Effect of Exogenous Iron Ion on the Biological Characteristics and Pathogenicity of Verticillium dahliae
In order to investigate the effect of iron ions on the biological characteristics and pathogenicity of Verticillium dahliae in sunflower,the growth rate,conidial production,number of microsclerotia,crude toxin secre-tion,cell wall degrading enzymes activity and pathogenicity of V.dahliae were measured after the exogenous addition of iron ions to the culture medium.The results showed that the growth rate and conidial production of mycelium showed an increasing trend after adding different concentrations of iron ions in an exogenous,compared with the control,the growth rate of V.dahliae was the fastest after adding 80 μmol/L of iron ions,and the colony diameter was 68.81 mm with a growth rate of 21.40%;the conidial production was 2.58×107 conidia/mL with a growth rate of 21.13%;the number of microsclerotia also increased with the increase of exogenously added iron ion con-centration,and after 5 days of culture,its increase was 51.53%compared with the control.The crude toxin secretion was increased after adding 80 μmol/L of iron ions,and the increase rate was nearly doubled.The activity of cell wall lyase increased with increasing concentration of exogenous iron ions and increased at 80 μmol/L reached the strongest.In addition,the pathogenicity of V.dahliae increased accordingly with the increase in the concentration of iron ions in the medium,as shown by the increase in the disease index from 35.00 to 62.20 when the concentration of iron ions added exogenously from0 to 80 μmol/L,with a growth rate of 77.71%.In conclusion,the exogenous addition of iron ions not only accelerates the growth of V.dahliae,and promotes conidial production and microsclero-tia formation,but also enhances the pathogenicity of V.dahliae.
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