Cold plasma as a novel treatment to reduce the in vitro growth and germination of Colletotrichum species

Abstract

This study investigated the use of cold plasma to reduce the in vitro growth of two postharvest fungal plant pathogens, Colletotrichum alienum and C. fioriniae, isolated from avocados. Cold plasma (CP) was used to treat pure cultures and conidial suspensions of both pathogens, for 180 or 360 s, in either open or sealed environments from varying distances. In an open environment, the 360 s treatment at a distance of 5 cm reduced the colony growth of freshly inoculated cultures to less than 2 mm/day compared to the control of more than 8 mm/day, and treatment of conidial suspensions resulted in almost 100% reduction of conidial germination. In the same environment, the 180 s CP treatment did not significantly reduce the colony growth of fresh or actively growing cultures, but did suppress the germination of conidia by up to 80%. In a sealed environment, the 360 s CP treatment also effectively reduced the growth of freshly inoculated cultures, with no growth for some isolates. Production of reactive oxygen and nitrogen species was observed during treatment, and these may have contributed to the reduction in growth and germination. These results demonstrate the potential of CP for the control of two Colletotrichum species.

Effects of non‐thermal plasma technology on Diaporthe longicolla cultures and mechanisms involved

“…Similar results were obtained by Go et al 50 . and Siddique et al 17 . working with Fusarium oxysporum and Colletotrichum species, respectively.…”

“…Fungal growth inhibition coincided with diminished mycelial fresh weight (Table 2), which was significantly lower in both NTP treatments, TN3 and TO3, compared with control colonies. Similar results were obtained by Go et al 50 and Siddique et al 17 working with Fusarium oxysporum and Colletotrichum species, respectively. The oxidative power of NTP, due to the production of ROS and RNS, has been extensively demonstrated, as has the ability of plasma to destroy microbial cells through oxidative damage.…”

“…11,[13][14][15] Nevertheless, the mechanisms of inactivation are still being intensively explored and discussed. 16,17 Although each reactive substance can affect cells independently, it has been suggested that inactivation of microorganisms results from their synergistic effects. 18 Thereby, NTP may exhibit different modes of action: cell surface erosion, 19,20 lipid peroxidation, [20][21][22] enzyme activity alteration, 20,23 protein denaturation, 19,24 and DNA degradation.…”

Plasma‐activated water inhibits in vitro conidial germination of Colletotrichum alienum, a postharvest pathogen of avocado

“…A conidial suspension of C. alienum isolate WAC-13891, previously demonstrated to be strongly pathogenic on avocado, was prepared as described by Siddique et al (2019).…”

“…To produce PAW, water was treated with CP produced with a Dyne-A-Mite HP (Enercon) in a fume hood using air as the feed gas, as described for the treatment of conidial suspensions by Siddique et al (2019), but with the plasma emission point set at a fixed distance from the water surface ( Figure 1a). CP treatment duration was 30 min to produce PAW30, or 60 min to produce PAW60.…”