Draft Genome Sequence and De Novo Assembly of a Fusarium oxysporum f. sp. lycopersici Isolate Collected from the Andean Region in Colombia

We report a draft genome assembly of the causal agent of tomato vascular wilt, Fusarium oxysporum f. sp. lycopersici isolate 59, obtained from the Andean region in Colombia.

Fusarium sp., causal agent of vascular wilt in citrus and its sensitivity to fungicides

<p>Citrus wilt is a disease of recent appearance in the northern area of Veracruz that causes economic losses to producers in the region. The present work aimed to identify the causative agent of this disease and evaluate different fungicides to determine its<em> in vitro</em> sensitivity. A fungus was consistently isolated in plants with wilt symptoms; it was morphologically identified indifferent culture media and molecularly identified by PCR using the EF1-728F/EF1-986R primers. The fungus was inoculated in three varieties of citrus under greenhouse conditions. The sensitivity test was carried out with the fungicides chlorothalonil, benomyl thiabendazole, prochloraz, and a biological agent (<em>Bacillus subtilis</em>) at different concentrations, plus a negative control. <em>Fusarium</em> sp. (Accession No. MW438335) was morphologically and molecularly identified as the causal agent of vascular wilt in citrus fruits, causing growth retardation, decreased number of roots, wilting of the apical bud, and necrosis in the vascular system of the three varieties inoculated. The most effective fungicides in inhibiting mycelial growth were thiabendazole, prochloraz, and the biological agent <em>Bacillus subtilis</em>.</p>

Molecular aspects of tomato (Solanum lycopersicum) vascular wilt by Fusarium oxysporum f. sp. lycopersici and antagonism by Trichoderma spp.

<p>Tomato plants (<em>Solanum lycopersicum</em>) are susceptible to the infection by diverse pathogens that cause devastating diseases such as vascular wilt, which causes great losses at the production level. The fungus <em>Fusarium oxysporum</em> f. sp. <em>lycopersici</em> (<em>Fol</em>) is one of the etiologic agents of this disease and its control lies in the use of synthetic chemicals which generate a negative impact in both health and the environment; thus, it is necessary to implement biological control as a healthier and more efficient alternative. The fungus <em>Trichoderma</em> spp. is a favorable option to be employed as a biocontroller against this pathogen thanks to its antagonist mechanisms, determined by metabolic and genetic characteristics. On the one hand, for <em>Fol</em> it is indispensable the activation of signaling routes such as MAPK Fmk1, MAPK Mpk1 y HOG, while <em>Trichoderma</em> spp. uses effectors involved in the interaction with the plant such as proteins, enzymes and secondary metabolites that also strengthen its immune response against infection, determined by both Pathogen Associated Molecular Patterns (PAMP) and effectors. Therefore, this article makes a review about the mentioned characteristics and suggests a greater application of tools and molecular markers for the management of this disease.</p>

Evaluation of the In Vitro Fungicidal Activity of Summer Savory and Lavender Essential Oils Against Fusarium solani

Fusarium spp is one of the major phytopathogenic microfungus strains causing severe losses in many economically cultivated crops. The soil-borne pathogen Fusarium solani has historically been considered a serious agent across the globe, causing vascular wilt and root rot in agroeconomic crops and eventually leading to plant death. Three different concentrations (1 µl, 2 µl, and 4 µl) of essential oils (EO) extracted from lavender (Lavandula officinalis L.) and summer savory (Satureja hortensis L.) plants were mixed separately with PDA medium, and their antifungal effect against F. solani was investigated in vitro. When the results of the experiment were evaluated statistically, it was determined that the increasing concentrations of summer savory essential oil repressed the mycelial growth of the fungus, while lavender oil did not have any positive or negative effects. The inhibition activity of summer savory EO on F. solani was calculated as 43, 53, and 90% at the concentrations of 1, 2, and 4 µl, respectively. In this study, it was found that summer savory EO, even at a minimum dose, had a negative effect on agriculturally important wilt agent. In this context, it can be asserted that summer savory EO is a promising natural substance for the development of various fungicide solutions to prevent fungal diseases caused by vascular origin.

Geographical Origin Does Not Modulate Pathogenicity or Response to Climatic Variables of Fusarium oxysporum Associated with Vascular Wilt on Asparagus

Asparagus crop is distributed worldwide, covering very different climatic regions. Among the different diseases that affect asparagus, vascular Fusarium wilt, caused by Fusarium oxysporum f. sp. aparagi (Foa), stands out. It is not only the cause of large economic losses due to a decrease in yield and shortened longevity of the plantation, but also prevents replanting. This work aimed to determine if F. oxysporum isolates associated with vascular wilt on asparagus have adapted differentially to the different agro-environmental conditions. The potential correlation between origin and mycelial growth under different temperatures and humidity conditions was analysed for isolates from asparagus fields cultivated in northern and southern Europe. The genetic and pathogenic variability were also analysed. While a clear effect of water activity on mycelial growth was observed, all isolates responded in a similar way to changes in water activity in the medium, regardless of their geographical origin. The results revealed a low genetic variability of F. oxysporum isolates associated with vascular wilt on asparagus without signs of differentiation correlated to geographical origin. The southernmost isolates of the two cultivated varieties inoculated did not express more pathogenicity than those isolated from the colder region.

