Figure 7 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Pycnidia of Leptosphaeria maculans (lower portion of stem) and microsclerotia of Verticillium longisporum (upper portion) occurring on the same canola stem (a). Cross-sections of canola stems showing the discoloration caused by Verticillium stripe (left) and blackleg (right) (b).
Source publication
Blackleg, caused by Leptosphaeria maculans, is an important disease of canola (Brassica napus). The pathogen can attack stems, leaves and pods, but basal stem cankers are most damaging and can result in significant yield losses. In Canada, Verticillium stripe (Verticillium longisporum) has recently emerged as another disease threat to canola. Sympt...
Contexts in source publication
Context 1
... the symptoms and signs of blackleg and Verticillium stripe were superficially similar, they could readily be distinguished with careful examination, even when they occurred together. The microsclerotia of V. longisporum were much smaller than the pycnidia produced by L. maculans and were greyer in color (Figure 7a). Due to their larger size, individual pycnidia could be discerned more easily, and were generally more darkly pigmented than the microsclerotia. ...
Context 2
... to their larger size, individual pycnidia could be discerned more easily, and were generally more darkly pigmented than the microsclerotia. Moreover, while both V. longisporum and L. maculans caused a vascular discoloration visible in cross-sections of the crown or base of the stem, the staining associated with blackleg was darker (black) and more discrete than the grey, more diffuse staining resulting from Verticillium stripe (Figure 7b). Longitudinal sections of the stem further served to distinguish the two diseases. ...
Similar publications
En Uruguay, se ha incursionado poco en esta rama del Control Biológico. Estudios recientes enmarcados en el desarrollo de una tesis doctoral en la Universidad de la Habana-Cuba, y con los trabajos de investigación llevados a cabo en sistemas de producción orgánica e integrada, brindan resultados promisorios en este campo. Actualmente, nuevas invest...
The diversity and stability of belowground microbiota communities influence plant health. However, changes over time in the microbiome composition associated with healthy and diseased trees remains poorly understood. The goal of this study is to understand the changes in belowground microbial community associated with Verticillium wilt of smoke tre...
Verticillium wilt (VW) is often referred to as the cancer of cotton and it has a detrimental effect on cotton yield and quality. Since the root system is the first to be infested, it is feasible to detect VW by root analysis in the early stages of the disease. In recent years, with the update of computing equipment and the emergence of large-scale...
The hazardous pest known as rice leaf roller (Marasmia ruralis Wlk.) (Lepidoptera: Pyralidae), which undermines rice (Oryza sativa L.) output globally, folds the leaves of the rice plant. Protein elicitors are thought to be biological elements that causes the rice to become resistant to herbivores. The potential for biocontrol of the emerging elici...
Citations
... Verticillium stripe severity was evaluated at plant maturity on a 0 to 4 scale, based on the amount of fungal microsclerotia on the entire plant, as described by Wang et al. [17]. Briefly, a rating of 0 = healthy plants with no microsclerotia visible; 1 = slight colonization by microsclerotia < 25%; 2 = moderate colonization by microsclerotia ≥ 25% to <75%; 3 = extensive colonization by microsclerotia ≥ 75%; 4 = severe colonization by microsclerotia and peeling of the stem epidermis. ...
Verticillium stripe, caused by Verticillium longisporum, is an emerging disease of canola (Brassica napus) in Canada. Studies were conducted to assess the impact of pH on both the growth of V. longisporum and its virulence on the canola host. Fungal growth was assessed by measuring the colony diameter following 14 and 21 days of incubation on potato dextrose agar at varying pH levels (4.7, 5.5, 6.5, 7.4, or 8.6). The results indicated that colonies of V. longisporum were approximately 16% greater in diameter at pH 7.4 and 8.6 compared with those at pH 5.5. The impact of pH on disease development at the seedling stage was investigated using a semi-hydroponic system with different pH levels of 4.4, 5.4, 6.3, 7.5, and 8.4 in half-strength Hoagland’s solution. Verticillium stripe was most severe at pH 7.5 and 8.4 after a 10-day period in the semi-hydroponic system. In a second inoculation experiment, canola seedlings previously inoculated with the fungus were transplanted into potting mix amended to four pH levels (5.6, 6.4, 7.2, and 7.8). The transplants were cultivated under greenhouse conditions and evaluated for Verticillium stripe severity at plant maturity. Disease severity was greatest at pH 7.8. This is the first study on the effects of pH on V. longisporum in canola. It suggests a substantial risk of increased disease severity and yield losses due to Verticillium stripe in regions with neutral to slightly alkaline soils.
... upon the availability of suitable environmental conditions [10]. Disease symptoms develop with an increasing amount of pathogen-colonized rapeseed root and shoot tissues [11,12]. However, it is difficult to distinguish the disease symptoms from natural senescence due to premature crop ripening caused by V. longisporum. ...
Priming plants with beneficial microbes can establish rapid and robust resistance against numerous pathogens. Here, compelling evidence is provided that the treatment of rapeseed plants with Trichoderma harzianum OMG16 and Bacillus velezensis FZB42 induces defence activation against Verticillium longisporum infection. The relative expressions of the JA biosynthesis genes LOX2 and OPR3, the ET biosynthesis genes ACS2 and ACO4 and the SA biosynthesis and signalling genes ICS1 and PR1 were analysed separately in leaf, stem and root tissues using qRT-PCR. To successfully colonize rapeseed roots, the V. longisporum strain 43 pathogen suppressed the biosynthesis of JA, ET and SA hormones in non-primed plants. Priming led to fast and strong systemic responses of JA, ET and SA biosynthesis and signalling gene expression in each leaf, stem and root tissue. Moreover, the quantification of plant hormones via UHPLC-MS analysis revealed a 1.7- and 2.6-fold increase in endogenous JA and SA in shoots of primed plants, respectively. In roots, endogenous JA and SA levels increased up to 3.9- and 2.3-fold in Vl43-infected primed plants compared to non-primed plants, respectively. Taken together, these data indicate that microbial priming stimulates rapeseed defence responses against Verticillium infection and presumably transduces defence signals from the root to the upper parts of the plant via phytohormone signalling.
Plant defense responses to the soil-borne fungus Verticillium longisporum causing stem stripe disease on oilseed rape (Brassica napus) are poorly understood. In this study, a population of recombinant inbred lines (RILs) using the Arabidopsis thaliana accessions Sei-0 and Can-0 was established. Composite interval mapping, transcriptome data and T-DNA mutant screening identified the NITRATE/PEPTIDE TRANSPORTER FAMILY 5.12 gene (AtNPF5.12) as being associated with disease susceptibility in Can-0. Coimmunoprecipitation revealed interaction between AtNPF5.12 and the MAJOR LATEX PROTEIN family member AtMLP6, and fluorescence microscopy confirmed interaction in the plasma membrane and endoplasmic reticulum. CRISPR/Cas9 technology was applied to mutate the NPF5.12 and MLP6 genes in B. napus. Elevated fungal growth in the npf5.12 mlp6 double mutant of both oilseed rape and Arabidopsis demonstrated their importance in defense against V. longisporum. Colonization of this fungus depends also on available nitrates in the host root. Accordingly, the negative effect of nitrate depletion on fungal growth was less pronounced in Atnpf5.12 plants with impaired nitrate transport. In addition, suberin staining revealed involvement of the NPF5.12 and MLP6 genes in suberin barrier formation. Together, these results demonstrate a dependency of multiple plant factors that lead to successful V. longisporum root infection.
