Transcriptomic Analysis of the Response of the Dioryctria abietella Larva Midgut to Bacillus thuringiensis 2913 Infection.

Dioryctria abietella Denis Schiffermuller (Lepidoptera: Pyralidae) is an oligophagous pest that mainly damages Pinaceae plants. Here, we investigated the effects of the Bacillus thuringiensis 2913 strain (Bt 2913), which carries the Cry1Ac, Cry2Ab, and Vip3Aa genes, on the D. abietella midgut transcriptome at 6, 12, and 24 h after infection. In total, 7497 differentially expressed genes (DEGs) were identified from the midgut transcriptome of D. abietella larvae infected with Bt 2913. Among these DEGs, we identified genes possibly involved in Bt 2913-induced perforation of the larval midgut. For example, the DEGs included 67 genes encoding midgut proteases involved in Cry/Vip toxin activation, 74 genes encoding potential receptor proteins that bind to insecticidal proteins, and 19 genes encoding receptor NADH dehydrogenases that may bind to Cry1Ac. Among the three transcriptomes, 88 genes related to metabolic detoxification and 98 genes related to immune defense against Bt 2913 infection were identified. Interestingly, 145 genes related to the 60S ribosomal protein were among the DEGs identified in the three transcriptomes. Furthermore, we performed bioinformatic analysis of zonadhesin, GST, CYP450, and CarE in the D. abietella midgut to determine their possible associations with Bt 2913. On the basis of the results of this analysis, we speculated that trypsin and other serine proteases in the D. abietella larval midgut began to activate Cry/Vip prototoxin at 6 h to 12 h after Bt 2913 ingestion. At 12 h after Bt 2913 ingestion, chymotrypsin was potentially involved in degrading the active core fragment of Vip3Aa toxin, and the detoxification enzymes in the larvae contributed to the metabolic detoxification of the Bt toxin. The ABC transporter and several other receptor-protein-related genes were also downregulated to increase resistance to Bt 2913. However, the upregulation of 60S ribosomal protein and heat shock protein expression weakened the resistance of larvae to Bt 2913, thereby enhancing the expression of NADH dehydrogenase and other receptor proteins that are highly expressed in the larval midgut and bind to activating toxins, including Cry1Ac. At 24 h after Bt 2913 ingestion, many activated toxins were bound to receptor proteins such as APN in the larval midgut, resulting in membrane perforation. Here, we clarified the mechanism of Bt 2913 infection in D. abietella larvae, as well as the larval immune defense response to Bt 2913, which provides a theoretical basis for the subsequent control of D. abietella using B. thuringiensis.

Preparation of pH-Responsive Kas@ZnO Quantum Dots for Synergistic Control of Rice Blast and Enhanced Disease Resistance in Rice.

The construction of controlled-release formulations improves the sustained-release performance and utilization efficiency of pesticides, which are important aspects in plant protection and environmental chemistry. The current study employs kasugamycin (Kas), which is widely used to control Magnaporthe oryzae, conjugated with carboxyl-functionalized ZnO quantum dots via amide linkages to yield a pH-responsive pesticide delivery system (Kas@ZnO). Physicochemical characterizations indicated the successful preparation of the Kas@ZnO nanoparticles. In vitro drug release assessments indicated that Kas@ZnO exhibited a loading capacity of 21.05% and could effect the controlled release of Kas in an acidic environment, which is beneficial given the unique acidic microenvironment of M. oryzae. Bioactivity assays demonstrated that Kas@ZnO could simultaneously inhibit mycelial growth and spore germination. Additionally, bioactivity tests showed that the control efficacy of Kas@ZnO against rice blast reached 67.43% after 14 days of in vivo spray inoculation, which was higher than that obtained with Kas (55.50%), suggesting improved beneficial effects of Kas@ZnO application over a prolonged duration. Moreover, Kas@ZnO enhanced the activity of defense-related enzymes in rice and upregulated the expression of defense-related genes, such as OsPR2, OsPR3, OsPR5, OsWRKY45, OsLYP6, and OsNAC4. Ultimately, the biosafety assessments revealed that Kas@ZnO did not exert any harmful effects on rice and demonstrated slight toxicity toward zebrafish. These findings indicate that Kas@ZnO can function as a pH-sensitive pesticide delivery system, allowing for targeted release of the pesticide within plant tissues. This technology demonstrates significant potential for eco-friendly plant disease management.

