Deyi Yu

Corn stalk rot (CSR) is a devastating soil-borne disease, but the transcriptional basis of constitutive resistance remains unclear. Here, we performed comparative transcriptome analysis of the CSR-resistant maize cultivar Qi319 (JR) and the CSR-susceptible maize cultivar Ye478 (JS) under pathogen-challenged conditions. A total of 6009 differentially expressed genes (DEGs) (3074 upregulated, 2935 downregulated in JR) were identified, with JR exhibiting a higher proportion of low-expression genes. Functional enrichment based on all the DEGs identified significant overrepresentation of flavonoid biosynthesis, Cutin/wax biosynthesis, alpha-linolenic acid metabolism (jasmonic acid synthesis), and starch/sucrose metabolism pathways. Weighted gene co-expression network analysis (WGCNA) identified candidate hub genes, including Zm00001d006069, Zm00001d043607 (hexokinase6), and Zm00001d044122 (anthocyaninless1), potentially associated with regulatory roles. qRT-PCR validated the differential expression of key genes. Subcellular localization assays further showed that Zm00001d044122 (anthocyaninless1) and Zm00001d006069 were mainly localized to the nucleus and plasma membrane, respectively. Collectively, this study provides a transcriptomic landscape associated with CSR resistance and suggests candidate coordinated physical, chemical, hormonal, and metabolic defense pathways. The identified hub genes are candidate targets for marker-assisted selection and genetic improvement. However, pathway-level interpretations are transcriptome-based hypotheses and require metabolite profiling and functional validation.

Southern corn leaf blight (SCLB), caused by Bipolaris maydis, poses a serious threat to maize production worldwide. In our previous study, Bacillus velezensis BV3 was isolated and demonstrated strong antagonistic activity against maize leaf spot pathogens and effective disease control in greenhouse experiments. In this study, we evaluated the plant growth-promoting effects of BV3 on two maize cultivars through root application in pot experiments, and investigated the underlying molecular mechanisms using transcriptomic and metabolomic analyses. Inoculation with BV3 significantly promoted maize growth. Moreover, BV3 treatment induced extensive transcriptional and metabolic reprogramming in maize. Transcriptomic analysis identified numerous differentially expressed genes (DEGs) mainly enriched in plant–pathogen interaction, plant hormone signal transduction, MAPK signaling pathway, and phenylpropanoid biosynthesis pathways. Metabolomic analysis revealed substantial changes in metabolite accumulation, particularly in lipids, amino acids, sugars, organic acids, and polyphenols, with enriched pathways including secondary metabolite biosynthesis, phenylpropanoid biosynthesis, and flavonoid biosynthesis. LC/MS and GC/MS analyses further revealed that BV3 produced diverse bioactive compounds. 2,4-DTBP and surfactin exhibited strong antifungal activities, particularly against B. maydis and Exserohilum turcicum. Overall, Bacillus sp. BV3 exhibits strong biocontrol efficacy against maize leaf spot pathogens and significant plant growth-promoting activity, highlighting its potential as an eco-friendly biocontrol agent for the management of southern corn leaf blight.

The flower thrips, Frankliniella intonsa, is a major pest threatening citrus production. However, chemical control remains the primary management measure, which poses significant risks on ecosystems. Hence, it is urgent to prioritize more eco-friendly measures to efficiently control thrips. The ladybird, Cheilomenes sexmaculata, is a predominant natural enemy in the local citrus agroecosystem and could play a key role in suppressing thrips in agricultural landscapes. Although some ladybirds are known to be attracted to herbivore-induced plant volatiles (HIPVs), little is known about the specific attractive compounds and the effect of F. intonsa-infested lemon plants on the predatory response of C. sexmaculata. Here, we studied the chemical interaction between F. intonsa, C. sexmaculata, and lemon plants. In dual-choice behavioral assays, C. sexmaculata adults significantly preferred volatiles from F. intonsa-infested plants over those from healthy plants. Volatile collection and analysis identified six monoterpenes, five of which (α-pinene, β-pinene, sabinene, myrcene, and eucalyptol) individually attracted C. sexmaculata at specific concentrations. Moreover, a blend of these five compounds, formulated at their optimal attractive concentrations, elicited a stronger attraction in C. sexmaculata than individual compounds, indicating a synergistic interaction. This attractive blend can thus be used to develop a kairomone-based lure to enhance biological control and to complement existing integrated pest management approaches against thrips in lemon agroecosystems.

Systemic insecticides are widely used to control sap-feeding pests, and their risks for natural enemies have become well-assessed in the past decades. However, most of these risk assessments focused on the direct effects when natural enemies come in contact with the sprayed leaves or forge contaminated prey. Consequently, the indirect impacts of systemic insecticides on regulating plant volatile organic compounds (VOCs) and how do these affect natural enemies have been overlooked. In the current study, we examined the indirect impact of imidacloprid soil drenches on prey selection behavior and functional response of the ladybird Propylea japonica. Our findings demonstrated that systemically applied insecticides could negatively affect natural enemy behaviors by disturbing VOCs emitted from plants. Compared with those exposed to fresh air and VOCs emitted from water-treated plants, P. japonica adults exposed to VOCs emitted from imidacloprid-treated plants were less chosen, and their attack rate (a) and handling times (h) markedly decreased, which potentially weaken biological control service. Meanwhile, we also found Frankliniella intonsa was less frequently chosen for imidacloprid-treated plants. Therefore, utilizing systemic imidacloprid to control pests needs to be cautiously considered when integrated pest management strategies are set up.

