Fusarium wilt, caused by Fusarium udum Butler, is a major biotic constraint limiting pigeonpea (Cajanus cajan L. Huth) productivity in tropical and subtropical regions. Wilt incidence varied widely among 143 pigeonpea genotypes, ranging from 0.40 to 15.60 % at 30 days after sowing and escalating to 2.00 to 78.00 % at 75 DAS. Area under disease progress curve (AUDPC) values ranged from 57.9 to 2258.1, indicating diverse disease progression. Based on the percent disease index (PDI), relative AUDPC (rAUDPC) and r-values, genotypes were categorised as resistant (38.5 %), moderately resistant (37.8 %), susceptible (11.9 %) and highly susceptible (11.9 %). Notable resistant genotypes included Pusa Arhar 21-60, ICP 8863 and NAM 88. In vitro evaluation of seven plant extracts at 10, 15 and 20 ppm using the poisoned food technique revealed significant variation in antifungal activity. Thuja occidentalis L., Cannabis sativa L. and Mentha spicata L. consistently exhibited the highest inhibition in a dose-dependent manner, whereas Chenopodium album L. was least effective. Integration of resistant genotypes with potent botanical extracts offers an eco-friendly strategy for sustainable management of Fusarium wilt in pigeonpea.
Fusarium wilt, caused by Fusarium oxysporum f. sp. ciceris, is a major constraint to chickpea production worldwide, resulting in substantial yield reduction and deterioration of crop quality. The effectiveness of host resistance is often challenged by the emergence of new pathogen races, necessitating the continuous identification of resistant germplasm for breeding programs. This study was conducted to identify chickpea genotypes with resistance to Fusarium wilt and to select promising materials for further breeding. A total of 47 chickpea genotypes, along with two standard checks (Geletu and Dimtu), were evaluated under field conditions during the 2022 and 2023 main cropping seasons using an augmented experimental design. Disease incidence was recorded at both seedling and flowering stages, and genotypes were classified according to the ICRISAT disease rating scale. Considerable variation in disease response was observed among the tested genotypes. Two genotypes exhibited resistant reactions, while seventeen were categorized as moderately resistant. Overall, nineteen genotypes demonstrated desirable levels of resistance and were identified as valuable sources of resistance for future chickpea improvement programs. These genotypes can be advanced to subsequent breeding stages for the development of Fusarium wilt-resistant chickpea varieties.
Daba Etafa· American Journal of Plant Bi...· 0 citations
Bacterial wilt caused by Ralstonia solanacearum is a destructive disease severely restricting tomato (Solanum lycopersicum L.) productivity in tropical and subtropical regions. The purpose of this study was to identify novel sources of resistance and explicate the inheritance pattern of bacterial wilt resistance in tomato. A total of 59 genotypes, including open-pollinated lines, hybrids and breeding accessions, were subjected to screening experiments during two consecutive seasons (2022–2023 and 2023–2024) under controlled net house conditions at Centurion University of Technology and Management and natural epiphytotic field conditions at Indian Institute of Horticultural Research - Central Horticultural Experiment Station , Bhubaneswar, India. Disease severity was evaluated using percent disease index (PDI) and area under disease progress curve (AUDPC). The open-pollinated cultivar ‘Utkal Kumari (BT-10)’ exhibited consistent high resistance, with significantly lower AUDPC values (<150 vs >1800 in susceptible checks) and high survival rates (90 %) across environments. Among others, tomato cultivars Arka Samrat, Arka Abhed and JK Desi, demonstrated significant resistance while genotypes such as Pusa Ruby and EW815 were consistently highly susceptible. A segregating F₂ population derived from a cross between resistant ‘BT-10’ and susceptible ‘Pusa Ruby’ exhibited continuous variation in disease response. Chi-square analysis revealed significant deviation from a 3:1 Mendelian segregation ratio (χ² = 72.30, P < 0.01), indicating a quantitative mode of inheritance. These findings highlight the potential of Utkal Kumari and allied resistant lines as donors for resistance breeding and emphasize the need to integrate robust phenotypic screening with molecular approaches for durable and strategic bacterial wilt management in tomato.
D. Debasmita, D. Sunanya, N. P. Bhagbat et al.· Plant Science Today· 0 citations
Cowpea (Vigna unguiculata subsp. sesquipedalis, also known as yardlong bean) is an important winter horticultural crop in Hainan, and Fusarium wilt seriously threatens its yield and quality. To clarify the pathogen and screen antagonistic bacteria, surveys were conducted in 14 fields across Hainan’s major cowpea-growing areas. The causal agent was isolated, tested for pathogenicity, and identified using morphological and multigene molecular methods. Meanwhile, rhizosphere and endophytic bacteria from healthy plants were screened by dual culture, and candidate strains were phylogenetically analyzed using whole-genome sequencing (285 orthologous single-copy genes). Fusarium wilt occurred in all 14 fields (mean incidence 15.35%, range 3.20–76.40%). Of 44 fungal isolates, six were highly pathogenic and identified as Fusarium oxysporum. Twenty-two bacterial strains showed stable antagonism against F. oxysporum, with inhibition rates ranging from 42.62% to 68.47%. Phylogenetic analysis based on whole-genome sequences identified 15 Bacillus strains to the species level (12 B. velezensis, 2 B. subtilis, 1 B. tropicus), while the remaining seven strains belonged to Lysinibacillus (1), Pantoea (1), Klebsiella (1), Serratia (2), and Pseudomonas (2). Draft genome sequences of all 22 strains were obtained. This study provides a collection of biocontrol bacterial resources and genomic information for managing cowpea Fusarium wilt.