CaARP1/CaSGT1 Module Regulates Vegetative Growth and Defense Response of Pepper Plants against Phytophthora capsici.

Pepper (Capsicum annuum L.) suffers severe quality and yield loss from oomycete diseases caused by Phytophthora capsici. CaSGT1 was previously determined to positively regulate the immune response of pepper plants against P. capsici, but by which mechanism remains elusive. In the present study, the potential interacting proteins of CaSGT1 were isolated from pepper using a yeast two-hybrid system, among which CaARP1 was determined to interact with CaSGT1 via bimolecular fluorescence complementation (BiFC) and microscale thermophoresis (MST) assays. CaARP1 belongs to the auxin-repressed protein family, which is well-known to function in modulating plant growth. The transcriptional and protein levels of CaARP1 were both significantly induced by infection with P. capsici. Silencing of CaARP1 promotes the vegetative growth of pepper plants and attenuates its disease resistance to P. capsici, as well as compromising the hypersensitive response-like cell death in pepper leaves induced by PcINF1, a well-characterized typical PAMP from P. capsici. Chitin-induced transient expression of CaARP1 in pepper leaves enhanced its disease resistance to P. capsici, which is amplified by CaSGT1 co-expression as a positive regulator. Taken together, our result revealed that CaARP1 plays a dual role in the pepper, negatively regulating the vegetative growth and positively regulating plant immunity against P. capsici in a manner associated with CaSGT1.

Genome-Wide Transcriptional Response of Avocado to Fusarium sp. Infection.

The avocado crop is relevant for its economic importance and because of its unique evolutionary history. However, there is a lack of information regarding the molecular processes during the defense response against fungal pathogens. Therefore, using a genome-wide approach in this work, we investigated the transcriptional response of the Mexican horticultural race of avocado (Persea americana var. drymifolia), including miRNAs profile and their possible targets. For that, we established an avocado-Fusarium hydroponic pathosystem and studied the response for 21 days. To guarantee robustness in the analysis, first, we improved the avocado genome assembly available for this variety, resulting in 822.49 Mbp in length with 36,200 gene models. Then, using an RNA-seq approach, we identified 13,778 genes differentially expressed in response to the Fusarium infection. According to their expression profile across time, these genes can be clustered into six groups, each associated with specific biological processes. Regarding non-coding RNAs, 8 of the 57 mature miRNAs identified in the avocado genome are responsive to infection caused by Fusarium, and the analysis revealed a total of 569 target genes whose transcript could be post-transcriptionally regulated. This study represents the first research in avocados to comprehensively explore the role of miRNAs in orchestrating defense responses against Fusarium spp. Also, this work provides valuable data about the genes involved in the intricate response of the avocado during fungal infection.

Improving transient expression in N. benthamiana by suppression of the Nb-SABP2 and Nb-COI1 plant defence response related genes.

Currently transient expression is one of the preferred plant-based technologies for recombinant protein manufacturing, particularly in respect to pharmaceutically relevant products. Modern hybrid transient expression systems combine the features of Agrobacterium tumefaciens and viral vectors. However, host plant reaction to Agrobacterium-mediated delivery of gene of interest can negatively affect foreign protein accumulation. In this study, we investigated whether the modulation of plant immune response through knockdown of the Nb-SABP2 and Nb-COI1 N. benthamiana genes could improve recombinant protein yield. In plants, the SABP2 and COI1 proteins are involved in the salicylic acid and jasmonic acid metabolism, respectively. We exemplified the utility of this approach with the green fluorescence (GFP) and ß nerve growth factor (ßNGF) proteins: compared to the tobacco mosaic virus (TMV)-based vector the Nb-SABP2 and Nb-COI1-suppressed plants provided an increased recombinant protein accumulation. We also show that this strategy is extendable to the expression systems utilizing potato virus X (PVX) as the vector backbone: the enhanced amounts of ßNGF were detected in the Nb-SABP2 and Nb-COI1-depleted leaves co-infiltrated with the PVX-ßNGF. These findings suggest that modulating host plant reaction to agrodelivery of expression vectors could be useful for improving transient foreign protein production in N. benthamiana.

