hours before the virus inoculation, tomato plants were sprayed with a protective chitosan solution at different concentrations (0.5, 1, 1.5, and 2 mg/mL). Tomato plants were inoculated with a BCTIV infectious clone using an Agrobacterium‐inoculation method. The findings clearly demonstrated a reduction in the severity of the disease in chitosan‐treated plants as compared to Mock‐plants, with the percentage decreasing from 61.53% to 75.28% in 1.5 mg/mL treated plants and from 9.01% to 28.43% in 0.5 mg/mL treated plants. In addition, the utilisation of chitosan has the potential to deactivate the accumulation of BCTIV within the host tissues. The virus accumulation was greatly alleviated in 1, 1.5, and 2 mg/mL‐treated plants by 71.29%, 90.11%, and 93.14%, respectively, and over the mock plants. Furthermore, it was found that chitosan applied at all tested concentrations increased the relative expression and mRNA accumulation of genes related to resistance, including the pathogenesis‐related protein gene PR‐1, the HSP90 gene, and the AGO2a antiviral gene. These genes reached their maximum by 22.9‐, 12.93‐, and 4.44‐fold increases, respectively, over the untreated control. According to gas chromatography–mass spectroscop (GC‐MS) fractionation profile, chitosan increased 28 bioactive metabolic components, such as n‐hexadecanoic acid, heptanone, 1,2‐dimethylbenzene, dicarboxylic acid, and cis‐11‐octadecenoic acid methyl‐ester, to improve metabolic pathways. Results reported here revealed that foliar application of chitosan decreases the rate of the disease severity and virus accumulation in BCTIV‐infected tomato plants. This effect is associated with increased gene expression and defence‐related factors, enhancing tomato resistance to BCTIV infection. Consequently, chitosan treatments could be part of an integrated approach for reducing the severity of BCTIV disease in tomato and other host plants.

PvSPS4 is involved in regulation of root sugar balance in common bean under salt stress

Salinity is a stress factor that decreases global agricultural yield. Crops such as rice, tomato, potato, and legumes are susceptible to salt, thus this problem requires urgent attention. Disruption of carbohydrate metabolism can have negative effects on stress tolerance. Sucrose phosphate synthase (SPS) enzymes operate in a key regulatory step in sucrose synthesis. Therefore, they have a significant role in the regulation of sugar metabolism. This study focused on the function of the SPS homolog -pvSPS4- in the roots of legume crop common bean under salinity stress. We previously showed that pvSPS4 expression is root-specific and is upregulated under salt stress in a salt-tolerant common bean genotype. This upregulation was accompanied by an accumulation of sugars in the roots. In the current study, using the same genotype, we generated composite common bean plants with wild-type shoot and pvSPS4 knock-down roots. Composite plants exhibited a more sensitive phenotype under salt stress compared to control and mock plants. pvSPS4 knock-down disturbed the root glucose/sucrose ratio and balance of Ca+2, Mg+2, and K+ in both root and leaves which resulted in a reduction in photosynthetic pigments together with osmoregulation and antioxidant capability. Our results imply that pvSPS4 is an important gene for carbohydrate balance regulation under salt-stress in the common bean root tissues and sets an example for the significance of mainly disregarded roles of SPS genes in sink tissues.

Co-expression of stress-responsive regulatory genes, MuNAC4, MuWRKY3 and MuMYB96 associated with resistant-traits improves drought adaptation in transgenic groundnut (Arachis hypogaea l.) plants.