Bao Wang, Da Guan, Wanrong Yan et al.· Horticulturae· 0 citations
Phytophthora blight (PB), caused by Phytophthora cajani, is a key constraint limiting pigeonpea productivity across the tropics and subtropics. Frequent PB outbreaks under erratic rainfall and warm temperatures intensifies the need for a holistic understanding of pathogen variability and stable host resistance. This study evaluated the morpho-cultural, physiological, and molecular diversity of P. cajani and investigated pigeonpea genotypes for resistance against representative isolates. Twenty-two isolates collected from diverse agro-ecological zones of India were purified, and six representative isolates (Pc-04, Pc-06, Pc-07, Pc-08, Pc-16 and Pc-20) were selected for detailed characterization. Significant morpho-cultural variability was observed across nine solid media, with TEA, V8J and OMA supporting maximum mycelial growth. Colony morphology, sporangial papillation, size and abundance varied among isolates. Physiologically, isolates differed markedly in pH and temperature responses, with optimum growth recorded between pH 5.5–8.0 and at 25–30 °C. Growth declined sharply below pH 4.5 and above pH 9.0, and no growth occurred at extreme temperatures (5–10 °C and 40 °C), although viability was retained upon shifting from cooler to permissive conditions. ITS-based phylogenetic analysis confirmed all isolates as P. cajani with high sequence similarity and discernible phylogenetic clustering with other Phytophthora spp. were also established. Fourteen pigeonpea genotypes found promising in previous studies, were screened against the six isolates under greenhouse conditions. Distinct differential reactions were recorded, with ICPL 99008 and ICPL 99009 showing consistent broad-spectrum resistance to all the isolates of P. cajani. Isolates Pc-04 and Pc-07 exhibited high aggressiveness, whereas Pc-16 and Pc-20 were comparatively less aggressive. This integrated analysis elucidates substantial diversity within P. cajani populations and identifies promising pigeonpea genotypes with stable resistance.
Vaibhav Srivastava, Mukesh Kumar, Meena et al.· Frontiers in Microbiology· 0 citations
Fusarium wilt, caused by Fusarium oxysporum f. sp. lycopersici, is a major constraint on tomato production worldwide. The present study was undertaken to evaluate thirty tomato germplasm accessions obtained from the ICAR-Indian Institute of Vegetable Research (IIVR), Varanasi, for their response to Fusarium wilt under field conditions during the 2023 and 2024 cropping seasons at SKUAST-Jammu, Chatha. The thirty germplasm accessions were evaluated under artificial disease pressure, and disease development was assessed through disease incidence, apparent infection rate (r), and area under the disease progress curve (AUDPC), with Pusa Ruby included as the susceptible cultivar. Significant variation was observed among the germplasm accessions in disease development and progression. Based on pooled disease incidence, one germplasm accession was categorised as tolerant (T), two as moderately susceptible (MS), ten as susceptible (S), and seventeen as highly susceptible (HS), whereas no germplasm accession showed resistant (R) or moderately resistant (MR) reactions. The germplasm accessions also exhibited considerable differences in infection rate and AUDPC values, reflecting variability in the speed and cumulative development of Fusarium wilt. Arka Saurabh exhibited comparatively lower disease development, while highly susceptible germplasm accessions showed rapid disease progression and greater disease accumulation. The identified tolerant and less susceptible germplasm accessions can be utilised as potential sources in tomato improvement programmes for developing Fusarium wilt-resistant cultivars.
Nentia Chib, S. K. Singh, M. Thabrez et al.· Plant cell biotechnology and...· 0 citations
Background
: High-tunnel tomato cultivation technology is vital for year-round production during the rainy season and for enhancing income among smallholder farmers in north-west Ethiopia. However, its productivity and sustainability are adversely affected by Fusarium wilt (FW) disease. This study assessed the current status of FW epidemics, examined associated biophysical factors, and characterized
Fusarium oxysporum f. sp. lycopersici
(FOL) isolates during the 2024 main cropping season.
Methods
: A total of 75 high-tunnel technologies were inspected in four major tomato-producing districts within two zones. A logistic regression model was used to associate biophysical factors with disease incidence and severity.
Results
: All the surveyed high-tunnels were infected with FW, with incidence ranging from 43.6% (Libo Kemkem) to 60.5% (Dera), and severity from 41.4% to 58.3%. Disease incidence and severity were strongly correlated (P < 0.001) with district, age and leakiness of high-tunnels, seed type and source, plant and weed density, crop rotation, and irrigation method. Elevated incidence and severity (>50%) were notably associated with Dera district, gray soils, older and leaky high-tunnels, local and unknown seed varieties, informal seed exchange, high plant and weed density, fruit-setting stage, absence of crop rotation, and contact irrigation method. Pathogen isolation and characterization study identified eight morpho-culturally and pathogenically diverse FOL isolates.
Conclusion
: FW exhibits extensive distribution across high-tunnel technologies, driven by various biophysical factors and has diverse strains. Therefore, integrated management strategies, including cultural interventions and resistant varieties, are imperative for sustainable high-tunnel tomato production in the study area. Further research on temporal pathogen dynamics and molecular characterization of isolates is also recommended.
Yekoye Abebaw, G. Damessa, E. Adgo et al.· CABI Agriculture and Bioscie...· 0 citations
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