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journal1 ›› 2016, Vol. 32 ›› Issue (3): 379-387.DOI: 10.16409/j.cnki.2095-039x.2016.03.014

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Isolation and Identification of the Strain YR-35 Resistant to Phytophthora infestans and Its Metabolites

REN Xingbo, ZHANG Ziliang, ZHAO Puyu, WU Zhihua, CUI Haichen, LIU Huirong   

  1. College of Life Sciences, Inner Mongolia Agricultural University, Hohhot 010018, China
  • Received:2015-09-06 Online:2016-06-08 Published:2016-06-07

Abstract: A strain (YR-35) highly resistant to Phytophthora infestans was isolated from soil samples collected from a farmland of the Ulashan Town and identified as Myxococcus virescens by its morphological, physiological and biochemical characteristics, and its 16S rDNA gene sequence. The strain showed significant resistance against the pathogen of potato late blight, P. infestans, and an inhibition rate of 96.67% on the mycelial growth of this species. The antibiotic substances could tolerate high temperature well. Their activity could be maintained from 30 to 80 ℃ (inhibition rate of 21.70%) and decreased when the temperature exceeded 80 ℃. Their activity still remained an inhibition rate of 15.38% after treated at 90 ℃ for 1 h. The active substances were stable from pH 5.0 to 9.0 and maintained an inhibition rate above 25.27%. Their activity significantly decreased when the pH value was less than 5.0 or greater than 9.0. The active substances could not be degraded by protease and their activity was not affected by UV and natural light exposure. The relative lesion area of potato leaves declined from 87.72% to 0.57% when the sterile fermented supernatant of the strain YR-35 was sprayed on the leaves before the spore suspension of P. infestans was inoculated. The fermented supernatant of the strain YR–35 could effectively inhibit P. infestans from infecting potato leaves. Our study found that M. virescens had significant resistance to P. infestans for the first time, which laid a foundation for the research and development of the biological pesticides for controlling potato late blight effectively.

Key words: Phytophthora infestans, antagonistic strain, isolation and identification, Myxococcus virescens

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