Plant Disease

Vein clearing of zucchini (VCZ) and bacterial leaf spot (BLS) are caused by various strains of the Pseudomonas syringae species complex that infect zucchini (Cucurbita pepo) seeds. VCZ strains have a narrow host range of cucurbits and affect only seedlings, whereas BLS strains have a broader host range and cause symptoms on adult plants. A multiplex qPCR test showed that VCZ strains predominated in infected seed lots produced in different countries. We surveyed hybrid seed crops grown in parallel in two French regions to address inoculum sources. According to DNA-based approach, parental seed lots were positive to BLS strains, although no culturable bacteria were recovered. Hybrid seed lots produced in the Rhone Valley (southeastern France) showed higher infection rates than those produced in Limagne (central France), and VCZ strains were recovered only from the Rhone Valley. Two representative strains of VCZ and BLS colonized seeds through the vascular and floral pathways, whereas only the BLS strain was transmitted through the pericarp. These findings suggest that floral transmission, potentially mediated by pollinators, could explain the predominance of VCZ strains under favorable regional conditions, and that pericarp transmission in BLS strains could be linked to their capacity to cause disease on adult plants. Furthermore, some infections undetected in seeds became apparent after germination, indicating that testing germinated seeds rather than seeds could help seed industry to take in account only bacterial infections transmitted to the seedling. Together, these results provide valuable insights into the epidemiology of P. syringae transmission to zucchini seeds.

L-phenylalanine (Phe) is converted via the phenylpropanoid pathway into phenolic compounds, and elevated phenolic/flavonoid levels are generally associated with enhanced plant resistance. We previously showed that exogenous Phe suppresses the necrotrophic fungus Botrytis cinerea in petunia, chrysanthemum, determinant tomato, and several postharvest diseases. Here, we expanded evaluation to a broad range of pathosystems, including an indeterminate greenhouse tomato cultivar, multiple dicot species, and the monocot wheat. Phe, applied as spray or drench across concentrations, was consistently effective at [≥]4 mM. It reduced disease severity in diverse systems: Sclerotinia sclerotiorum (tomato, sweet basil, cucumber, lettuce), Leveillula taurica and Oidium neolycopersici (tomato), Podosphaera xanthii (cucumber), wheat foliar pathogens (Blumeria graminis f. sp. tritici, Zymoseptoria tritici, Puccinia triticina, P. striiformis f. sp. tritici), the oomycetes Pseudoperonospora cubensis (cucumber leaves) and Pythium aphanidermatum (roots), bacterial pathogens (Pseudomonas syringae pv. tomato and Clavibacter michiganensis subsp. michiganensis) and Tomato brown rugose fruit (ToBRFV) that belongs to the Tobamovirus genus. Phe was effective on both young and mature leaves and often performed comparably to chemical fungicides; combinations rarely improved control, except for enhanced activity with pyrimethanil against B. cinerea in tomato. Synergistic effects were observed when Phe was combined with an adjuvant against tomato powdery mildews. A formulated product (NaturaFend 550 SP) was more effective than non-formulated Phe in B. cinerea (tomato) and P. xanthii (cucumber). Application timing also influenced efficacy, with treatment 5 days before infection providing superior control compared with 0, 3, or 7 days. Overall, Phe effectively controlled biotrophic and necrotrophic fungi, oomycetes, bacterial pathogens and a virus across diverse crops under experimental greenhouses and commercial like conditions.

