Evaluation of Biocontrol Activities of Streptomyces spp. against Rice Blast Disease Fungi.

Mathurot Chaiharn,Teerayut Theantana,Wasu Pathom-Aree

doi:10.3390/pathogens9020126

Mathurot Chaiharn, Teerayut Theantana + Show 1 more

Open Access

https://doi.org/10.3390/pathogens9020126

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Abstract

Rhizosphere bacteria can positively influence plant growth by direct and indirect mechanisms. A total of 112 bacterial strains were isolated from the rhizosphere of rice and tested for plant beneficial activities such as siderophore production, cell-wall-degrading enzyme production, hydrogen cyanide (HCN) production and antifungal activity against rice blast disease fungus. The actinomycetes count was 3.8 × 106 CFU/g soil. Streptomyces strains PC 12, D 4.1, D 4.3 and W1 showed strong growth inhibition of blast disease fungus, Pyricularia sp. (87.3%, 82.2%, 80.0% and 80.5%) in vitro. Greenhouse experiments revealed that rice plants treated with Streptomyces strain PC 12 recorded maximum plant height, root length and root dry weight compared to the control. Taxonomic characterization of this strain on the basis of 16S rRNA gene sequence led to its identification as Streptomyces palmae PC 12. Streptomyces palmae PC 12 may be used as biofertilizer to enhance the growth and productivity of commercially important rice cultivar RD6 and the biocontrol of blast disease fungus.

Highlights

Rice (Oryza sativa) is an important food crop and it is the staple diet of people around the world, especially in Asia
Rhizosphere Streptomyces in this study showed antagonistic activity against the rice blast fungus, Pyricularia sp., which correlated with their ability to produce siderophores, hydrolytic enzymes and antibiotics (Table 2)
It is evident that selected rhizosphere actinomycetes successfully suppressed or reduced disease symptoms under both in vitro and in vivo greenhouse conditions

Summary

Introduction

Rice (Oryza sativa) is an important food crop and it is the staple diet of people around the world, especially in Asia. The germinated spores produce an extracellular matrix (ECM), and firmly attach to the plant surface [4]. The attached spores develop a germination tube, an aspersorium and a penetration peg, and complete infection by signal exchange with the host plant via ECM [4]. The fungus can infect rice plants at any growth stage and infects the aerial parts of rice including leaves, nodes, stems and panicles [2,3,7]. Rice blast symptoms include leaf blast, node blast, collar rot, neck rot and panicle blast, which manifests as grayish/brownish spots or lesions as well as the withering of leaves [2,3,8]

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