Comparative transcriptome analysis reveals defense responses against soft rot induced by Pectobacterium aroidearum and Pectobacterium carotovorum in Pinellia ternata.

Pectobacterium carotovorum and Pectobacterium aroidearum represent the primary pathogens causing variable soft rot disease. However, the fundamental defense responses of Pinellia ternata to pathogens remain unclear. Our investigation demonstrated that the disease produced by P. carotovorum is more serious than P. aroidearum. RNA-seq analysis indicated that many cell wall-related genes, receptor-like kinase genes, and resistance-related genes were induced by P. aroidearum and P. carotovorum similarly. But many different regulatory pathways exert a crucial function in plant immunity against P. aroidearum and P. carotovorum, including hormone signaling, whereas more auxin-responsive genes were responsive to P. carotovorum, while more ethylene and gibberellin-responsive genes were responsive to P. aroidearum. 12 GDSL esterase/lipase genes and 3 fasciclin-like arabinogalactan protein genes were specifically upregulated by P. carotovorum, whereas 11 receptor-like kinase genes and 8 disease resistance genes were up-regulated only by P. aroidearum. Among them, a lectin gene (part1transcript/39001) was induced by P. carotovorum and P. aroidearum simultaneously. Transient expression in N. benthamiana demonstrated that the lectin gene improves plant resistance to P. carotovorum. This study offers a comprehensive perspective on P. ternata immunity produced by different soft rot pathogens and reveals the importance of lectin in anti-soft rot of P. ternata for the first time.

Defense Responses Induced by Viral Movement Protein and Its Nuclear Localization Modulate Virus Cell-to-Cell Transport.

Movement proteins (MPs) encoded by plant viruses are essential for cell-to-cell transport of viral genomes through plasmodesmata. The genome of hibiscus green spot virus contains a module of two MP genes termed 'binary movement block' (BMB), encoding the proteins BMB1 and BMB2. Here, BMB1 is shown to induce a defense response in Nicotiana benthamiana plants that inhibits BMB-dependent virus transport. This response is characterized by the accumulation of reactive oxygen species, callose deposition in the cell wall, and upregulation of 9-LOX expression. However, the BMB1-induced response is inhibited by coexpression with BMB2. Furthermore, BMB1 is found to localize to subnuclear structures, in particular to Cajal bodies, in addition to the cytoplasm. As shown in experiments with a BMB1 mutant, the localization of BMB1 to nuclear substructures enhances BMB-dependent virus transport. Thus, the virus transport mediated by BMB proteins is modulated by (i) a BMB1-induced defense response that inhibits transport, (ii) suppression of the BMB1-induced response by BMB2, and (iii) the nuclear localization of BMB1 that promotes virus transport. Collectively, the data presented demonstrate multiple levels of interactions between viral pathogens and their plant hosts during virus cell-to-cell transport.

Comparative transcriptome analysis reveals the differences in wound-induced agarwood formation between Chi-Nan and ordinary germplasm of Aquilaria sinensis.