Tomato worldwide production is increasingly challenged by complex disease outbreaks involving multiple interacting pathogens. In Israel, recent years have seen a marked rise in vascular collapse symptoms in greenhouse-grown tomatoes, coinciding with the widespread emergence of tomato brown rugose fruit virus (ToBRFV) and pepino mosaic virus (PepMV). Here, we investigated the bacterial and viral agents associated with these outbreaks and examined how viral infection influences the development and severity of bacterial diseases that cause vascular collapse. Surveys conducted between 2021 and 2026 revealed that tomato pith necrosis outbreaks were associated with a diverse bacterial community dominated by members of the Pseudomonadales and Enterobacterales, while bacterial canker outbreaks were exclusively linked to Clavibacter michiganensis. Multilocus sequence analysis showed that pith necrosis-associated Pseudomonas isolates clustered primarily within the P. syringae, and P. corrugata phylogroups. Pathogenicity assays demonstrated that only a subset of pith necrosis-associated bacteria, P. mediterranea, P. capsici, P. viridiflava, and Xanthomonas euvesicatoria pv. perforans, induced pith necrosis under controlled conditions, with high variability in symptom severity. Co-inoculation experiments showed that ToBRFV- and PepMV-infected plants exhibited a 40-100% increase in lesion size following inoculation with pith necrosis-associated bacteria, without a corresponding increase in bacterial colonization, whereas the same viral infections attenuated wilt symptoms caused by C. michiganensis. Together, our findings demonstrate that endemic viral infections differentially modulate bacterial disease outcomes, either exacerbating or attenuating symptoms depending on the pathogen. These results highlight the importance of multi-pathogen interactions in disease severity and have important implications for tomato disease management.

Rice blast disease, caused by Magnaporthe oryzae (formerly as Pyricularia grisea), is a major threat to rice production globally, causing devastating yield losses up to 30-50% of rice production annually. Here, we analysed 48 isolates collected from rice fields in the Terai foothills of the Himalayas, India, to assess pathogen occurrence in a new agroecological zone, potentially influenced by climate change and favourable environmental conditions. All isolates were screened for virulence and pathogenicity, and two highly virulent isolates (UBKV1 and UBKV2) were selected for detailed characterization of their morphological, growth, and genetic variability. Significant differences (p-value=4.16 x 10-) were observed in conidial dimensions, with UBKV2 producing larger spores (33.61 {micro}m) compared to UBKV1 (28.07 {micro}m). In terms of growth, mycelial biomass (fresh weight) and sporulation intensity was also higher in UBKV2 (22.98 g and 2315.5) than UBKV1 (15.82 g, and 1812.3) when they grew under the same conditions. Distinct colony growth patterns were observed on different media, particularly on Mathurs medium and Rice Straw Extract Dextrose Oatmeal Agar, where UBKV2 exhibited suppressed growth and unique pigmentation. Phylogenetic analysis of the ITS region revealed sequence similarities ranging from 95.11% to 100% among the isolates. UBKV2 showed closer genetic relatedness to isolates from Odisha (96.95-97.23%) than to UBKV1 (95.57%), highlighting significant genetic differentiation. These findings demonstrate substantial morphological, cultural, and genetic variation within M. oryzae populations in the Terai foothills, providing important insights into pathogen evolution, virulence mechanisms, and implications for region-specific resistance breeding strategies.

Pseudocercospora fijiensis is the causal agent of Black Leaf Streak Disease (BLSD), also known as black Sigatoka, in banana. The disease affects many banana varieties, including the highly susceptible Cavendish banana that dominates global production and the export trade, and several cooking bananas that are a staple food for hundreds of millions of people worldwide. Currently, the disease is controlled using preventative fungicide treatments with up to 70 applications per year in Cavendish plantations, which accounts for approximately 30% of the production costs. Resistant cultivars are required for more sustainable production, but no resistance gene to BLSD has been identified. This is partly due to the poor genetic amenability of P. fijiensis and the lack of methods for functional gene analysis. To address these limitations, we developed a CRISPR/Cas9-mediated transformation system specifically optimized for P. fijiensis. We established a protocol to produce protoplasts, evaluated their capacity to regenerate into new colonies, and assessed antibiotic sensitivity. Subsequently, we confirmed the integration of foreign DNA, including resistance markers, using PEG-mediated transformation. We demonstrated targeted transformation using CRISPR-Cas9 to knockout the polyketide synthase gene PKS10-1, which is responsible for the production of the pigment melanin, and the mitogen-activated protein kinase (MAPK) gene Fus3. Following the successful generation of knockout mutants for these genes, achieving gene targeting efficiencies of respectively 96% and 58%, we subsequently generated knockout mutants of the renowned effector Avr4 in P. fijiensis. The resulting mutants exhibited no reduction in virulence on the susceptible banana cultivar Cavendish. In addition, we used the wild-type isolate and Avr4 knockout strains to test the resistant banana accession Calcutta 4. Contrary to a previous study, we demonstrate that Avr4 does not explain the resistance of Calcutta 4, suggesting that resistance is instead triggered by the recognition of other hitherto unknown effectors. The established CRISPR/Cas9-mediated disruption system is highly efficient and enables routine functional gene characterization, which will help to elucidate genes involved in banana-P. fijiensis interaction, thereby supporting the discovery of resistance genes against BLSD.

