链格孢菌毒素细交链孢菌酮酸对空心莲子草的致病性

以空心莲子草离体叶片和植株为材料,采用离体叶片针刺法及离体植株培养法研究链格孢菌毒素细交链孢菌酮酸对空心莲子草的致病性。结果表明,细交链孢菌酮酸对空心莲子草叶片具有较强的致病性。在31.25 ～ 500.00 μg/mL浓度范围内,随着毒素浓度的升高,空心莲子草叶片的病斑直径增大,500.00 μg/mL时为2.41 mm；浓度为20.00 μg/mL时,毒素对空心莲子草植株不同部位叶片的致病性存在差异,对幼嫩的顶部叶片致病性较强；细交链孢菌酮酸对空心莲子草植株的生长产生抑制作用,抑制强度随浓度的升高而增强,与对照相比,当浓度达到125.00 μg/mL时,毒素对植株生长的长度、鲜重及平均根长的抑制作用达到显著水平,浓度达到250.00 μg/mL时,植株的生根数也受到显著抑制,在最高浓度500.00 μg/mL时,植株处于零生长,生长长度和生根数均为0,鲜重为负增长,达－0.77 g。本研究表明细交链孢菌酮酸具有开发为防除空心莲子草生物源除草剂的潜力。

Pathogenicity of tenuazonic acid from Alternaria alternata on Alternanthera philoxeroides

Pathogenicity of tenuazonic acid isolated from Alternaria alternata on Alternanthera philoxeroides was carried out with isolated leaf puncture assay and isolated plant assay. The results suggested that, tenuazonic acid was strongly pathogenic to Alternanthera philoxeroides leaves, increasing spot diameter with the concentration increase from 31.25 to 500.00 μg·mL^-1, the spot diameter was 2.41 mm at 500.00 μg·mL^-1, and it was more pathogenic to the younger leaves in plant tip than the ones in other plant parts at 20.00 μg·mL^-1. Tenuazonic acid inhibited the growth of A. philoxeroides plants, growth length, fresh weight and average root length were significantly inhibited at concentration of 125.00 μg·mL^-1, root number was also significantly inhibited at concentration of 250.00 μg·mL^-1; at 500.00 μg·mL^-1, growth length and root number were both zero, fresh weight decreased 0.77 g. It was concluded that tenuazonic acid had the potential for bioherbicide development for the control of A. philoxeroides．