Volatile organic compounds (VOCs) from Bacillus subtilis CF-3 reduce anthracnose and elicit active defense responses in harvested litchi fruits

Abstract

In this study, we investigated the effects of volatile organic compounds (VOCs) produced by Bacillus subtilis CF-3 on the growth and development of Colletotrichum gloeosporioides and evaluated the elicitation of active defense responses in harvested litchi fruits. In vitro experiments were conducted to explore the bacteriostatic effect of VOCs in inhibiting pathogenic fungi by means of plate enthalpy test, scanning electron microscopy, transmission electron microscopy, and gas chromatography–mass spectrometry (GC–MS). The results showed that 2,4-di- tert -butylphenol and CF-3 24-h fermentation broth (24hFB) can significantly inhibit the germination of fungal spores, disrupt hyphal and cell morphology, and decrease cell membrane fluidity and integrity, resulting in the changes of indexes. In addition, the bacteriostasis of VOCs in the defensive ability of litchi fruits to C. gloeosporioides was studied, and it was shown that 2,4-di- tert -butylphenol and CF-3 24hFB can inhibit the activity of the pathogenic enzymes (pectinase and cellulase) secreted by C. gloeosporioides to reduce the decomposition of plant tissues, activate antioxidant enzymes (peroxidase, polyphenol oxidase, catalase, and superoxide dismutase) in the fruit to eliminate excessive reactive oxygen species in fruits in order to reduce plant cell damage and activate disease resistance enzymes (phenylalanineammonialyase, chitinases, β-1,3-glucanase) to enhance the resistance of litchi fruits to C. gloeosporioides and inhibit its growth. This study investigated the bacteriostasis of VOCs in inhibiting C. gloeosporioides and inducing the resistance of litchi fruits, providing a theoretical basis for future applications.

The inhibitory effect of volatile organic compounds produced by Bacillus subtilis CL2 on pathogenic fungi of wolfberry

“…could inhibit the fungal hyphal growth, spore germination, and germ tube elongation [18,28]. In another study, VOCs released by B. subtilis could act on the cell wall and the cell membrane system of fungi, destroying their basic functions [29]. In this experiment, the SEM results confirmed this conclusion.…”

“…Bacillus is also used as a biological control bacteria for postharvest preservation of fruits [31,32]. The VOCs produced by B. subtilis CF-3 can inhibit the growth of peach fruit pathogen Monilinia fructicola and reduce the anthracnose content in harvested litchi fruits by modifying the hyphal and cell morphology and destroying the integrity of the membrane of the pathogen [29,33]. In an in vivo experiment, the VOCs produced by B. subtilis CL2 could significantly reduce the incidence rate of decay and the weight loss rate of wolfberry caused by a pathogenic fungus.…”

Plant Growth-Promoting Bacteria Associated with the Nests of the Seed-Harvester Ant, Trichomyrmex Scabriceps

“…These results support earlier ndings which show similar pattern of higher production of defensive chemical compounds such as lignin and phenol due to the effects of rhizobacteria on S. rolfsii challenged plants [40,41]. The higher PO enzyme production may be related to the reduction in reactive oxygen species level that gets accumulated due to pathogen infection [42].…”

Nematicidal Volatiles from Bacillus atrophaeus GBSC56 Promote Growth and Stimulate Induced Systemic Resistance in Tomato against Meloidogyne incognita

“…The antioxidant enzymatic system plays a significant role in plant resistance against different pathogens, minimizing the adverse effect of ROS induced after infection [50]. Previously, the volatiles produced by Bacillus subtilis CF-3 reduced the disease progression of Colletotrichum gloeosporioides on the harvested lychee fruits and positively regulated the antioxidant enzymes activity of fruits to minimize the adverse effect of oxidative stress induced after infection [51]. Studies conducted in the past also reported an upsurge in the antioxidant enzymes activity of plants infected with phytopathogenic bacteria [52].…”