Groundnut, cultivated under rain-fed conditions is prone to yield losses due to intermittent drought stress. Drought tolerance is a complex phenomenon and multiple gene expression required to maintain the cellular tolerance. Transcription factors (TFs) regulate many functional genes involved in tolerance mechanisms. In this study, three stress-responsive regulatory TFs cloned from horse gram, (Macrotyloma uniflorum (Lam) Verdc.), MuMYB96, involved in cuticular wax biosynthesis; MuWRKY3, associated with anti-oxidant defense mechanism and MuNAC4, tangled with lateral root development were simultaneously expressed to enhance drought stress resistance in groundnut (Arachis hypogaea L.). The multigene transgenic groundnut lines showed reduced ROS production, membrane damage, and increased superoxide dismutase (SOD) and ascorbate peroxidase (APX) enzyme activity, evidencing improved antioxidative defense mechanisms under drought stress. Multigene transgenic plants showed lower proline content, increased soluble sugars, epicuticular wax content and higher relative water content suggesting higher maintenance of tissue water status compared to wildype and mock plants. The scanning electron microscopy (SEM) analysis showed a substantial increase in deposition of cuticular waxes and variation in stomatal number in multigene transgenic lines compared to wild type and mock plants. The multigene transgenic plants showed increased growth of lateral roots, chlorophyll content, and stay-green nature in drought stress compared to wild type and mock plants. Expression analysis of transgenes, MuMYB96, MuWRKY3, and MuNAC4 and their downstream target genes, KCS6, KCR1, APX3, CSD1, LBD16 and DBP using qRT-PCR showed a two- to four-fold increase in transcript levels in multigene transgenic groundnut plants over wild type and mock plants under drought stress. Our study demonstrate that introducing multiple genes with simultaneous expression of genes is a viable option to improve stress tolerance and productivity under drought stress.

In planta Female Flower Agroinfiltration Alters the Cannabinoid Composition in Industrial Hemp (Cannabis sativa L.).

Industrial hemp is a diploid (2n = 20), dioecious plant, and an essential source of various phytochemical productions. More than 540 phytochemicals have been described, some of which proved helpful in the remedial treatment of human diseases. Therefore, further study of hemp phytochemicals in medicine is highly anticipated. Previously, we developed the vacuum agroinfiltration method, which allows the transient gene expression in hemp tissues including female flowers, where cannabinoids are produced and accumulated. In this study, we attempted to alter the composition of total CBD and THC. The RT-PCR and sanger sequence identified eleven copies of the CBDAS gene, two copies of the THCAS gene, and one CBCAS gene. Binary vectors were constructed to overexpress the CBDAS gene and silence the THCAS gene via RNA interference. The Transcript level of the CBDAS gene was increased by more than 10 times than the plants used as a control, which led to a 54% higher total CBD content. The silencing of the THCAS gene led to downregulation of the THCAS gene, with an 80% reduction in transcript levels, and total THC content was reduced to 43% compared with mock plant. These results suggest that hemp vacuum infiltration is highly effective for metabolic engineering of cannabinoids in hemp.

AhABI4s Negatively Regulate Salt-Stress Response in Peanut.

Soil salinity is one of the major factors that limit the area of cultivable land and yield potential of crops. The ability of salt tolerance varies with plant species. Peanut (Arachis hypogaea L.) is a moderately salt-sensitive and economically important crop, however, their biological processes involved in salt-stress response remain unclear. In this study, we investigated the role of A. hypogaea L. ABSCISIC ACID INSENSITIVE 4s (AhABI4s) in salt tolerance and elucidated its mode of action in peanuts. The results showed that the downregulation of AhABI4s via whole plant virus-induced gene silencing has enhanced the survival rate, biomass accumulation, and root/shoot ratio of peanut seedlings in response to salt-stress. Transcriptomics, quantitative proteomics, and phosphoproteomic analyses were performed using AhABI4s-silenced and Mock plants. The expression pattern of 15,247 genes, 1,900 proteins, and 2,620 phosphorylation sites were affected by silencing of AhABI4s in peanut leaf and root after sodium chloride (NaCl) treatment. Among them, 63 potential downstream target genes of ABI4 changed consistently at both transcription and translation levels, and the protein/phosphorylation levels of 31 ion transporters/channels were also affected. Electrophoretic mobility shift assays (EMSA) showed that ABI4 was able to bind to the promoters of HSP70, fructokinase (FRK), and pyruvate kinase (PK) coding genes in vitro. In addition, we also detected a binding preference of AhABI4 for CACT(G/T)GCA motif in the promoters of down-regulated genes in peanut leaf. Collectively, the potential downstream targets which were regulated at the levels of transcription and translation, binding preference, and in vivo phosphorylation sites that had been revealed in this study will provide new insight into the AhABI4s-mediated salt tolerance regulation mechanism in peanuts.