Streptomyces vinaceus strain SVFJ-07 is a biocontrol bacterium employed to control anthracnose disease caused by Colletotrichum gloeosporioides in Chinese orchids. This study investigated the mechanism of strain SVFJ-07-induced stomatal immunity-related closure in preventing the infection of anthracnose disease. After the foliar application of strain SVFJ-07, we analyzed the differential patterns of stomatal opening in Chinese orchids and measured the hormone levels of abscisic acid (ABA) and salicylic acid (SA). RNA sequencing (RNA-seq) was utilized to examine the differential expression of genes involved in SA and ABA signal transduction and disease resistance genes, which were induced by strain SVFJ-07. The results demonstrated that strain SVFJ-07 inhibited the infection of pathogens by inducing stomatal closure. Compared with the control group, the foliar application of strain SVFJ-07 significantly reduced stomatal length, width, and aperture. Furthermore, orchid plants treated with strain SVFJ-07 and infected with C. gloeosporioides exhibited elevated levels of endogenous ABA and SA, indicating that strain SVFJ-07 enhanced stomatal immunity and disease resistance in these plants. The transcriptome analysis revealed the upregulation of genes associated with stomatal immunity, particularly those involved in plant–pathogen interactions, peroxisome metabolism, plant hormone signaling, and mitogen-activated protein kinase (MAPK) signaling pathways. These findings confirmed that the induction of SVFJ-07 promoted stomatal closure to resist the infection of C. gloeosporioides and induced complex transcriptome-wide changes. Further investigation of the differentially expressed genes enhanced our understanding of the resistance mechanisms induced by S. vinaceus strain SVFJ-07.

Planococcus lilacinus (Cockerell) (Hemiptera: Pseudococcidae) is a global flower and fruit pest, and a severe infestation is currently seen in the sugar apple (Annona squamosa L., Annonaceae) orchards of Zhangzhou, Fujian Province, China. Biological control with entomopathogenic fungi is safe, effective, and long‐lasting, and has potential for the control of mealybugs. In this study, we analyzed the pathogenic characteristics and infection‐related genes of Metarhizium anisopliae (Metschn.) Sorokīn FM‐03, a strain discovered in the sugar apple orchards, against P. lilacinus, to evaluate its biocontrol potential and application prospects against mealybugs. The results showed that M. anisopliae FM‐03 was highly pathogenic against P. lilacinus. At 10 days after infection, the median lethal concentration (LC₅₀) of strain FM‐03 was 1.45 × 10⁵ spores ml⁻¹ and the cumulative corrected mortality was 93%, whereas the median lethal time (LT₅₀) was 5.27 days for treatment with the highest spore concentration (10⁸ spores ml⁻¹). Planococcus lilacinus was primarily infected from the legs, abdominal segments, and body edges, which are sites with less wax. Infection became clearly visible 72 h post inoculation. Substantial changes occurred in activity of fungal enzymes, with peak values of 26 U ml⁻¹ for proteases and 17 U ml⁻¹ for lipases on day 5 post inoculation to enzyme inducing culture media. The activity of chitinases was relatively stable, with a peak value of 8 U ml⁻¹ on day 6 post inoculation. At 3 days post P. lilacinus infection, a total of 1 069 genes were differentially expressed, of which 137 were annotated as infection‐related. Among the 136 upregulated genes, 10 were identified as potentially crucial for infection regulation. These 10 genes could be targeted for subsequent construction of genetically engineered FM‐03 strains, driving the research and development of effective biocontrol agents for P. lilacinus.

Echeveria ‘Perle von Nürnberg’ is a popular ornamental potted plant. In 2017–2018, stem rot lesions caused by Fusarium spp. were repeatedly observed on Echeveria ‘Perle von Nürnberg’ in Zhangzhou, Fujian Province, China. In this study, samples were collected to isolate the pathogen. After morphological observations, molecular identification, and pathogenicity measurements, the pathogen was confirmed as Fusarium oxysporum. Green fluorescent protein was used to label F. oxysporum to observe the pathogenic process in the host plant. Two to three days after inoculation, the pathogen conidia adhered to the surface of the host stem and germinated into hyphae. The hyphae invaded the host cortex through wounds on the plant or the stem-leaf junction. The host stem produced greyish-brown circular or irregular lesions. Five days after inoculation, the expanded hyphae invaded the vascular cylinder and proliferated. The lesions on the host stem became larger and the neighboring leaves gradually fell off. Seven days after inoculation, the thalli continued to proliferate in the host, the hyphae continued to expand, and the host pith was damaged. The lesions on the stem continued to expand; the stems and branches became withered and lodged, and numerous leaves fell off. Given the rapid infection of F. oxysporum in Echeveria ‘Perle von Nürnberg’ plants, necessary prevention and control measures should be employed prior to infection. In summary, this study demonstrated that the pathogen responsible for stem rot disease in Echeveria ‘Perle von Nürnberg’ is F. oxysporum and further revealed the invasion modes and pathways of F. oxysporum in this plant, providing an empirical basis for the diagnosis and treatment of this stem rot pathogen.