Septoria nodorum blotch (SNB) and tan spot (TS) wheat diseases are caused by necrotrophic fungal pathogens Parastagonospora nodorum (Pn) and Pyrenophora tritici-repentis (Ptr), respectively. Although recognised as premier model pathosystems for our understanding of necrotrophic effectors, no resistance mechanism has been reported in both diseases. Here, two SNB and TS resistance wheat lines ( 56:ZWB11 and 105:ZIF14) derived from the Australian national germplasm evaluation programme (CAIGE) were used to develop a double haploid mapping population. Two Pn and Ptr isolates of different pathotypes, their respective culture filtrates and effector SnTox267 were evaluated on the population. Genetic analysis of Ptr conidial inoculation of race 1 and race 2 identified a major resistance quantitative trait locus (QTL) (QTs.cur-1B) on chromosome 1B, while resistance to SNB was explained by several minor QTL. SnTox267 sensitivity was mapped to six locations (2A2, 2A3, 2B1, 2D3, 5B and 7B1) with only one QTL co-localized to known corresponding gene Snn7. Sensitivity loci 5B and 7B1 also conferred SNB resistance at seedling and adult stages. Two QTL on chromosome 2D1 and 7B2 were common in both SNB and TS, associated with disease at seedling stage and culture filtrate bioactivity, respectively. Resistance responses of 56:ZWB11 and 105:ZIF14 were confirmed cytologically, however, distinct responses were observed on wounded leaves. The defence responses were more effective against Ptr, while resistance to Pn infection was likely a combination of lack of susceptibility and effective physical barriers. Overall results demonstrated the distinction between the underlying resistance mechanisms to TS and SNB.

Cultivar susceptibility strongly influences the epidemiology of vector-borne plant diseases, and understanding cultivar-specific variation can inform management strategies. This is particularly relevant for flavescence doree, an incurable grapevine disease associated with a phytoplasma and transmitted by the leafhopper Scaphoideus titanus. In this study, we investigated the susceptibility of the main Swiss varieties, by combining controlled insect-mediated inoculation experiments with complementary field analyses conducted at progressively finer spatial scales. Together, these approaches allowed us to compare both infection probability and phytoplasma relative titre under standardised transmission conditions with disease incidence and relative titre under natural epidemiological conditions. For most cultivars, laboratory results were broadly consistent with field observations. However, a marked discrepancy emerged in the relative infection pattern between the two main grapevine cultivars grown in Switzerland: Chasselas and Pinot Noir. Under controlled conditions, they did not differ significantly in either their probability of infection or the phytoplasma relative titre, indicating no detectable difference in susceptibility to phytoplasma infection. In contrast, Pinot Noir consistently showed higher disease incidence than Chasselas under natural conditions. This pattern was observed across all spatial scales examined, from regional surveys to neighbouring vineyard plots, and was mirrored by higher phytoplasma relative titres. Importantly, under controlled conditions, S. titanus mortality during the one-week inoculation period was significantly higher on Chasselas than on Pinot Noir, indicating that Chasselas may provide a less favourable host for S. titanus. Together, these findings support the hypothesis that differences in field disease incidence between these cultivars may arise from differences in vector performance rather than intrinsic susceptibility to phytoplasma infection. This highlights the importance of considering plant-vector interactions, alongside susceptibility to infection, when assessing cultivar-specific vulnerability to vector-borne plant diseases.