Fungal phytopathogen modulates plant and insect responses to promote its dissemination

Vector-borne plant pathogens often change host traits to manipulate vector behavior in a way that favors their spread. By contrast, infection by opportunistic fungi does not depend on vectors, although damage caused by an herbivore may facilitate infection. Manipulation of hosts and vectors, such as insect herbivores, has not been demonstrated in interactions with fungal pathogens. Herein, we establish a new paradigm for the plant-insect-fungus association in sugarcane. It has long been assumed that Fusarium verticillioides is an opportunistic fungus, where it takes advantage of the openings left by Diatraea saccharalis caterpillar attack to infect the plant. In this work, we show that volatile emissions from F. verticillioides attract D. saccharalis caterpillars. Once they become adults, the fungus is transmitted vertically to their offspring, which continues the cycle by inoculating the fungus into healthy plants. Females not carrying the fungus prefer to lay their eggs on fungus-infected plants than mock plants, while females carrying the fungus prefer to lay their eggs on mock plants than fungus-infected plants. Even though the fungus impacts D. saccharalis sex behavior, larval weight and reproduction rate, most individuals complete their development. Our data demonstrate that the fungus manipulates both the host plant and insect herbivore across life cycle to promote its infection and dissemination.

OsWRKY93 Dually Functions Between Leaf Senescence and in Response to Biotic Stress in Rice.

Cross talking between natural senescence and cell death in response to pathogen attack is an interesting topic; however, its action mechanism is kept open. In this study, 33 OsWRKY genes were obtained by screening with leaf aging procedure through RNA-seq dataset, and 11 of them were confirmed a significant altered expression level in the flag leaves during aging by using the reverse transcript quantitative PCR (RT-qPCR). Among them, the OsWRKY2, OsWRKY14, OsWRKY26, OsWRKY69, and OsWRKY93 members exhibited short-term alteration in transcriptional levels in response to Magnaporthe grisea infection. The CRISPR/Cas9-edited mutants of five genes were developed and confirmed, and a significant sensitivity to M. oryzae infection was observed in CRISPR OsWRKY93-edited lines; on the other hand, a significant resistance to M. oryzae infection was shown in the enhanced expression OsWRKY93 plants compared to mock plants; however, enhanced expression of other four genes have no significant affection. Interestingly, ROS accumulation was also increased in OsWRKY93 enhanced plants after flg22 treatment, compared with the controls, suggesting that OsWRKY93 is involved in PAMP-triggered immune response in rice. It indicated that OsWRKY93 was involved in both flag leaf senescence and in response to fungi attack.

Apple latent spherical virus (ALSV)-induced gene silencing in a medicinal plant, Lithospermum erythrorhizon

Lithospermum erythrorhizon is a medicinal plant that produces shikonin, a red lipophilic naphthoquinone derivative that accumulates exclusively in roots. The biosynthetic steps required to complete the naphthalene ring of shikonin and its mechanism of secretion remain unclear. Multiple omics studies identified several candidate genes involved in shikonin production. The functions of these genes can be evaluated using virus-induced gene silencing (VIGS) systems, which have been shown advantageous in introducing iRNA genes into non-model plants. This study describes the development of a VIGS system using an apple latent spherical virus (ALSV) vector and a target gene, phytoene desaturase (LePDS1). Virus particles packaged in Nicotiana benthamiana were inoculated into L. erythrorhizon seedlings, yielding new leaves with albino phenotype but without disease symptoms. The levels of LePDS1 mRNAs were significantly lower in the albino plants than in mock control or escape plants. Virus-derived mRNA was detected in infected plants but not in escape and mock plants. Quantitative PCR and deep sequencing analysis indicated that transcription of another hypothetical PDS gene (LePDS2) also decreased in the defective leaves. Virus infection, however, had no effect on shikonin production. These results suggest that virus-based genetic transformation and the VIGS system silence target genes in soil-grown L. erythrorhizon.

Proteomics analysis reveals the defense priming effect of chitosan oligosaccharides in Arabidopsis-Pst DC3000 interaction

Chitosan oligosaccharides (COS) worked effectively in multiple plant-pathogen interactions as plant immunity regulator, however, due to the complexity of the COS-induced immune signaling network, the topic requires further investigation. In the present study, quantitative analysis of proteins was performed to investigate the underlying mechanism of COS induced resistance to Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) in Arabidopsis thaliana. 4303 proteins were successfully quantified, 186, 217 and 207 proteins were differently regulated in mock + Pst, COS, and COS + Pst treated plants, respectively, compared with mock plants. From detailed functional and hierarchical clustering analysis, a priming effect of COS on plant immune system by pre-regulated the key proteins related to signaling transduction, defense response, cell wall biosynthesis and modification, plant growth and development, gene transcription and translation, which confers enhanced resistance when Pst DC3000 infection in Arabidopsis. Moreover, RACK1B which has the potential to be the key kinase receptor for COS signals was found out by protein-protein interaction network analysis of COS responsive proteins. In conclusion, COS treatment enable plant to fine-tuning its defense mechanisms for a more rapid and stronger response to future pathogen attacks, which obviously enhances plants defensive capacity that makes COS worked effectively in multiple plant-pathogen interactions.

