Abstract
In the previous paper (Part 1), it was revealed that the inhibitory effect of basic copper sulfate on the growth of Diaporthe citri depends on Cu2+ ion concentrations but not on basic copper sulfate concentrations. In order to further clarify the correlation between Cu2+ ion absorption and its inhibitory effect, we observed the amount of Cu2+ ion absorption in each organ of D. citri with an electronprobe X-ray microanalyzer. Germination-inhibited pycnospores contained about 1.6 times as much copper as germinating ones. Penetration-inhibited hyphae contained about 4.3 times as much copper as penetrating hyphae. Thus, a positive correlation between Cu2+ ion absorption in each organ of D. citri and its inhibitory effect on pycnospore germination and hyphal penetration was found. Furthermore, germination-inhibited pycnospores contained more copper than penetration-inhibited hyphae, which coincides with the previous observation that inorganic copper inhibits hyphal penetration of D. citri (50% inhibition at pH 6; Cu2+=1.2×10-5M) at lower concentrations than it does pycnospore germination (50% inhibition at pH 6; Cu2+=4.2×10-5M).