Maize yellow mosaic virus (MaYMV) is an emerging polerovirus of corn and other grass species. Due to its broad host range and transmission by multiple aphid species, management strategies such as crop rotations, pesticides, and weed control are likely ineffective. Therefore, resistant cultivars are needed. In this study, we characterized the Goodman 282 maize diversity panel for its response to MaYMV. Leaf reddening symptoms were quantified, and diagnostics were performed to assess infection and obtain a semi-quantitative measure of virus titer. Low titer lines and inbreds representing symptomatic and asymptomatic infected phenotypic classes were characterized further by RT-qPCR. Genome-wide association studies were performed using MLM, FarmCPU, and BLINK models to identify SNPs associated with disease. In total, 64% of lines were asymptomatically infected. Although all lines tested positive for infection by MaYMV in at least one experiment, Ky226 had reduced viral titer compared to other lines. Sixteen quantitative trait nucleotides (QTN) were identified, many of which are linked to genes implicated in flavonoid, carotenoid, and phenolic metabolic pathways as well as antiviral defense. Notably, a QTN associated with a chalcone synthase, a key enzyme in the flavonoid biosynthesis pathway, was detected by even the most conservative, MLM model. These results indicate that the genetic architecture of corn in response to MaYMV is complex, and that developing immune cultivars may not be achievable using natural sources of genetic variation. However, this study provides a foundation for breeding maize with improved tolerance and advances our understanding of host response to MaYMV infection.

BACKGROUNDBlackleg, caused by Leptosphaeria maculans, is a major disease limiting oilseed rape production worldwide, and its management increasingly requires sustainable alternatives to chemical fungicides. In this study, we evaluated the antagonistic activity and plant growth-promoting potential of three endophytic bacteria, Bacillus velezensis Bro5, Bacillus subtilis Bro11, and Pantoea agglomerans Bru13, against a geographically diverse collection of 139 L. maculans isolates from five oilseed rape-producing regions of Argentina. RESULTSDual culture assays revealed strong inhibitory activity by Bro5 and Bro11, with mean inhibition rates of [~]80% across isolates, while Bru13 showed variable inhibition (<75% for most isolates). Greenhouse and growth chamber assays confirmed the protective potential of these strains. At the cotyledon stage, Bro11 and Bro5 reduced lesion size by 47% and 28%, respectively, while their combination achieved a 51% reduction. In greenhouse trials, combined application of Bro5 and Bro11 reduced stem base necrosis by 45% and increased the proportion of plants with [&le;]50% damage to 98%, compared to only 70% in controls. Key disease metrics, including disease index, incidence, and severity, decreased by 60%, 23%, and 26%, respectively. Beyond pathogen suppression, inoculation with the Bro5-Bro11 consortium enhanced plant growth, increasing shoot biomass by 89% at early stages, and improving stem dry weight and diameter by 10% and 35%, respectively, at maturity. CONCLUSIONThese findings highlight the robustness of Bacillus endophytes as biocontrol agents, their capacity to suppress diverse pathogen isolates, and their dual role in plant growth promotion, supporting their potential integration into sustainable blackleg management programs.

Tomato (Solanum lycopersicum L.) is one of the most important vegetable crops in Nigeria, serving as a major source of income, nutrition, and raw material for food industries. However, its production is severely constrained by Fusarium wilt, a destructive soil-borne disease caused by Fusarium oxysporum f. sp. lycopersici. This study investigated the prevalence and severity of Fusarium wilt on tomato in Chikun Local Government Area (LGA) of Kaduna State, Nigeria. Field survey and laboratory analyses were conducted on forty-five tomato samples from three tomato farms Kujama, Kakau, and Rido. The samples were examined for disease incidence and severity. Data were analyzed using descriptive statistics and Chi-square tests. The overall disease incidence was with Rido recording the highest infection rate (80.0%), followed by Kujama (60.0%) and Kakau (40.0%). Among plant parts, the stem exhibited the highest infection frequency (80.0%), while leaves and fruits had 60.0% and 40.0% incidence respectively. Chi-square analysis indicated no significant difference (p > 0.05) in disease incidence among farms and plant parts, suggesting uniform pathogen distribution. The research recommends the adoption of integrated disease management strategies and improved farmer awareness to mitigate the impact of the disease and ensure sustainable tomato production.