Direct and indirect resistance of sugarcane to Diatraea saccharalis induced by jasmonic acid.

Treating plants with synthetic jasmonic acid (JA) induces a defensive response similar to herbivore attack, and is a potential strategy for integrated pest management. Despite the importance of sugarcane, its JA-induced defences have not yet been studied. We investigated the effects of JA treatment on the direct and indirect resistance of sugarcane to the key-pest and specialist herbivore Diatraea saccharalis and the generalist Spodoptera frugiperda. Indirect defences were examined by testing the attraction of Cotesia flavipes, a sugarcane-borer parasitoid, to JA-induced volatile. The results showed that JA-treated sugarcane did not affect the weight gain of the two larvae. However, in dual-choice assays, both species preferred to feed on mock rather than JA-treated plants. Leaf colorimetric analyses showed that visual cues are unlikely to be involved in larval preference, whereas results from olfactometric assays revealed that D. saccharalis preferred JA-induced over mock plant volatiles. After 48 h of treatment, JA-treated plants emitted a volatile blend attractive to C. flavipes, comprised mainly of sesquiterpenes. However, the parasitoid did not discriminate JA-treated from host-damaged plant volatiles. When the wasps were given a choice between JA-treated and JA-treated + host-damaged plants, they preferred the latter, which emitted a more complex blend, suggesting that JA treatment likely does not hamper host-finding. We concluded that JA induces the emission of volatiles that are attractive to the sugarcane borer parasitoid, as well as an antixenosis type of resistance in sugarcane against the two pests, although neither volatiles nor visual cues alone are involved in the underlying mechanism.

Identification and characterization of genes associated with thermo-tolerance using virus induced gene silencing in Nicotiana benthamiana

Crop acclimatization to elevated temperature conditions often demands transcriptional reprogramming of an array of genes to evoke protection from heat stress. Previously, we addressed such question in potato and identified GLP1 (Germin-like protein 1), nsLTP (Non specific lipid transfer protein), PI-PLC (phosphoinositide-specific phospholipase-c), CHP (Conserved hypothetical protein) and RPL4 (60 S Ribosomal L4/L1 protein) as candidate thermo-tolerant genes. Herein, Nicotiana benthamiana knockdown lines were developed to study their functional relevance in high-temperature stress using virus induced gene silencing (VIGS). Among all the VIGS lines tested, silencing of GLP1 and CHP showed significant reduction (more than 75 %) in their endogenous transcript levels, whereas the expression of nsLTP, PI-PLC and RPL4 was reduced by 50 %. Thus suggesting the silencing of endogenous target gene was successful using VIGS. Among those genes tested, VIGS knockdown lines generated against GLP1 and nsLTP produced a very strong hypersensitive phenotype under gradual heat stress and sudden heat shock conditions. Knockdown of GLP1 and nsLTP also showed higher chlorophyll degradation and less cell viability upon stress compared with mock plants. Interestingly, down-regulation of PI-PLC plants showed thermo-sensitive to sudden heat shock, whereas CHP and RPL4 silenced plants showed relatively less sensitive phenotypes. Most importantly, silencing of GLP1 and nsLTP genes compromised acclimation induced H2O2 accumulation, which subsequently failed to activate reactive oxygen species (ROS) scavenging signaling pathways that controlling transcription of antioxidant and other heat stress related genes. These data suggest that GLP1 or nsLTP dependent H2O2 production is required for acquiring thermo-tolerance mediated via activation of ROS-related genes. These analyses will aid in an effort to engineer broad spectrum thermo-tolerance in economically important crop.

