Suppressive Effect of Bioactive Extracts of Bacillus sp. H8-1 and Bacillus sp. K203 on Tomato Wilt Caused by Clavibacter michiganensis subsp. michiganensis.

Hwajin Jang,Mee Kyung Sang,Sang Tae Kim

doi:10.3390/microorganisms10020403

Hwajin Jang, Mee Kyung Sang + Show 1 more

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https://doi.org/10.3390/microorganisms10020403

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Journal: Microorganisms	Publication Date: Feb 9, 2022
Citations: 6	License type: CC BY 4.0

Affiliation: Rural Development Administration

Abstract

Tomatoes are cultivated worldwide, and are economically important. Clavibacter michiganensis subsp. michiganensis (Cmm) is a pathogen that causes canker and wilting in tomatoes, resulting in serious damage to tomato plants. We aimed to control Cmm proliferation using substances produced by useful microorganisms. The water extracts of strains H8-1 and K203 inhibited wilting caused by Cmm and slowed the pathogenic colonization in tomato plants. The relative expressions of celA, celB, pat1, and pelA of Cmm treated with the bacterial water extracts were reduced by 0.41-, 0.01-, 0.15-, and 0.14-fold for H8-1, respectively, and 0.45-, 0.02-, 0.13-, and 0.13-fold for K203, respectively, compared to controls at 72 h after treatments. In tomato plants inoculated with Cmm, when water extracts of H8-1 and K203 were treated, relative expression of ACO encoding 1-aminocyclopropane-1-carboxylic acid oxidase was suppressed by 0.26- and 0.23-fold, respectively, while PR1a was increased by 1.94- and 2.94-fold, respectively; PI2 expression was increased by 3.27-fold in water extract of H8-1-treated plants. As antioxidant enzymes of plants inoculated with Cmm, peroxidase and glutathione peroxidase levels were increased in K203-water-extract-treated plants, and catalase was increased in the case of the H8-1 water extract at 10 days after inoculation. In terms of soil enzyme activity, each water extract tended to increase urease activity and microbial diversity; in addition, K203 water extract increased plant growth. Thus, H8-1 and K203 water extracts can be used as potential biocontrol agents against Cmm.

Highlights

Tomatoes are the second most important crop in the world, with a total output of 182 million tons [1,2]
We investigated the mode of action of the bacterial extracts from various perspectives including Clavibacter michiganensis subsp. michiganensis (Cmm) colonization and pathogenicityrelated gene expression, plant antioxidant response and gene expression, and soil activities, by studying total microbial activity, phosphatase and urease activities, and diversity, based on the use of 31 carbon sources
The bacterial pathogen, Clavibacter michiganensis subsp. michiganensis (Cmm, KACC 16995), was grown on nutrient broth yeast extract agar (NBYA) medium (8 g of nutrient broth, 2 g of yeast extract, 2.5 g of glucose, 2 g of KH2 PO4, 0.5 g of KH2 PO4, 1.5 g of MgSO4 ·7H2 O, and 15 g of agar per liter) at 28 ◦ C for 3 days [32], and a single colony was propagated in nutrient broth yeast extract broth (NBY) at 28 ◦ C and 160 rpm for 24 h

Summary

Introduction

Tomatoes are the second most important crop in the world, with a total output of 182 million tons [1,2]. Michiganensis (Cmm) is a soil-borne bacterial pathogen that reduces tomato yield and quality, resulting in significant economic losses [3,4,5,6]. Most soil pathogens are Gram-negative, whereas Cmm is a Gram-positive bacterium belonging to Actinomyces that causes significant crop losses by causing wilt and canker disease in tomato plants [7,8,9,10]. Cmm systemically infects host plants through wounds, pores, and seeds, causing wilt and canker symptoms [7]. When Cmm infects the early stages of host plants, they develop systemic infections, referred to as primary infections, which affect the quality and harvest of fruits, and generally cause death.

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