ABSTRACT
Four kinds of colophony were used to isolate the herbicidal substance from the toxin produced by isolate PAM1 of Pythium aphanidermatum, which had herbicidal activity to Digtaria sanguinealis L and the results showed X-5 was the best one for absorbing herbicidal substance among the four kinds of colophony used. Four solvents including 50% ethanol, 95% ethanol, ethyl acetate and acetone were used as eluting solvent and 2 procedures were tested, and the results of growth inhibition and seed germination indicated that the best eluting procedure was procedure 1.
ABSTRACT
Five fractions,Ⅰ(R_f0.06)、Ⅱ(R_f0.21)、Ⅲ(R_f0.45)、Ⅳ(R_f0.60)、Ⅴ(R_f0.75)have been obtained after HT-toxin from race 1 of Exserohilum turcicum 99-2 isolated by TLC. In all of these fractions,only fractions Ⅱ had specific toxicity to the corn leaves with Ht1 gene. Then fractions Ⅱ-1、Ⅱ-2、Ⅱ-3 were isolated from fractions Ⅱ by HPLC purification,and the bioassay result showed only fraction Ⅱ-3 was toxigentic to corn leaves with Ht1 gene but non-toxigentic to corn leaves without Ht1 gene. Fractions Ⅱ-1、Ⅱ-2 and Ⅱ-3 were scanned by UV-Vis spectrophotometer. It was shown that the fractions Ⅱ-1 and Ⅱ-2 had analogous spectrum,and especially the fraction Ⅱ-3 had a special peak at 300nm.
ABSTRACT
Melanin is formed by oxidative polymerization of phenolic compounds,basically different kinds of melanin come from different organisms.DOPA melanin and DHN melanin have same physical and chemical characters although they have different biosynthetic pathway.DHN melanin is common in plant fungi and plays an important role on infection.The melanin accumulates in the fungal cell walls and prevents organic and inorganic molecules penetrating out,that insures appressorium's pressure and infection ability.This paper has reviewed the kinds and characters,especially discussed the role of melanin during pathogen infection based on our some research.