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A physiological difference between bean leaves ( Phaseolus vulgaris ), resistant and susceptible to halo blight, caused by Pseudomonas phaseolicola
Author(s) -
DEVERALL B. J.,
WALKER J. C.
Publication year - 1963
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.1963.tb03732.x
Subject(s) - phaseolus , biology , botany , inoculation , oxygen , horticulture , chemistry , organic chemistry
SUMMARY Lines of bean ( Phaseolus vulgaris ), which were resistant or susceptible to the halo‐blight disease incited by Pseudomonas phaseolicola , were derived from a cross between the resistant variety Red Mexican U.I. No. 3 and the susceptible variety Kinghorn Wax. Homogenates of the leaves absorbed oxygen rapidly when placed in an oxygen electrode or a Warburg flask. Preparations of healtlyj resistant leaves had a higher uptake than those of healthy susceptible leaves, grown to the same stage at the same time. This was checked on the parental varieties and with 24 F 3 progenies of the cross. Only one line, a resistant, was difficult to distinguish by oxygen uptake on some occasions. Attempts were made, using the crude homogenates, to reveal the nature of the oxidation as a guide to more precise analysis. Maximum uptake occurred between pH 3–4 and 5, homogenate derived from 0.5 g. fresh weight of leaf absorbing about 100 μl. of oxygen in the 1st hr. at 25° C. R.Q.'S were low, 0·06 to 0·3. Several inhibitors of metal oxidases had no effect, but hydroxylamine, azide and cyanide inhibited by 20, 30 and 40%, respectively, at 10 ‐3 M. Krebs cycle acids and malonic acid had no effect, but glycolic and dihydroxymaleic acids were readily oxidized. Preparations from young resistant leaves oxidized dihydroxymaleic acid more rapidly than did those of young susceptible leaves, and the rate could be greatly influenced by different phenols. The oxygen uptake was not thought to be due to respiration, nor was there any evidence that it was associated with copper oxidases. The tentative suggestion is made that the uptake was caused by an oxidative peroxidation, comparable with indoleacetic acid oxidation.