Red crown rot of soybean (RCR), caused by Calonectria ilicicola, is an emerging soilborne disease whose quantification is challenging due to its complex symptom development across root and foliage levels. This study developed and evaluated a multi-scale framework to improve the assessment of RCR severity from controlled environments to field conditions using root imaging and standardized visual scales. Under controlled conditions, a standard area diagram (SAD) for root necrosis was developed and validated, and SAD-assisted evaluations significantly improved accuracy, precision, and inter-rater agreement compared with unaided assessments. In field conditions, a diagrammatic symptom scale (DSS) was developed using consensus-rated images from experts and showed high reliability, repeatability, and reproducibility across 18 raters, with strong intra- and inter-rater agreement. This study developed and evaluated complementary methods to improve the assessment of RCR severity from controlled environments to field conditions using root imaging and standardized visual scales.

Fungal plant pathogens can be affected by the bacteria they interact with in their environment, yet the characterization of these interactions beyond direct antagonism is lacking, especially in the case of endohyphal bacteria (EHB). Though limited in characterized examples, EHB can alter disease severity of their fungal host, providing either a potential tool or target for control. We screened isolates of Fusarium oxysporum f. sp. niveum (FON), an important soil-borne watermelon pathogen, using 16S PCR and fluorescence in situ hybridization microscopy to identify novel EHB. A symbiont of FON AS124 was identified to be a Paenibacillus sp. through genome sequencing and average nucleotide identity. To begin characterizing this relationship, we conducted watermelon infection assays using FON cured of its symbiont, the native association, and a coinoculation of fungi and bacteria. Disease severity was reduced in watermelon seedlings inoculated with the native association, though not in the coinoculation, and Paenibacillus sp. CB74 did not alone promote plant growth or inhibit fungal growth. This study shows an important functional outcome, reduced disease, for a novel symbiosis between FON and Paenibacillus sp. CB74, setting up further investigation into the mechanisms behind this outcome and the application of this interaction. ImportanceFungi pose a challenge in both the field and hospital as antifungal resistance rises and chemical control is increasingly scrutinized. In plant pathogenic fungi, endohyphal bacteria may present alternative targets or mechanisms of fungal control. These relationships are observed across diverse groups of fungi and bacteria, though few have been studied to the point of understanding impact. To contribute to the small but growing catalog of known endofungal bacterial relationships, we identified a novel symbiosis and began characterizing its functional outcomes with plant infection assays. The identified bacterial symbiont does alter disease severity of the fungal host offering a new system for both application and study of fungal pathogenesis.

Peanut smut, caused by Thecaphora frezzii, is an important constraint to peanut production in Argentina, but quantitative estimates of yield losses across environments remain limited. We quantified the relationship between disease incidence and kernel yield using 922 observations from 26 field studies conducted in Cordoba, Argentina, between 2021 and 2025. Study-specific incidence-yield relationships were analyzed using linear regression, random-effects meta-analysis, and linear mixed-effects models. Peanut smut incidence was consistently associated with yield reduction across studies. The estimated damage coefficient ranged from 24.2 to 28.7 kg ha-{superscript 1} per 1% increase in disease incidence, corresponding to a relative yield reduction of 0.74-0.87% of attainable yield. In contrast, attainable yield varied markedly among studies, ranging from 1,370 to 5,409 kg ha-{superscript 1}. Although an exploratory segmented analysis suggested a breakpoint near 12% incidence, subsequent moderator analyses, study- specific regressions, and normalized response curves provided no evidence of a biologically meaningful change in the damage coefficient across incidence or yield classes. These results indicate that differences among environments were primarily associated with attainable yield rather than with changes in the magnitude of disease-associated yield loss. The resulting damage function provides a quantitative basis for yield-loss assessment and disease management in peanut.