A high-throughput belowground plant diversity assay using next-generation sequencing of the trnL intron

We refine and test a next-generation sequencing assay for the molecular identification and quantification of plant roots from mixed-species samples. We modified primers targeting the trnL intron to provide greater taxonomic resolution and developed an improved bioinformatics pipeline that can identify roots based on global, site-, and plot-specific taxon lists. We tested our primers and pipeline on mock plant communities of known composition and mixed-species samples of roots collected from temperate grassland and high Arctic tundra communities. We retrieved a high correlation (0.72) between observed and expected community dissimilarities. We found positive linear relationships between aboveground and belowground species richness in the grassland community, with higher correlations for plot-specific reference databases (R = 0.70) than a global reference database (R = 0.48). This highlights the importance of local reference databases within the bioinformatics pipeline. Lower root than aboveground richness suggests that typical root lateral spread in this grassland is less than 25 cm. We observed lateral rooting extents of up to 40 cm and rooting depths of up to 30 cm for six high Arctic species. Testing on mock community, grassland, and tundra samples demonstrated that next-generation sequencing using our improved trnL primers and pipeline can successfully recover plant root community structure.

The effects of rice seed dressing with Paenibacillus yonginensis and silicon on crop development on South Korea’s reclaimed tidal land

A field trial to investigate the effects of plant growth promoting bacteria (PGPB) Paenibacillus yonginensis (DCY84T) and/or SiO2 seed coating on rice growth (Oryza sativa L.) was carried out on reclaimed tidal land in Taean County in South Korea. The field test was performed twice between May–October 2014 and May–October 2015, in a randomized complete block (RCB) design with three replications. Treatments consisted of: Mock, DCY84T-treated seeds, SiO2-coated seeds and DCY84T-SiO2-treated seeds and each treatment area covered approximately 300m2. During the early developmental period of rice seedlings, the SiO2 coating without DCY84T led to the most favorable 30 DAS rice seedling parameters. Moreover, the combination of DCY84T and SiO2 treatments resulted in 2-fold greater fresh and dry weights of 60 DAS rice seedlings compared to Mock seedlings. DCY84T and SiO2, both individually and together, produced a greater grain yield and a greater total yield; specifically, DCY84T and SiO2 treatments yielded a 73% and 70% increase in mass compared to Mock plants, respectively. Rice treated with both DCY84T and SiO2 treatment contained the highest amount of Al, Fe, Ca and Mg, which were 54%, 169%, 42% and 67% higher than the Mock rice, respectively. Remarkably, DCY84T treatment had the most phosphate [P], potassium [K] and total nitrogen [T–N]. DCY84T and/or SiO2 treatment highly increased the whole kernel percentage. Thus, lower its broken kernel percentage to 9.60–24.58%. The protein content of the grain with both treatments was 7.2%, which was greater than that of the Mock grain (6.0%). The content of chlorophyll a, b and carotinoid in the rice leaves which were treated with silica and DCY84 has increased more than the mock without treatment. After harvest, the GABA content of brown rice was increased to 1.9-fold (2014), 1.5 fold (2015) compared to mock grain, respectively. Overall, DCY84T treatment and SiO2 coating can be useful methods for promoting growth of rice under conditions of saline stress. Results from other laboratory trials and greenhouse experiments are also provided.

Bacillus subtilis QST 713 Confers Protection to Tomato Plants Against Pseudomonas syringae pv tomato and Induces Plant Defence‐related Genes

AbstractBacterial speck, caused by Pseudomonas syringae pv. tomato (Pst), is an economically important disease of tomato, resulting in yield loss of marketable fruit. Management of bacterial speck is a challenge in commercial production fields due to the limited efficacy of current disease management strategies, as the pathogen acquires resistance to antibiotics and fixed copper bactericides and host resistance has not proven durable. Therefore, it is essential to develop alternative disease management strategies, like biological control. In this study, the efficacy of the commercially available biocontrol agent Bacillus subtilis QST 713 along with copper hydroxide was tested against Pst under greenhouse conditions. QST 713 reduced significantly disease severity and incidence compared to control and the copper hydroxide treatment; subsequently, the Pst population was lower in the QST 713‐treated plants compared to control. In parallel, QST 713 and copper hydroxide increased plant height compared to control and mock plants. Furthermore, the quantitative PCR analysis of PR1a, PR1b and Pin2 expression suggests a positive role for Pin2 in the plant protective activity of QST 713, as Pin2 expression was significantly higher in the QST 713‐treated plants challenged with Pst compared to the control Pst‐inoculated plants.