Agarwood is a rare and valuable heartwood derived from Aquilaria sinensis in China. Compared with ordinary germplasm, Chi-Nan, a special germplasm of A. sinensis, has a better agarwood-producing capacity. However, the mechanisms underlying their different qualities remain poorly characterized. Here, a comparative transcriptome analysis of Chi-Nan and ordinary A. sinensis was carried out to investigate the wound responses of both germplasms. A total of 198.19 Gb of clean data were obtained with an average of 6.61 Gb of clean reads for each sample. By comparing with their control groups, more differentially expressed genes (DEGs) were observed in Chi-Nan germplasm. Kyoto Encyclopedia of Genes and Genomes (KEGG) and expression profile analysis suggested that Chi-Nan possesses a stronger ability to respond to wounding. Furthermore, the enrichment of biosynthetic pathways related to sesquiterpenes and 2-(2-phenylethyl) chromones (PECs) were more significant in Chi-Nan than in ordinary germplasm, and related genes showed significantly higher up-regulation in Chi-Nan after wounding. Sixteen candidate genes presumably involved in biosynthesis of agarwood components were identified and found to exhibit higher up-regulation in Chi-Nan than in ordinary germplasm in response to wounding. Overall, these results are helpful in explaining reasons for the higher agarwood-producing properties of Chi-Nan, and contribute to a further understanding of the mechanism of agarwood formation in A. sinensis.

Neuronal mechanism of innate rapid processing of threating animacy cue in primates: insights from the neuronal responses to snake images.

To survive in nature, it is crucial for animals to promptly and appropriately respond to visual information, specifically to animacy cues that pose a threat. The subcortical visual pathway is thought to be implicated in the processing of visual information necessary for these responses. In primates, this pathway consists of retina-superior colliculus-pulvinar-amygdala, functioning as a visual pathway that bypasses the geniculo-striate system (retina-lateral geniculate nucleus-primary visual cortex). In this mini review, we summarize recent neurophysiological studies that have revealed neural responses to threatening animacy cues, namely snake images, in different parts of the subcortical visual pathway and closely related brain regions in primates. The results of these studies provide new insights on (1) the role of the subcortical visual pathway in innate cognitive mechanisms for predator recognition that are evolutionarily conserved, and (2) the possible role of the medial prefrontal cortex (mPFC) and anterior cingulate cortex (ACC) in the development of fear conditioning to cues that should be instinctively avoided based on signals from the subcortical visual pathway, as well as their function in excessive aversive responses to animacy cues observed in conditions such as ophidiophobia (snake phobia).

Cultivation of Fungal Endophytes with Tissue Culture Grapevine Seedlings Reprograms Metabolism by Triggering Defence Responses.

In this study, the transcriptome profiles of tissue-cultured grapevine (Vitis vinifera L. × Vitis labrusca L.: Rose Honey) seedlings inoculated with fungal endophytes Epicoccum layuense R2-21 (Epi R2-21) and Alternaria alternata XHYN2 (Alt XHYN2), were analyzed at three different time points (6 h, 6 d, and 15 d). A total of 4783 differentially expressed genes (DEGs) was found, of which 1853 (6 h), 3878 (6 d), and 4732 (15 d) were differentially expressed relative to those of the control in endophyte Epi R2-21 treatments, while a total of 5898 DEGs, of which 2726 (6 h), 4610 (6 d), and 3938 (15 d) were differentially expressed in endophyte Alt XHYN2 treatments. DEGs enriched in secondary metabolic pathways, plant-pathogen interaction, and hormone signalling were further analysed. The upregulated DEGs in the Epi R2-21 and Alt XHYN2 treatments, both enriched in the Kyoto Encyclopedia of Genes and Genomes (KEGG), were mainly involved in flavonoid biosynthesis, phenylpropanoid biosynthesis, stilbenoid, diarylheptanoid and gingerol biosynthesis, phenylalanine metabolism, and circadian rhythms-plant and plant-pathogen interactions, similar to the trend observed in our previous study conducted on the cultivar 'Cabernet Sauvignon' (Vitis vinifera L.). Taken together with the results obtained from the cultivar 'Cabernet Sauvignon', it was found that tissue-cultured seedlings of the cultivar 'Rose Honey' induced a stronger defence response to fungal endophyte infection than that of the cultivar 'Cabernet Sauvignon', and inoculation with the endophyte Alt XHYN2 triggered a stronger response than inoculation with the endophyte Epi R2-21. In addition, the protein-protein interaction (PPI) network revealed that the genes VIT_16s0100g00910, encoding CHS, and VIT_11s0065g00350, encoding CYP73A, were involved in secondary metabolism and thus mediated in the resistance mechanism of grapevine on both the cultivars. The results showed that inoculation with the endophytes Epi R2-21 and Alt XHYN2 had a great ability to induce defence responses and reprogram the gene expression profiles in different grapevine cultivars, which deepens our knowledge of the interaction between fungal endophytes and grapevine and gives hints for grape quality management in viticulture using candidate fungal endophytes.