Septoria nodorum blotch (SNB) is an economically important fungal disease of wheat caused by Parastagonospora nodorum. It is primarily controlled by the breeding of resistant wheat cultivars, but experience over the last 50 years shows that new pathogen populations soon evolve that are more virulent on the current popular cultivars. In this study, we assembled a panel of 360 P. nodorum isolates. The collection resolved into eight subpopulations. One core and seven transient populations were found possessing contrasting characters in term of spatial and temporal distribution, mating-type, effector haplotypes and patterns of intact and degraded copies of a Tc-1 mariner transposon, called Molly. Molly can proliferate and randomly insert throughout the fungal genome. Its multiplication in sexual population likely triggered RIP which partially explains the extensive genetic diversity and explains the ability to form new adapted lineages and the observed population structure of this important pathogen of wheat. When tested on wheat, the recently emerged groups exhibited greater pathogenicity on modern elite cultivars consistent with the low-amplitude boom-and-bust cycle observed previously. It is possible that active copies of Molly transpose and contribute to both the birth and death of the transient groups. This study identified and characterised a fungal specific transposable element (TE) which plays a vital role in shaping Australian P. nodorum population structure and creating extensive genetic diversity which potentially leads to better adaptation of the pathogen. The study suggests practical measures to improve the efficiency and longevity of resistance breeding for SNB.

Bugtok disease remains a major bacterial constraint of cooking banana production in the Philippines and is characterized by vascular discoloration, fruit browning, and progressive decline associated with members of the Ralstonia solanacearum species complex that infect banana inflorescences and fruits. This study investigated whether insects visiting Saba banana flowers in Indang, Cavite harbor R. solanacearum, with emphasis on the possible role of Thrips hawaiiensis as a possible candidate vector under field conditions. Destructive sampling was conducted three times in a Saba-monoculturing farm with high reported bugtok incidence, targeting flowers present at the time of collection and prioritizing insects recovered directly from banana inflorescences. Field-collected insects were surface sterilized, subjected to bacterial isolation, and confirmed by PCR using RSSC-specific and phylotype-specific primers; representative thrips were then morphologically identified. Preliminary acquisition assay with infected flowers for 1 and 3 days was conducted using field collected T. hawaiiensis from a non-Bugtok infested farm in Laguna. Among the insects recovered, thrips and stingless bees (Tetragonula spp.) were the most prominent flower visitors, but only thrips yielded internal detection of R. solanacearum after surface sterilization and homogenization, supporting the presence of the pathogen within the insect body rather than simple external contamination. Morphological characters of the positive specimens were consistent with T. hawaiiensis, including a pale antennal segment III, bicolored body, paired pronotal posteroangular setae, discal setae on abdominal sternite VII, and a complete comb on abdominal tergite VIII. In preliminary acquisition tests, healthy T. hawaiiensis exposed to infected flowers acquired the pathogen at mean positivity values of 1.75 {+/-} 1.50 after 1 day and 2.67 {+/-} 4.72 after 3 days, whereas control thrips remained negative. These findings provide field-based evidence that T. hawaiiensis can acquire R. solanacearum from infected Saba flowers and should be considered in Bugtok epidemiology and integrated disease management in Luzon.

Leptosphaeria maculans is a plant-pathogenic fungus that infects Brassica species, including Brassica napus (oilseed rape). Breeding oilseed rape varieties with genetic resistance is an efficient way to control the disease; however, L. maculans can adapt and overcome these resistances. Understanding the mechanisms that enable L. maculans to adapt is crucial for managing the emergence of better-adapted isolates. Brassica carinata, the Ethiopian Mustard, although closely related to B. napus, is considered a nonhost species of L. maculans because this fungus cannot infect it. Despite the extreme resistance of B. carinata, one natural L. maculans isolate has been identified as unable to infect B. napus, causing moderate and atypical symptoms on this species. We performed a cross between this isolate and an isolate adapted to B. napus, followed by a QTL analysis, which identified seven QTL, each encompassing candidate genes involved in L. maculans adaptation to B. carinata or B. napus. Additionally, we observed transgression in the progeny, wherein a few strains caused significantly more or less aggressive symptoms on both species of Brassica. We found that epistasis within the L. maculans genome contributes to the observed transgression. These initial findings provide further opportunities to study the adaptive capacities of L. maculans, as well as data to initiate analysis of the extreme resistance of B. carinata to L. maculans. HighlightsO_LISeven pathogenicity QTL identified, carrying several interesting candidate genes C_LIO_LITransgression of some progeny isolates on B. napus and B. carinata was reported C_LIO_LIEpistasis plays a significant role in the adaptation of L. maculans toward host and nonhost Brassica species C_LI

