Evaluation of virulence and pathogenicity of Alternaria patula on French marigold (Tagetes patula)

Abstract

Alternaria patula, the cause of French marigold leaf black spot and flower blight, was first isolated from seeds of French marigold cv. Queen Sophia. It is described as a new species of Alternaria and has a considerable morphological variation with a preferential pathogenicity to Asteraceae, Solanaceae and Cucurbitaceae plants. Alternaria patula produces an array of pectin depolymerases that can break 1,4-a-glycosidic bonds either by hydrolysis of polygalacturonases (PG, E.C. 3.2.1.15) or via trans-elimination of pectate lyases (PL, E.C. 4.2.2.2) and pectin lyases (PNL, E.C. 4.2.2.10). This study is the first to emphasize the variability and significance to pathogenesis of the pectinolytic enzymes of A. patula that target various pectic polymers structures during host tissue invasion. Alternaria patula also produced zinniol derivatives as non-host-specific toxins (nHSTs), albeit without phytotoxic symptoms in French marigold. The management of Alternaria blight caused by A. patula via the application of pyrifenox and antagonistic Bacillus amyloliquefaciens effectively reduced disease severity, without adverse effects on French marigold in both in vitro and in vivo bioassays.

The characteristics, occurrence, and toxicological effects of alternariol: a mycotoxin

“…However, spore infection and germination can occur within a wide temperature range of between 4 and 35 °C (Chain 2011 ). During infection, Alternaria species produce host-specific, and non-host-specific phytotoxins and extracellular enzymes to destroy plant cell walls at the infection site, which plays a major role in pathogenicity against plants (Wu and Wu 2019 ). Due to their tolerance to wide environmental conditions, Alternaria can infect a range of produce in various geographic locations, which cause the propagation of its mycotoxins (Louro et al 2024 ).…”

Alternaria in berry: Effects on its quality, pathogenic mechanisms and potential control strategies

“…It is therefore assumed that Alternaria can grow and reproduce around the world, although there is no direct report of this (Blagojević et al., 2020; Yin et al., 2021). In addition, some studies have shown that Alternaria can produce a variety of toxins, which can be divided into host‐selective toxins (HST) and non‐host‐selective toxins (nHST) (Wu & Wu, 2019). Among them, HSTs play a role in plant pathogenicity, while nHSTs can also play important roles in relation to host ranges (causing symptoms on multiple other plant species) and may not be essential for pathogenicity, but may contribute to virulence, posing a threat to the edible safety of berries (Meena & Samal, 2019; Wang, Guo, Luo, et al., 2022).…”

Diversity and pathogenicity of Alternaria species associated with the invasive plant Ageratina adenophora and local plants

“…Alternaria is widely distributed and commonly occurs as saprophytes, endophytes and pathogens ( Nishikawa & Nakashima, 2020 ). More than 95% of Alternaria species have a wide range of plant pathogens that can cause a variety of diseases in many economically important crops or ornamental plants, e.g ., early blight in potato and tomato ( Kokaeva et al, 2017 ), black spot and leaf spot in wheat ( Vergnes et al, 2006 ), and leaf spot in cruciferous ( Al-Lami, You & Barbetti, 2018 ), Solanaceae ( Liu et al, 2019 ) and Asteraceae ( Wu & Wu, 2018 ). Therefore, caution should be taken regarding the possible ecological risk in disease transmission on local plants driven by A. adenophora invasion.…”