Oral secretions from striped stem borer (Chilo suppressalis) induce defenses in rice.

BACKGROUND: The striped stem borer (SSB, Chilo suppressalis) is one of the most destructive insect pests on rice. As a chewing insect, SSB larval feeding causes a dramatic increase in rice defense responses. However, the effects of oral secretions (OSs) during SSB feeding on rice defense remain largely unexplored. RESULTS: In this study, based on transcriptome analysis results, treatment with SSB OSs regulated the expression of genes involved in the plant defense-related pathways of calcium, mitogen-activated protein kinases, reactive oxygen species, jasmonic acid (JA), herbivore-induced plant volatiles (HIPVs), and protease inhibitors. Unsurprisingly, treatment with SSB OSs elicited the accumulation of JA and JA-isoleucine in rice. The defense mechanisms activated by the cascade not only induced the expression of trypsin inhibitors, inhibiting the normal growth of SSB larvae but also induced HIPVs emission, rendering rice attractive to a common larval parasitoid. High-throughput proteome sequencing of SSB OSs led to 534 proteins being identified and 343 proteins with two or more unique peptides being detected. CONCLUSION: The study demonstrates that SSB OSs trigger both direct and indirect defense mechanisms in rice, akin to the effects of SSB feeding. It identifies specific proteins in SSB OSs that may influence the interactions between SSB and rice during feeding, providing valuable insights for effectors research. © 2024 Society of Chemical Industry.

New insights into azelaic acid-induced resistance against Alternaria Solani in tomato plants.

BACKGROUND: The effect of azelaic acid (Aza) on the response of tomato plants to Alternaria solani was investigated in this study. After being treated with Aza, tomato plants were infected with A. solani, and their antioxidant, biochemical, and molecular responses were analyzed. RESULTS: The results demonstrated that H2O2 and MDA accumulation increased in control plants after pathogen infection. Aza-treated plants exhibited a remarkable rise in peroxidase (POD) and catalase (CAT) activities during the initial stages of A. solani infection. Gene expression analysis revealed that both Aza treatment and pathogen infection altered the expression patterns of the SlNPR1, SlERF2, SlPR1, and SlPDF1.2 genes. The expression of SlPDF1.2, a marker gene for the jasmonic acid/ethylene (JA/ET) signaling pathway, showed a remarkable increase of 4.2-fold upon pathogen infection. In contrast, for the SlNPR1, a key gene in salicylic acid (SA) pathway, this increased expression was recorded with a delay at 96 hpi. Also, the phytohormone analysis showed significantly increased SA accumulation in plant tissues with disease development. It was also revealed that tissue accumulation of JA in Aza-treated plants was increased following pathogen infection, while it was not increased in plants without pathogen inoculation. CONCLUSION: The results suggest that the resistance induced by Aza is mainly a result of modulations in both SA and JA pathways following complex antioxidant and molecular defense responses in tomato plants during A. solani infection. These findings provide novel information regarding inducing mechanisms of azelaic acid which would add to the current body of knowledge of SAR induction in plants as result of Aza application.

Toxic effect of fluorene on Perinereis aibuhitensis body wall and its corresponding defense mechanisms: A metabolomics perspective.

