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The reaction of monogenic resistant and susceptible varieties of tomato to inoculation with Fusarium oxysporum f. Zycopersici into stems or through Bonny Best rootstocks
Author(s) -
KEYWORTH W. G.
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.tb03749.x
Subject(s) - rootstock , biology , inoculation , browning , fungus , horticulture , fusarium oxysporum , plant disease resistance , resistance (ecology) , botany , agronomy , biochemistry , gene
SUMMARY The aerial parts of tomato varieties showing low and high (monogenic) resistance to Fusarium wilt were inoculated, either directly into stems or through the roots of low resistance Bonny Best rootstocks on to which they had been grafted. Symptom development was recorded and the distribution of the fungus within the plants was determined by isolation. From stem inoculations the fungus invaded Bonny Best stems and leaves (although much less readily than from root inoculations) and caused mild symptoms. Little or no invasion of Jefferson (high resistance) stems occurred and there were no symptoms. It was concluded that the stems of the two varieties differed in resistance to invasion. When invaded from infected Bonny Best rootstocks, scions of five varieties of low resistance showed normal wilt development with considerable leaf flaccidity. Vascular browning in the leaves was often associated with the presence of the fungus. Scions of six monogenic high‐resistance varieties invaded from Bonny Best rootstocks showed symptoms more quickly and of a different type (severe yellowing and necrosis with less leaf flaccidity). Vascular browning was extensive in the leaves but was produced far in advance of fungal invasion, which was normally restricted to the lower part of the stem. It appeared that the scions were highly sensitive to toxins produced in the lower part of the plant. These differences were apparent when scions of the two types were invaded from a common rootstock. The results confirm the observations of other workers that the stems as well as the roots of monogenic resistant varieties of tomato show greater resistance to invasion by Fusarium than corresponding organs of tomato varieties of low resistance. They also provide an explanation for the apparently conflicting results of previous grafting experiments.