Endophytic biocontrol agents may contribute to grapevine health, but their ability to establish, persist, and move within woody tissues remains poorly understood. In this study, a stem injection method was developed to introduce Pseudomonas chlororaphis M71 and Trichoderma atroviride SC1 into rooted and grafted grapevine plants, and their spatial and temporal colonization patterns were compared with the movement of a dye tracer. The dye tracer moved rapidly through xylem tissues, whereas both microorganisms showed more restricted early distribution. Over time, M71 and SC1 displayed distinct colonization patterns. M71 persisted after injection, but remained localized near the inoculation site, with limited movement toward roots or distal aerial tissues. In grafted plants, M71 recovery depended on the injection site and declined more markedly after rootstock injection than after scion injection. In contrast, SC1 showed broader and more persistent colonization. In rooted cuttings, SC1 was recovered from stem and root tissues up to 56 days post-injection, and in grafted plants it was recovered across the graft union, particularly after scion injection. Microscopy supported internal localization of both microorganisms. GFP-labelled M71 and SC1 hyphae were observed mainly within xylem vessels, and viable microorganisms were recovered from corresponding wood tissues. No contamination was observed in control plants. These results show that beneficial microorganisms can be introduced into grapevine tissues by stem injection and that bacterial and fungal biocontrol agents differ markedly in their internal movement and persistence. IMPORTANCEIntroducing beneficial microorganisms directly into plant tissues could help in establishing protective endophytic populations, but little is known about how such microorganisms move and persist inside grapevine. This study shows that stem injection can deliver Pseudomonas chlororaphis M71 and Trichoderma atroviride SC1 into grapevine tissues without visible phytotoxicity. The two microorganisms followed different colonization patterns. M71 remained mostly localized near the injection site, whereas SC1 spread more broadly and persisted in both rooted and grafted plants. These findings provide a basis for developing targeted endophytic biocontrol strategies in grapevine propagation and early plant establishment. This approach may be particularly relevant for grapevine trunk diseases and other vascular disorders, in which pathogens colonize internal woody tissues.

Light leaf spot (LLS), caused by subcuticular hemibiotrophic ascomycete fungus Pyrenopeziza brassicae, is a major constraint on oilseed rape (Brassica napus) production, yet the genetic and biochemical mechanisms of quantitative disease resistance (QDR) remain poorly defined. Here, disease phenotyping, pathogen quantification, microscopy, gene expression profiling and glucosinolate (GSL) analysis were integrated to dissect resistance mechanisms in B. napus. Disease assays of 19 diverse lines revealed clear contrasts between susceptible and resistant genotypes, with the commercial cultivar Ambassador showing a phenotype inconsistent with the UK Recommended List rating. Microscopy demonstrated that resistance within doubled haploid line Cubs Root does not inhibit spore germination or penetration but restricts hyphal branching and subcuticular colonisation from 4 to 8 days post-inoculation. Expression profiling of seven candidate gene expression markers (GEMs) and pathogenesis-related PR1 showed that cinnamate-4-hydroxylase, phospholipase C4, {beta}-adaptin, universal stress protein and the 40S ribosomal subunit protein S24 were strongly pathogen-induced in resistant lines, whereas a BAHD acyltransferase, a putative susceptibility factor, was induced only in susceptible cultivars. GSL profiling identified negative correlations between disease severity and total GSLs, particularly aliphatic and aromatic GSLs, with 2{square}phenylethyl and 7-methylsulfinyl heptyl GSLs showing the strongest associations with resistance. Together, these results highlight coordinated transcriptional and metabolic responses that limit pathogen proliferation and provide targets for breeding durable LLS resistance in B. napus.

