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Acta Prataculturae Sinica ›› 2019, Vol. 28 ›› Issue (12): 103-113.DOI: 10.11686/cyxb2019104

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Effects of AM fungus and grass endophyte on the infection of Lolium perenne by the pathogen Bipolaris sorokinianum in a greenhouse

DENG Jie, LI Fang, DUAN Ting-yu*   

  1. State Key Laboratory of Grassland Agro-ecosystem, Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Engineering Research Center of Grassland Industry, Ministry of Education, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China
  • Received:2019-02-23 Online:2019-12-20 Published:2019-12-20

Abstract: In a greenhouse, perennial ryegrass seeds infected with (E+) and without (E-) grass endophyte and pot culture inoculated with (AM) or without (NM) the arbuscular mycorrhizal fungus Rhizophagus intraradices were used as the grass endophyte and AM treatments. The pathogen Bipolaris sorokiniana was inoculated six weeks after seedling emergence by spraying onto leaves and pouring onto soil for root infection, and the same amount of distilled water was applied to non-inoculated (B-) treatments. Two weeks after pathogen inoculation, disease incidence, AM colonization, chlorophyll content, photosynthetic indexes and P content, superoxide dismutase (SOD) activity and malondialdehyde (MDA) and H2O2 concentration of the perennial ryegrass host plants were measured to determine the growth, physiological and biochemical impacts of the pathogen on perennial ryegrass. It was found that the disease incidence of perennial ryegrass inoculated with pathogen ranged from 2.50%-31.25% in leaves. Both AM fungus and grass endophyte reduced the disease incidence, and also promoted P absorption and photosynthesis, and increased the biomass accumulation to some degree. Compared with control treatments, infected with grass endophyte and inoculated with AM fungus decreased disease incidence of perennial ryegrass that inoculated with pathogen in leaves by 32.00%-92.00%. In the all treatments with plants that were infected by pathogen in leaves and roots; the co-colonization of AM fungus and grass endophyte increased net photosynthetic rate, stomatal conductance, chlorophyll content, total P content and SOD enzyme activity by 132.25% and 132.17%, 56.00% and 134.48%, 37.69% and 40.77%, 41.51% and 38.17%, 95.65% and 11.72% (P<0.05), as well as decreased MDA and H2O2 concentration by 31.36% and 24.45%, 58.62% and 22.22%, respectively. These results showed that AM fungi and grass endophyte can promote plant growth and improve plant resistance to disease, and the combination of both the symbiont microorganisms provided the greatest benefit.

Key words: perennial ryegrass, grass endophyte, Rhizophagus intraradices, Bipolaris sorokinianum