Antimicrobial Activity of Brassinosteroid to Pyricularia oryzae

WANG Mengjiao

doi:10.15933/j.cnki.1004-3268.2017.12.013

Abstract：To inhibit the infection of rice by Pyricularia oryzae effectively,the antimicrobial activity of five plant growth regulators (brassinosteroid,auxin,cytokinin,gibberellin and abscisic acid) was determined by growth rate method using two strains of Pyricularia oryzae(37631,37661),and the effect of brassinosteroid on hypha dry weight and spore germination was studied.The results showed that epi-brassinolide (epi-BL) had a significant inhibitory effect on mycelial elongation of Pyricularia oryzae.When the concentration of epi-BL reached 5 μmol/L,the inhibitory rates on mycelial elongation of two strains were 58.18％ and 53.37％,and the EC50 values were 3.7 μmol/L and 5.2 μmol/L,respectively.At the same time,the colon morphology of two strains was found to be changed after epi-BL treatment.The mycelial elongation of two strains was not significantly inhibited by other four plant growth regulators.The result of hypha dry weight experiment showed that,compared with the control(0 μmol/L epi-BL),the dry weights of two strains were reduced by 52.60％ and 48.44％,respectively,after 8 days of 2 μmol/L epi-BL treatment.epi-BL also had significant inhibitory effect on the spore germination of Pyricularia oryzae.When the concentration reached 5 μmol/L,the inhibition rates on the two strains were 53.25％ and 49.34-％,and the EC5o values were 4.31 μmol/L and 6.42 μmol/L,respectively.Overall,it can be found that the mycelium elongation,dry weight and spore germination of Pyricularia oryzae are significantly influenced by brassinosteroid.