Menadione Sodium Bisulfite-Protected Tomato Leaves against Grey Mould via Antifungal Activity and Enhanced Plant Immunity

Vapours from plant essential oils to manage tomato grey mould caused by Botrytis cinerea

Tomato grey mould has been a great concern during tomato production. The in vitro antifungal activity of vapours emitted from four plant essential oils (EOs) (cinnamon oil, fennel oil, origanum oil, and thyme oil) were evaluated during in vitro conidial germination and mycelial growth of Botrytis cinerea, the causal agent of grey mould. Cinnamon oil vapour was the most effective in suppressing conidial germination, whereas the four EOs showed similar activities regarding inhibiting mycelial growth in dose-dependent manners. The in planta protection effect of the four EO vapours was also investigated by measuring necrotic lesions on tomato leaves inoculated by B. cinerea. Grey mould lesions on the inoculated leaves were reduced by the vapours from cinnamon oil, origanum oil and thyme oil at different levels, but fennel oil did not limit the spread of the necrotic lesions. Decreases in cuticle defect, lipid peroxidation, and hydrogen peroxide production in the B. cinerea-inoculated leaves were correlated with reduced lesions by the cinnamon oil vapours. The reduced lesions by the cinnamon oil vapour were well matched with arrested fungal proliferation on the inoculated leaves. The cinnamon oil vapour regulated tomato defence-related gene expression in the leaves with or without fungal inoculation. These results suggest that the plant essential oil vapours, notably cinnamon oil vapour, can provide eco-friendly alternatives to manage grey mould during tomato production.

Characterization of a new Bacillus velezensis as a powerful biocontrol agent against tomato gray mold

Biocontrol microbes are environment-friendly and safe for humans and animals. To seek biocontrol microbes effective in suppressing tomato gray mold is important for tomato production. Therefore, serial experiments were conducted to characterize the antagonism of Bacillus velezensis HY19, a novel self-isolated biocontrol bacterium, against Botrytis cinerea in vitro and the control on tomato gray mold in greenhouse. This bacterium produced extracellular phosphatase, protease, cellulose and siderophores, and considerably inhibited the growth of B. cinerea. A liquid chromatography-mass spectrometry (LC-MS) detected salicylic acid and numerous antifungal substances present in B. velezensis HY19 fermentation liquid (BVFL). When B. cinerea was grown on potato glucose agar, BVFL crude extract remarkably suppressed the fungal growth and reduced protein content and the activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD). Transcriptome studies showed that BVFL crude extract significantly induced different expression of numerous genes in B. cinerea, most of which were down-regulated. Theses differently expressed genes were involved in the biological process, cell compartment, molecular functions, and metabolisms of glycine, serine, threonine, and sulfur in pathogen hyphae. Thus, this biocontrol bacterium antagonized B. cinerea in multiple ways due to the production of numerous antifungal substances that acted on multiple targets in the cells. BVFL significantly increased antioxidant enzyme activities in tomato leaves and decreased the incidence of tomato gray mold, with the control efficacies of 73.12-76.51%. Taken together, B. velezensis HY19 showed a promising use potential as a powerful bioagent against tomato gray mold.

Root treatment with a vitamin K3 derivative: a promising alternative to synthetic fungicides against Botrytis cinerea in tomato plants

BACKGROUND

Botrytis cinerea, the causal agent of gray mold has a great economic impact on several important crops. This necrotrophic fungus causes disease symptoms during vegetative growth and also into postharvest stages. The current method to combat this disease is fungicide application, with high economic costs and environmentally unsustainable impacts. Moreover, there is an increasing general public health concern about these strategies of crop protection. We studied the protection of tomato plants against B. cinerea by previous root treatment with menadione sodium bisulfite (MSB), a known plant defense activator.

RESULTS

Root treatment 48 h before inoculation with MSB 0.6 mmol L^-1 reduced leaf lesion diameter by 30% and notably cell deaths, compared to control plants 72 h after inoculation. We studied the expression level of several pathogenesis-related (PR) genes from different defense transduction pathways, and found that MSB primes higher PR1 expression against B. cinerea. However, this stronger induced resistance was impaired in transgenic salicylic acid-deficient NahG line. Additionally, in the absence of pathogen challenge, MSB increased tomato plant growth by 28% after 10 days. Our data provide evidence that MSB protects tomato plants against B. cinerea by priming defense responses through the salicylic acid (SA)-dependent signaling pathway and reducing oxidative stress.

CONCLUSION

This work confirms the efficacy of MSB as plant defense activator against B. cinerea and presents a novel alternative to combat gray mold in important crops.

A Beginner's Guide to Osmoprotection by Biostimulants

Water is indispensable for the life of any organism on Earth. Consequently, osmotic stress due to salinity and drought is the greatest threat to crop productivity. Ongoing climate change includes rising temperatures and less precipitation over large areas of the planet. This is leading to increased vulnerability to the drought conditions that habitually threaten food security in many countries. Such a scenario poses a daunting challenge for scientists: the search for innovative solutions to save water and cultivate under water deficit. A search for formulations including biostimulants capable of improving tolerance to this stress is a promising specific approach. This review updates the most recent state of the art in the field.