Bacterial leaf blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo), causes yield losses exceeding 50% in affected areas, including the Bagre rice plain in Burkina Faso. Genome-edited (GEd) rice lines have been successful in tackling BB. Modifications in the Xoo virulence protein target site upstream of three SWEET susceptibility genes in two elite rice varieties, IR64 and Ciherang-Sub1, have been demonstrated to confer broad-spectrum resistance to Asian and East African Xoo strains. Here, we evaluate the potential of the GEd lines as a solution for BB management in Burkina Faso. We challenged the GEd lines against five locally collected Burkinabe Xoo strains under controlled green-house conditions and assessed their agro-morphological performance under field conditions representative of local agroecological conditions. Greenhouse pathogen assays demonstrated that GEd IR64 and Ciherang-Sub1 lines were resistant to all tested local Xoo strains across three successive generations. We identified TalC as the primary disease-causing effector in the local Xoo populations. Irrigated field trials conducted over two seasons in the Kou Valley, Burkina Faso, revealed absence of agro-morphological penalties in GEd lines compared to their parental wild-type lines. Observed trait variation was attributable to environmental fluctuations rather than genomic modifications. Collectively, our findings demonstrate that genome editing of the rice lines does not impose growth penalties, and support the suitability of GEd IR64 and Ciherang-Sub1 for large-scale adoption in Burkina Faso, pending multi-location validation and introgression into locally adapted varieties.

Plant health research within National Agricultural Research and Extension Systems (NARES) represents a critical yet neglected pillar of agricultural resilience in sub-Saharan Africa (SSA), where crop productivity remains substantially below global averages due to persistent biotic and abiotic stresses. Although plant health units have a strategic mandate to support crop protection, disease surveillance, and varietal improvement, the institutional capacity of these units across NARES in SSA is not defined. Here, we assessed 36 plant health units across 26 SSA countries to determine research capacity, identify operational constraints, and examine their contributions to crop improvement and food security. Our findings reveal the existence of a strong human capital operating under structurally constrained systems. More than 65% of personnel possess postgraduate qualifications, indicating the presence of a highly trained scientific workforce with considerable potential to drive plant health innovation. However, this expertise is undermined by severe infrastructural and institutional limitations that restrict research delivery. Access to essential facilities remains low, whereby only 53% of respondents had access to plant pathology laboratories, 43% had molecular biology platforms, and 37% had glass/screenhouses, while only 30% of respondents maintained phenotyping infrastructure such as sick plots or endemic/hot spot disease sites. These deficiencies undermine plant health research in areas like biotic stress resistance screening, pathogen diagnostics, and diversity. It was noted that plant health units primarily target staple food crops central to regional food systems, including cereals (maize, rice, sorghum, and millets), legumes (groundnut and cowpea), and root and tuber crops (cassava and potato). All these crops are affected by diverse biotic stresses that include fungi, bacteria, viruses, insect pests, and parasitic weeds. Yet research effectiveness to address these challenges is further constrained by unclear or fragmented protocols, poorly equipped laboratories, weak data capture, and management systems. Critical gaps were consistently identified in pathogen isolation and characterization, disease phenotyping, surveillance and mapping, experimental design, and data management. Workforce composition raises additional concerns regarding long-term system sustainability. Women account for only 18% of plant health personnel, while researchers younger than 35 years represent just 10% of the workforce, reflecting weak generational succession and gender inequity. These demographic imbalances constitute an existential threat to institutional continuity and innovation capacity. In summary, closing these gaps will require coordinated investment in infrastructure, technical training, institutional strengthening, and digital modernization. Equally important is the development of inclusive workforce strategies that improve gender representation and strengthen succession pathways. Unlocking the potential of NARES plant health networks is essential for accelerating resilient crop development, strengthening agricultural productivity, and advancing food security across SSA.