Isolation and evaluation of endophytic Streptomyces endus OsiSh-2 with potential application for biocontrol of rice blast disease.
BACKGROUND
Biocontrol is a promising strategy in the control of rice blast disease. In the present study, we isolated and characterized a novel antagonist to the pathogen Magnaporthe oryzae from rice endophytic actinomycetes.


RESULTS
Out of 482 endophytic actinomycetes isolated from rice blast infected and healthy rice, Streptomyces endus OsiSh-2 exhibited remarkable in vitro antagonistic activity. Scanning electron microscopy observations of M. oryzae treated by OsiSh-2 revealed significant morphological alterations in hyphae. In 2-year field tests, the spraying of OsiSh-2 spore solution (107spores mL-1) is capable of reducing rice blast disease severity by 59.64%. In addition, a fermentation broth of OsiSh-2 and its cell-free filtrates could inhibit the growth of M. oryzae, suggesting the presence of active enzymes and secondary metabolites. OsiSh-2 tested positive for polyketide synthase-I and nonribosomal peptide synthetase genes and can produce cellulase, protease, gelatinase, siderophore, indole-3-acetic acid and 1-amino-cyclopropane-1-carboxylate deaminase. A preliminary separation indicated that the methanol extract of OsiSh-2 could suppress the growth of pathogens. The major active component was identified as nigericin.


CONCLUSIONS
Endophytic S. endus OsiSh-2 has potential as a biocontrol agent against rice blast in agriculture. © 2016 Society of Chemical Industry.
Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, Hunan, PR China.
Ting
T
Xu
Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, Hunan, PR China.
Yan
Y
Li
Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, Hunan, PR China.
Xiadong
X
Zeng
Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, Hunan, PR China.
Xiaolu
X
Yang
Yahua Seeds Science Academy of Hunan, Changsha, 410119, Hunan, PR China.
Yuanzhu
Y
Yang
Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, Hunan, PR China.
Shanshan
S
Yuan
Yahua Seeds Science Academy of Hunan, Changsha, 410119, Hunan, PR China.
Xiaochun
X
Hu
Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, Hunan, PR China.
Jiarui
J
Zeng
Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, Hunan, PR China.
Zhenzhen
Z
Wang
Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, Hunan, PR China.
Qian
Q
Liu
Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, Hunan, PR China.
Yuqing
Y
Liu
Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, Hunan, PR China.
Hongdong
H
Liao
Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, Hunan, PR China.
Chunyi
C
Tong
Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, Hunan, PR China.
Xuanming
X
Liu
Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, Hunan, PR China.
Yonghua
Y
Zhu
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D061046:Biological Control Agents / Q000737:chemistry / Q000494:pharmacology*; D003470:Culture Media; D060026:Endophytes / Q000737:chemistry / Q000201:enzymology / Q000302:isolation & purification; D005285:Fermentation; D005374:Filtration; D005659:Fungicides, Industrial / Q000737:chemistry / Q000494:pharmacology*; D005798:Genes, Bacterial; D025301:Hyphae; D007210:Indoleacetic Acids / Q000378:metabolism; D020082:Magnaporthe / Q000187:drug effects* / Q000472:pathogenicity; D009550:Nigericin / Q000032:analysis / Q000494:pharmacology; D012275:Oryza / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology*; D017262:Siderophores / Q000378:metabolism; D013171:Spores, Bacterial; D013302:Streptomyces / Q000737:chemistry / Q000201:enzymology / Q000302:isolation & purification
D001426:Bacterial Proteins; D061046:Biological Control Agents; D003470:Culture Media; D005659:Fungicides, Industrial; D007210:Indoleacetic Acids; D017262:Siderophores; C030737:indoleacetic acid; D009550:Nigericin
Magnaporthe oryzae; Streptomyces endus OsiSh-2; antagonistic agents; rice blast; rice endophytes