Infection and colonization of peanut pods by Aspergillus parasiticus and the expression of the aflatoxin biosynthetic gene, nor-1, in infection hyphae.
XU, H.X., ANNIS, S., LINZ, J. and TRAIL, F.
Physiological and Molecular Plant Pathology 56:185-196.
2000
บทคัดย่อ
A histological study of the host-pathogen interaction between peanut, Arachis hyphogea, and Aspergillus parasiticus was performed in a system where peanuts remained attached to the plant and were inoculated without wounding. A genetically tagged strain of A. parasiticus, G5, was engineered to harbour the beta-glucuronidase (GUS) reporter gene under control of the nor-1 promoter from the aflatoxin biosynthetic pathway. This strain was used to follow infection and aflatoxin production during colonisation of undamaged, drought stressed peanuts. The fungus colonised all tissues of the peanut pod and appeared to gain ingress through the corky layer of the pericarp. Two morphologically distinct types of hyphae were seen throughout the pod tissues. Statistical analysis revealed that the narrower hyphae were significantly more likely to produce GUS activity than wider ones. GUS activity was found in hyphae infecting the pericarp, embryo and cotyledons indicating expression of aflatoxin biosynthetic genes in these tissues. GUS activity was not observed in the hyphae colonising the testa.