Fuxin Li, Jingxian Ye, Jianjun Hao, Zexiao Liu, Dongyin Yi, Gaoming Zhang, Xinyu Luo, Yang Bi
Background: Prochloraz (Pro) is a broad-spectrum fungicide that is effective against various plant pathogens, including Colletotrichum fructicola, the causal agent of strawberry anthracnose. However, its limited absorption restricts its effectiveness. In this study, zeolitic imidazolate framework-8 (ZIF-8) was utilized as a nanocarrier and combined with the fungicide prochloraz (Pro) to develop an effective delivery system (Pro@ZIF-8), improving the fungicidal activity of prochloraz.
Results: Characterization confirmed that Pro@ZIF-8 possesses a distinct dodecahedral crystal structure with an average particle size of 139.6 nm. The system exhibited pH-sensitive release, with 89.8% of the prochloraz released within 24 h at pH 5.0, while remaining stable at pH 7.4. Antifungal assays demonstrated that Pro@ZIF-8 had an EC50 of 0.0150 mg L-1 against C. fructicola, which was significantly lower than that of free prochloraz (0.0429 mg L-1). Pro@ZIF-8 effectively delayed disease lesion development on strawberry leaves and fruits inoculated with C. fructicola. Under storage conditions, Pro@ZIF-8 prevented pathogen infection and kept the fruit fresh for an extended period. Additionally, by tracking fluorescein isothiocyanate (FITC)-labeled ZIF-8 after foliar and root applications, it was confirmed that it was systemically transported within strawberry plants.
Background: Unmanned aerial spraying systems (UASSs) are increasingly used in crop protection. There are, however, considerable concerns regarding pesticide drift during their field application, which poses potential environmental risks. Reducing drift while maintaining efficiency is therefore critical. In this study, an octocopter UASS with centrifugal nozzles was tested under varying spray parameters using a modified ISO 22866 method. The effects of droplet size, flight speed and flight height on target deposition and downwind drift were evaluated under two crosswind conditions, and UASS performance was compared with that of a conventional boom sprayer.
Results: The downwind cumulative drift percentage of the UASS is 62.8-811.7%, which is 1.5-17.9 times that of boom sprayers, depending on the operational parameters of the UASS. Droplet size, flight speed and flight height had significant effects on UASS drift, while flight height was the most critical in determining droplet drift and deposition. Droplet size exerted a stronger influence on airborne drift than flight speed, while neither droplet size nor flight speed had a significant impact on target-area deposition. Lowering the flight height to below 3 m should be considered first to reduce drift risk during operations.
Background: Intraguild predation (IGP) regulates predator populations through direct predation and risk effects, shaping the life-history traits of intraguild prey. This study examines the impacts of IGP on life-history traits of two biocontrol agents, Neoseiulus barkeri and Scolothrips takahashii, reared on their shared prey Tetranychus urticae, using age-stage, two-sex life-table analysis and computer simulations.
Results: Life-table analysis revealed that IGP significantly reduced pre-adult survival of both predators. Neoseiulus barkeri developed faster, but exhibited reduced fecundity under IGP, which resulted in declines in its net reproductive rate (R0, from 30.76 to 10.51 offspring per individual), intrinsic rate of increase (r, from 0.2555 to 0.1872 day-1), and finite rate of increase (λ, from 1.2911 to 1.2059 day-1). Conversely, S. takahashii maintained stable development and fecundity, showing no significant differences in R0, r, λ and mean generation time (T) between IGP and control groups. The net predation rate (C0) of N. barkeri decreased from 381.00 to 172.97 prey per individual, and that of S. takahashii from 416.58 to 25.31, under IGP. Computer simulations indicated that IGP led to smaller populations and reduced predation potential for N. barkeri, whereas S. takahashii showed an increase in both.
Background: The rapid evolution of insecticide resistance in the whitefly Bemisia tabaci underscores an urgent need for integrated pest management strategies that prioritize biological control. Aphelinid parasitoids such as Encarsia formosa and Eretmocerus hayati are key natural enemies of B. tabaci. However, their biocontrol efficacy remains highly temperature-dependent, raising concerns given current climate warming predications. Here, we examined the physiological and molecular responses of B. tabaci and its two aphelinid parasitoids across a thermal gradient (20-35 °C). Their development, survival, antioxidant activity, energy reserves and transcriptomic profiles were assessed, with emphasis on comparisons between optimal (26 °C) and stressful (32 °C) conditions.
Results: Our results revealed a narrow thermal optimum at 26 °C for B. tabaci development and survival. En. formosa exhibited faster development at higher temperatures but suffered a sharp decline in survival above 32 °C. By contrast, Er. hayati maintained high survival and developmental stability up to 32 °C; outperforming the other two species at 35 °C. Longevities decreased for all three species as temperature increased. Under heat stress, species-specific changes in antioxidant defense and metabolism were observed. These findings were supported by transcriptome data, which highlighted differential expression of genes involved in oxidative stress, energy metabolism and heat shock response. These molecular patterns clarify the physiological basis for divergent thermal tolerance observed among the different insects.
Noel L Knight, Kul C Adhikari, Wesley J Mair, Kejal Dodhia, Katherine G Zulak, Francisco J Lopez-Ruiz
Background: Decreased sensitivity to fungicides impacts the effectiveness of fungicide applications for managing plant disease, in some cases resulting in field-level failures. Knowledge of the frequency of decreased sensitivity in field populations is critical for evaluating risks for disease control. This study applied a droplet digital PCR detection approach to assess pathogen populations and quantify the frequencies of alleles associated with decreased sensitivity to either demethylation inhibitor (DMI) or succinate dehydrogenase inhibitor (SDHI) fungicides in Pyrenophora teres causing net blotch on barley in Western Australia.
