Pathogenicity and Ultrastructural Studies of the Mode of Penetration by Phoma strasseri in Peppermint Stems and Rhizomes

Abstract

Pathogenicity and ultrastructural investigation of the inoculation of peppermint stems and rhizomes with Phoma strasseri conidia was undertaken using scanning and transmission electron microscopy to examine the host-parasite relationship. Pathogenicity experiments demonstrated that all tested P. strasseri isolates had infected the stems and rhizomes of peppermint. Of all inoculation methods, direct placement of colonized agar plugs on damaged epidermis and soaking stems and rhizomes in conidial suspension were the most effective. The behavior of the conidia deposited on the stems and rhizomes was investigated at different time intervals after inoculation: 6, 16, 24, 36 and 48 h. Conidia produced an appressorium directly at the end of a short germ tube. Appressoria were formed over the cuticle, but never over stomata. Direct penetration to host tissue through the cuticle was observed. The spore and hyphae were covered with a mucilaginous sheath.

Molecular characterization of Boeremia strasseri the causal agent of black stems and rhizomes rot of peppermint

“…The Boeremia isolates have previously been used to study their morphological features following the methods described by Boerema et al (2004). Some of these isolates were also examined for pathogenicity to peppermint stems and rhizomes (Zimowska and Machowicz-Stefaniak 2005;Zimowska 2012). Single spore cultures of these isolates were grown on 2% malt extract agar plates (MEA; Difco Laboratories, USA).…”

“…The disease causes yield losses up to 90% due to the fast degradation of stem and rhizome tissues. A very high activity of β-glucosidase allows B. strasseri to penetrate the host cell wall and tissues, followed by the action of other pectinolityc enzymes that break down pectin to low molecular weight compounds, which are the primary source of carbon for the pathogen (Zimowska 2012;Zimowska and Targoński 2015).…”

The Genus Phoma: What We Know and What We Need to Know?

“…The genus Phoma occurs ubiquitously as phytopathogens, saprophytes, endophytes and aquatic, air and also human and animal pathogens (Rai 1989;Aveskamp et al 2008;de Gruyter et al 2009;Kövics et al 2013;Kukhar et al 2020). Majority of Phoma species parasitize on plants (mainly leaves and stems) including medicinal and aromatic plants which is responsible for huge loss (Zimowska 2007a(Zimowska , b, 2008(Zimowska , 2012. It has been reported globally on different hosts/substrates.…”

“…The results of 40 years of taxonomic research based on the properties of Phoma species were presented in articles concerning their identification, and as a consequence, the number of species was reduced to 223 (Boerema et al 2004). The highly phylogenetic heterogeneity of the species in the Phoma sections negated the existing division of the genus into sections and caused the necessity to reclassify (De Gruyter et al 2009, 2012Aveskamp et al 2010). That conventional taxonomical system based on morphological features in in vitro conditions is still valid but insufficient because the absence of outstanding differences in conidial characters and moreover micromorphological features depend on strains, place of origin and host plants.…”

Phoma on Medicinal and Aromatic Plants

“…Many are recognized as important quarantine species, posing a threat to a diverse range of crops (Aveskamp et al 2010). Terrestrial fungi belonging to Phoma sensu lato are well-known phytopathogens of medicinal and aromatic plants (MAPs), causing significant loses in commercial crops (Zimowska 2007a(Zimowska , b, 2008(Zimowska , 2012. They also inhabit tissue of the mentioned group of plants as saprotrophic and endophytic species (Nicoletti and Fiorentino 2015;Chen et al 2020).…”