Fluorene is a coastal sediment pollutant with high ecological risk. Perinereis aibuhitensis is an ecotoxicological model used for polycyclic aromatic hydrocarbon bioremediation; however, the effects of fluorene on the physiological metabolism of P. aibuhitensis and its corresponding responses remain unclear. This study explored the tolerance and defense responses of P. aibuhitensis in sediments with different fluorene concentrations using histology, ecological biomarkers, and metabolic responses. Metabolomics analyses revealed that P. aibuhitensis has high tolerance to fluorene in sediments. Fluorene stress disrupted the normal metabolism of the P. aibuhitensis body wall, resulting in excessive glycosphospholipid and stearamide accumulation and elevated oxygen consumption rates. To mitigate this, P. aibuhitensis has adopted tail cutting, yellowing, and modulation of metabolite contents in the body wall. This study provides novel insights into the potential ecological risk of fluorene pollution in marine sediments and proposes the use of P. aibuhitensis in the bioremediation of fluorene-contaminated sediments.

A delayed response in phytohormone signaling and production contributes to pine susceptibility to Fusarium circinatum.

BACKGROUND: Fusarium circinatum is the causal agent of pine pitch canker disease, which affects Pinus species worldwide, causing significant economic and ecological losses. In Spain, two Pinus species are most affected by the pathogen; Pinus radiata is highly susceptible, while Pinus pinaster has shown moderate resistance. In F. circinatum-Pinus interactions, phytohormones are known to play a crucial role in plant defense. By comparing species with different degrees of susceptibility, we aimed to elucidate the fundamental mechanisms underlying resistance to the pathogen. For this purpose, we used an integrative approach by combining gene expression and metabolomic phytohormone analyses at 5 and 10 days post inoculation. RESULTS: Gene expression and metabolite phytohormone contents suggested that the moderate resistance of P. pinaster to F. circinatum is determined by the induction of phytohormone signaling and hormone rearrangement beginning at 5 dpi, when symptoms are still not visible. Jasmonic acid was the hormone that showed the greatest increase by 5 dpi, together with the active gibberellic acid 4 and the cytokinin dehydrozeatin; there was also an increase in abscisic acid and salicylic acid by 10 dpi. In contrast, P. radiata hormonal changes were delayed until 10 dpi, when symptoms were already visible; however, this increase was not as high as that in P. pinaster. Indeed, in P. radiata, no differences in jasmonic acid or salicylic acid production were found. Gene expression analysis supported the hormonal data, since the activation of genes related to phytohormone synthesis was observed earlier in P. pinaster than in the susceptible P. radiata. CONCLUSIONS: We determine that the moderate resistance of P. pinaster to F. circinatum is in part a result of early and strong activation of plant phytohormone-based defense responses before symptoms become visible. We suggest that jasmonic acid signaling and production are strongly associated with F. circinatum resistance. In contrast, P. radiata susceptibility was attributed to a delayed response to the fungus at the moment when symptoms were visible. Our results contribute to a better understanding of the phytohormone-based defense mechanism involved in the Pinus-F. circinatum interactions and provide insight into the development of new strategies for disease mitigation.

Recent Insights into Salicylic Acid Accumulation: Emerging Molecular Players and Novel Perspectives on Plant Development and Nutrition.

Salicylic acid (SA) is a central phytohormone that orchestrates genetic and physiological responses involving defense mechanisms against pathogens. This review presents cutting-edge research on emerging molecular players identified within the past five years contributing to SA accumulation. Furthermore, we delve into two relatively underexplored domains: the dynamic production of SA throughout the plant life cycle, with a specific focus on senescence, and the intricate interplay between SA, nutrition, and its multifaceted implications on plant development and defense response. This synthesis aims to provide a contemporary and comprehensive understanding of the diverse roles of SA in plant biology.

Stress-related transcriptomic changes associated with GFP transgene expression and active transgene silencing in plants.