Results: Pyrenophora teres f. maculata was the most frequent form of the pathogen in the sampled region. Frequencies of decreased fungicide sensitivity alleles varied, being as great as 92% for the PtTi insertion in the Cyp51A promoter, 88% for SdhC-S75, and 28% for Cyp51A L489-2. Impacts of cultivar selection and weed hosts on the presence and survival of pathogen populations with decreased fungicide sensitivity were observed.
Background: Stem rot caused by Fusarium solani significantly threatens passion fruit production. However, the pathogenic mechanisms and host defenses remain unclear. We investigated hormonal dynamics, gene regulatory networks, and pathogenic factors during F. solani infection among resistant and susceptible passion fruit cultivars.
Results: The susceptible cultivar exhibited significantly higher levels of auxin (indole-3-acetic acid, IAA), salicylic acid (SA), jasmonic acid (JA), and abscisic acid (ABA), accompanied by up-regulated expression of auxin biosynthesis (AMI1, AAO1) genes. The pink module in the weighted gene co-expression network analysis correlated strongly with JA, SA, ABA, and tryptophan; hub genes included IAA-amido synthetase and WRKY transcription factors. Enrichment of cell wall-degrading enzymes strongly correlated with SA, JA, ABA and tryptophan levels. Hence, F. solani may manipulate host hormone signaling and secrete pectin lyases to facilitate infection.
Li-Jing Zhang, Bao-Qi Zhang, Jun-Xia An, Zhong-Qi Pan, Hong-Jie Liang, Yu-Chen Sun, Zhi-Jun Zhang, Ying-Qian Liu
Background: Bacterial leaf blight caused by Xanthomonas oryzae pv. oryzae (Xoo) severely threatens global rice yields. With increasing resistance to conventional antibacterial agents, new antibacterial agents are urgently needed. This study aimed to optimize the cyanobacterial metabolite tjipanazole D to develop a derivative with enhanced antibacterial activity against Xoo and evaluate its mechanism of action.
Results: Derivative Y-4-1 was successfully synthesized using a fluorination substitution strategy. This derivative Y-4-1 exhibited significantly enhanced antibacterial efficacy against Xoo (minimum inhibitory concentration = 6.25 μg/mL, compared with 100 μg/mL for tjipanazole D). Mechanistic studies revealed that Y-4-1 exerted its antibacterial effects by disrupting the cell membrane of Xoo, inhibiting xanthomonadin biosynthesis, and aggravating oxidative damage. Furthermore, biofilm formation was inhibited in a dose-dependent way by reducing the production of Xoo extracellular polymers such as exopolysaccharides and extracellular enzymes and inhibiting Xoo motility, and ultimately resulting in bacterial death. RNA sequencing and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis indicated that differentially expressed genes were significantly enriched in key pathways such as plant-pathogen interactions and ribosome biogenesis. Notably, the mechanisms regulating biofilm formation play a crucial role in mediating plant-pathogen interactions.
Jianqing Ma, Ning Wang, Jian Zhang, Keran Li, Li He, Yongpan Xu, Keran Wang, Gangyong Zhao, Dandan Cao
Background: Root-knot nematode (RKN) disease caused by Meloidogyne incognita leads to severe agricultural losses. Our previous study found that Bacillus velezensis RKN1111 induces resistance in cucumber, but its mechanism remained unclear.
Results: Integrated transcriptomic and metabolomic analyses revealed that RKN1111 treatment significantly upregulated the CsHPD gene and its product α-tocotrienol in the ubiquinone and terpenoid-quinone biosynthesis pathways. Overexpression of CsHPD significantly reduced the infection rate of second-stage juveniles and the number of root galls by 24.44% and 56.34%, respectively (P < 0.05). By contrast, CsHPD silenced increased these two parameters by 32.99% and 49.66%, respectively (P < 0.05). In addition, a low concentration of α-tocotrienol (<30 μg/mL) significantly decreased gall formation in pot experiments (P < 0.05), with a maximum reduction of 52.84%.
Wanxin Cai, Xuan Zhang, Jixi Ma, Zhanghui Liu, Christopher H Dietrich, Xiangqun Yuan
Background: Stictocephala bisonia (Hemiptera, Membracidae), a North American invasive pest, has now spread across the northern hemisphere and was first reported in China in 2017. As a polyphagous invasive pest, its continued spread and related damage have become a growing concern in several countries in the northern hemisphere RESULTS: To investigate how it adapts to new invasion areas, we assembled a high-quality, chromosome-level genome of Sti. bisonia. The genome is ~1.8 Gb in size and comprises 11 chromosomes, among which chromosome 9 is identified as the sex chromosome. BUSCO analysis indicated that the genome has a high quality with a completeness of 96.8%. The genome contains 60.5% repetitive sequences, has a GC content of 33.99%, and contains 24 372 predicted protein-coding genes. Comparative genomic analysis revealed significant gene family expansions in Sti. bisonia genome, including the detoxification-related P450 and ABC gene families, the chemosensory-related CSP gene family, and the immune-related PGRP gene family. Among positively selected and rapidly evolving genes, several candidates associated with adaptation were identified. Such as the Creb gene (related to detoxification); Pnlip, Y-box, and Hs3st genes (related to cold resistance); and Relish and MKK genes (related to immunity). Notably, Creb, Pnlip, and Hs3st genes are all positively selected and rapidly evolving genes, indicating their potentially important roles in the Sti. bisonia genome.
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