Identification of Fusarium oxysporum f. sp. ciceris Physiological Races in Chickpea Cultivated Areas in Al-Ghab Region, Syria

Alloush, L., S. Al-Maghribi and B. Barhom. 2021. Identification of Fusarium oxysporum f. sp. ciceris Physiological Races in Chickpea Cultivated Areas in Al-Ghab Region, Syria. Arab Journal of Plant Protection, 39(4): 231-240. https://doi.org/10.22268/AJPP-39.4.231240 Fusarium wilt disease caused by Fusarium oxysporum f. sp. ciceris is one of the diseases that cause significant economic losses to the chickpea crop around the world, as infection with FOC can occurs during the different stages of plant growth. One of the best approaches to reduce the damage caused by FOC is by using resistant chickpea varieties. Hence, this study aimed to determine the physiological races of 25 FOC isolates collected from 20 agricultural sites belonging to six regulatory zones in the Al-Ghab region in Syria, based on their pathogenicity on 13 differential chickpea cultivars (C-104, JG -74, CPS-1, BG-215, BG-212, WR-315, Anniger, Chaffa, ILC482, L-550, K850-3/27, UC-27). The study was carried out during 2020 at the Agricultural Scientific Research Center in Al-Ghab. The results obtained showed that the tested isolates belong to races 0, 1B/C, 2, 3, 5, and 6. This is the first report of races 2 and 3 in Syria, and each of them constituted 28% of the total tested isolates, whereas 24% of the isolates were represented by race 0, and both races 5 and 1B/C occurred at 8% frequency, and race 6 included one isolate obtained from Abu Faraj site. Keywords: Chickpea, vascular wilt, physiological races, pathogenicity, Al-Ghab, Syria

Characterization of Fusarium Spp. Inciting Vascular Wilt of Tomato and Its Management by a Chaetomium-Based Biocontrol Consortium

Though the vascular wilt of tomato caused by the species of Fusarium is globally reported to be a complex disease in certain countries, for example, India, our studies indicated that the disease is caused by either Fusarium oxysporum f. spp. lycopersici (Fol) or Fusarium solani (FS) with the Fol being widely prevalent. In assessing the genetic diversity of 14 Fol strains representing the four Indian states by the unweighted pair group method with arithmetic averaging using Inter Simple Sequence Repeat (ISSR) amplicons, the strains distinguished themselves into two major clusters showing no correlation with their geographic origin. In pot experiments under polyhouse conditions, the seed dressing and soil application of a talc-based formulation of a biocontrol treatment, TEPF-Sungal-1 (Pseudomonas putida) + S17TH (Trichoderma harzianum) + CG-A (Chaetomium globosum), which inhibited Fol, was equally effective like the cell suspensions and was even better than the fungicidal mixture (copper oxychloride-0.25% + carbendazim-0.1%) in promoting the crop growth (52.3%) and reducing vascular wilt incidence (75%) over the control treatment, despite the challenge of inoculation with a highly pathogenic TOFU-IHBT strain. This was associated with significant expressions of the defense genes, indicating the induction of host resistance by a biocontrol consortium. In field experiments on two locations, the bioconsortium was highly effective in recording maximum mean fruit yields (54.5 and 60%) and a minimum mean vascular wilt incidence (37.5%) in comparison to the untreated control. Thus, Chaetomium-based bioconsortium demonstrated consistency in its performance across the two experiments in 2 years under the two field conditions.

Scarcity of Major Resistance Genes Against Verticillium Dahliae

Verticillium dahliae is a soil-borne fungal pathogen that causes vascular wilt disease in numerous plant species. The only described qualitative resistances against V. dahliae are the Ve1 gene and the V2 locus in tomato. These resistances have been overcome by virulent strains. We tried to identify additional resistances. Out of the methods we tested, comparing the canopy area of V. dahliae-inoculated plants with mock-inoculated plants yielded the best discriminative power in resistance tests. Out of six wild tomato accessions that were previously reported to possess some resistance, Solanum pimpinellifolium G1.1596 and S. cheesmanii G1.1615 displayed the lowest stunting and the least colonization by V. dahliae. Recombinant inbred line (RIL) populations were developed of both populations. No QTLs were identified in the G1.1596 RIL population. In the G1.1615 population, four small-effect QTLs were associated with reduced stunting. Many studies in other hosts also failed to discover major resistance genes against V. dahliae. We hypothesize that the scarcity of major resistance genes against V. dahliae is caused by its endophytic behaviour in nature. The limited damage in nature would not lead to evolutionary pressure to evolve major resistances. However, in agriculture V. dahliae can behave more pathogenic, leading to serious damage.

Susceptibility of the banana inflorescence to Blood disease

The bacterium Ralstonia syzygii subsp. celebesensis causes Blood disease of banana, a vascular wilt of economic significance in Indonesia and Malaysia. Blood disease has expanded its geographic range in the last 20 years and is an emerging threat to Southeast Asian banana production. Many aspects of the disease cycle and biology are not well understood, including the ability of different parts of the female and male inflorescence of banana to act as infection courts. This study confirms that the banana varieties of Cavendish, and Kepok ‘Kuning’ are susceptible to Blood disease and that an inoculum concentration of 102 CFU.mL-1 of R. syzygii subsp. celebesensis is adequate to initiate disease following pseudostem inoculation. Data show that infection occurs through both the male and female parts of a banana inflorescence and the rachis when snapped to remove the male bell. The infection courts are the female flowers, the male bell bract scar, the male bell flower cushion, the snapped rachis, and deflowered fingers. The location of these infection courts concurs with the dye studies demonstrating that dye externally applied to these plants parts enters the plant vascular system. Thus, the hypothesis is supported that infection of R. syzygii subsp. celebesensis occurs through open xylem vessels of the male and female parts of the banana inflorescence.