温室条件下AM真菌和禾草内生真菌对根腐离蠕孢侵染黑麦草的影响

在温室盆栽条件下,以侵染禾草内生真菌(E+)和未侵染禾草内生真菌(E-)的黑麦草种子为材料,设立接种丛枝菌根(arbuscular mycorrhiza,AM)真菌根内球囊霉(AM)和不接AM真菌的对照(NM)处理,并在上述处理下植物生长6周后,在植物根部(B+根)和叶片(B+叶)接种病原菌根腐离蠕孢,以不接种病原菌(B-)的处理作为对照,病原菌接种2周后,通过测定菌根侵染率、发病率、叶绿素含量、光合指标、P含量、SOD活性以及MDA和H₂O₂浓度的变化,研究AM真菌和禾草内生真菌互作对病原菌侵染后黑麦草生长和生理生化指标的影响。结果表明:叶片接种病原菌的黑麦草发病率为2.50%~31.25%。AM真菌和禾草内生真菌的存在均可在一定程度上降低发病率,促进P吸收和光合作用的进行,增加生物量的积累。与NME-对照相比,侵染禾草内生真菌和接种AM真菌的处理降低了叶部接种病原菌的黑麦草发病率,降幅为32.00%~92.00%。叶片和根部接病原菌的黑麦草,AM真菌和禾草内生真菌共同作用时,植物净光合速率、气孔导度、叶绿素含量、总P含量和SOD酶活性分别提高132.25%和132.17%、56.00%和134.48%、37.69%和40.77%、41.51%和38.17%、95.65%和11.72%(P<0.05),MDA和H₂O₂浓度分别降低31.36%和24.45%以及58.62%和22.22%(P<0.05)。这些研究结果表明,AM真菌和禾草内生真菌能促进植物生长,提高植物抗病性,且二者共存时,效果最好。

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

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.