Plants respond to biotic and abiotic stress by activating and interacting with multiple defense pathways, allowing for an efficient global defense response. RNA silencing is a conserved mechanism of regulation of gene expression directed by small RNAs important in acquired plant immunity and especially virus and transgene repression. Several RNA silencing pathways in plants are crucial to control developmental processes and provide protection against abiotic and biotic stresses as well as invasive nucleic acids such as viruses and transposable elements. Various notable studies have shed light on the genes, small RNAs, and mechanisms involved in plant RNA silencing. However, published research on the potential interactions between RNA silencing and other plant stress responses is limited. In the present study, we tested the hypothesis that spreading and maintenance of systemic post-transcriptional gene silencing (PTGS) of a GFP transgene are associated with transcriptional changes that pertain to non-RNA silencing-based stress responses. To this end, we analyzed the structure and function of the photosynthetic apparatus and conducted whole transcriptome analysis in a transgenic line of Nicotiana benthamiana that spontaneously initiates transgene silencing, at different stages of systemic GFP-PTGS. In vivo analysis of chlorophyll a fluorescence yield and expression levels of key photosynthetic genes indicates that photosynthetic activity remains unaffected by systemic GFP-PTGS. However, transcriptomic analysis reveals that spreading and maintenance of GFP-PTGS are associated with transcriptional reprogramming of genes that are involved in abiotic stress responses and pattern- or effector-triggered immunity-based stress responses. These findings suggest that systemic PTGS may affect non-RNA-silencing-based defense pathways in N. benthamiana, providing new insights into the complex interplay between different plant stress responses.

Unraveling verticillium wilt resistance: insight from the integration of transcriptome and metabolome in wild eggplant.

Verticillium wilt, caused by Verticillium dahliae, is a soil-borne disease affecting eggplant. Wild eggplant, recognized as an excellent disease-resistant resource against verticillium wilt, plays a pivotal role in grafting and breeding for disease resistance. However, the underlying resistance mechanisms of wild eggplant remain poorly understood. This study compared two wild eggplant varieties, LC-2 (high resistance) and LC-7 (sensitive) at the phenotypic, transcriptomic, and metabolomic levels to determine the molecular basis of their resistance to verticillium wilt. These two varieties exhibit substantial phenotypic differences in petal color, leaf spines, and fruit traits. Following inoculation with V. dahliae, LC-2 demonstrated significantly higher activities of polyphenol oxidase, superoxide dismutase, peroxidase, phenylalanine ammonia lyase, ß-1,3 glucanase, and chitinase than did LC-7. RNA sequencing revealed 4,017 differentially expressed genes (DEGs), with a significant portion implicated in processes associated with disease resistance and growth. These processes encompassed defense responses, cell wall biogenesis, developmental processes, and biosynthesis of spermidine, cinnamic acid, and cutin. A gene co-expression analysis identified 13 transcription factors as hub genes in modules related to plant defense response. Some genes exhibited distinct expression patterns between LC-2 and LC-7, suggesting their crucial roles in responding to infection. Further, metabolome analysis identified 549 differentially accumulated metabolites (DAMs) between LC-2 and LC-7, primarily consisting of compounds such as flavonoids, phenolic acids, lipids, and other metabolites. Integrated transcriptome and metabolome analyses revealed the association of 35 gene-metabolite pairs in modules related to the plant defense response, highlighting the interconnected processes underlying the plant defense response. These findings characterize the molecular basis of LC-2 resistance to verticillium wilt and thus have potential value for future breeding of wilt-resistant eggplant varieties.

Primary Metabolic Response of Aristolochia contorta to Simulated Specialist Herbivory under Elevated CO2 Conditions.

This study explores how elevated carbon dioxide (CO2) levels affects the growth and defense mechanisms of plants. We focused on Aristolochia contorta Bunge (Aristolochiaceae), a wild plant that exhibits growth reduction under elevated CO2 in the previous study. The plant has Sericinus montela Gray (Papilionidae) as a specialist herbivore. By analyzing primary metabolites, understanding both the growth and defense response of plants to herbivory under elevated CO2 conditions is possible. The experiment was conducted across four groups, combining two CO2 concentration conditions (ambient CO2 and elevated CO2) with two herbivory conditions (herbivory treated and untreated). Although many plants exhibit increased growth under elevated CO2 levels, A. contorta exhibited reduced growth with lower height, dry weight, and total leaf area. Under herbivory, A. contorta triggered both localized and systemic responses. More primary metabolites exhibited significant differences due to herbivory treatment in systemic tissue than local leaves that herbivory was directly treated. Herbivory under elevated CO2 level triggered more significant responses in primary metabolites (17 metabolites) than herbivory under ambient CO2 conditions (five metabolites). Several defense-related metabolites exhibited higher concentrations in the roots and lower concentrations in the leaves in response to the herbivory treatment in the elevated CO2 group. This suggests a potential intensification of defensive responses in the underground parts of the plant under elevated CO2 levels. Our findings underscore the importance of considering both abiotic and biotic factors in understanding plant responses to environmental changes. The adaptive strategies of A. contorta suggest a complex response mechanism to elevated CO2 and herbivory pressures.

