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Quantification of Infection by Alternaria cassiae Using Leaf Immuno‐Autoradiography and Radioimmunosorbent Assays
Author(s) -
Sharon Amir,
Amsellem Ziva,
Gressel Jonathan
Publication year - 1993
Publication title -
journal of phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 60
eISSN - 1439-0434
pISSN - 0931-1785
DOI - 10.1111/j.1439-0434.1993.tb01381.x
Subject(s) - mycelium , antiserum , biology , alternaria , inoculation , fungus , spore , microbiology and biotechnology , horticulture , botany , antibody , immunology
The severity of fungal infection is usually estimated visually as a rating of injury. A more quantitative method was needed to ascertain the effect of additives used to enhance the virulence of mycoherbicidal preparations. A sensitive and accurate serological method is presented for quantitative measurement of Alternaria cassiae infection of Cassia obtusifolia . An antiserum was prepared against a homogenate of mycelium of A. cassiae . A fast and simple procedure of leaf immuno‐autoradiography was developed for the visualization of A. cassiae mycelium on inoculated leaves. A radioimmunosorbent assay (RISA) was developed for quantification of the extent of fungal infection. As little as 1. 6 ng/ ml dry weight equivalent of mycelium could be detected by RISA. There was a linear relationship between the logarithm of the RISA values and the logarithm of fungus concentration up to 300 ng/ml. Reduced sensitivity of the assay was pronounced in extracts containing 400 μ g/ml or more fresh weight of leaves. There was 30–40 % cross‐reactivity of the antiserum with two other species of Alternaria, as well as with Monilinia fructicola , and almost no reactivity was found with three other fungi tested.