Transcriptomic Profiling of Sugarcane White Leaf (SCWL) Canes during Maturation Phase.

Sugarcane white leaf (SCWL) disease, caused by Candidatus Phytoplasma sacchari, results in the most damage to sugarcane plantations. Some SCWL canes can grow unnoticed through the maturation phase, subsequently resulting in an overall low sugar yield, or they can be used accidentally as seed canes. In this work, 12-month-old SCWL and asymptomatic canes growing in the same field were investigated. An abundance of phytoplasma in SCWL canes affected growth and sugar content as well as alterations of transcriptomic profiles corresponding to several pathways that responded to the infection. Suppression of photosynthesis, porphyrin and chlorophyll metabolism, coupled with an increase in the expression of chlorophyllase, contributed to the reduction in chlorophyll levels and photosynthesis. Blockage of sucrose transport plausibly occurred due to the expression of sugar transporters in leaves but suppression in stalks, resulting in low sugar content in canes. Increased expression of genes associated with MAPK cascades, plant hormone signaling transduction, callose plug formation, the phenylpropanoid pathway, and calcium cascades positively promoted defense mechanisms against phytoplasma colonization by an accumulation of lignin and calcium in response to plant immunity. Significant downregulation of CPK plausibly results in a reduction in antioxidant enzymes and likely facilitates pathogen invasion, while expression of sesquiterpene biosynthesis possibly attracts the insect vectors for transmission, thereby enabling the spread of phytoplasma. Moreover, downregulation of flavonoid biosynthesis potentially intensifies the symptoms of SCWL upon challenge by phytoplasma. These SCWL sugarcane transcriptomic profiles describe the first comprehensive sugarcane-phytoplasma interaction during the harvesting stage. Understanding molecular mechanisms will allow for sustainable management and the prevention of SCWL disease-a crucial benefit to the sugar industry.

Integrated Transcriptome and Metabolome Analysis Reveals Molecular Mechanisms Underlying Resistance to Phytophthora Root Rot.

Soybean production is significantly impacted by Phytophthora root rot (PRR), which is caused by Phytophthora sojae. The nucleotide-binding leucine-rich repeat (NLR) gene family plays a crucial role in plant disease resistance. However, current understanding of the function of soybean NLR genes in resistance to PRR is limited. To address this knowledge gap, transgenic soybean plants overexpressing the NLR gene (Glyma.18g283200) were generated to elucidate the molecular mechanism of resistance. Here, transcript changes and metabolic differences were investigated at three time points (12, 24, and 36 h) after P. sojae infection in hypocotyls of two soybean lines, Dongnong 50 (susceptible line, WT) and Glyma.18g283200 overexpression line (resistant line, OE). Based on the changes in differentially expressed genes (DEGs) in response to P. sojae infection in different lines and at different time points, it was speculated that HOPZ-ACTIVATED RESISTANCE 1 (ZAR1), valine, leucine, and isoleucine degradation, and phytohormone signaling may be involved in the defense response of soybean to P. sojae at the transcriptome level by GO term and KEGG pathway enrichment analysis. Differentially accumulated metabolites (DAMs) analysis revealed that a total of 223 and 210 differential metabolites were identified in the positive ion (POS) and negative ion (NEG) modes, respectively. An integrated pathway-level analysis of transcriptomics (obtained by RNA-seq) and metabolomics data revealed that isoflavone biosynthesis was associated with disease resistance. This work provides valuable insights that can be used in breeding programs aiming to enhance soybean resistance against PRR.