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Inheritance of virulence in Fusarium circinatum , the cause of pitch canker in pines
Author(s) -
Slinski S. L.,
Kirkpatrick S. C.,
Gordon T. R.
Publication year - 2016
Publication title -
plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.928
H-Index - 85
eISSN - 1365-3059
pISSN - 0032-0862
DOI - 10.1111/ppa.12511
Subject(s) - virulence , biology , canker , heritability , genetics , lesion , selection (genetic algorithm) , botany , gene , psychology , artificial intelligence , psychiatry , computer science
Wildtype strains of Fusarium circinatum , the causal agent of pitch canker, were crossed to obtain an F 1 generation. Progeny of this cross were tested for virulence by inoculating Pinus radiata seedlings, and were found to induce a wide range of lesion lengths. Two strains from the F 1 generation that induced long lesions (= high virulence) were used as parents to produce an F 2 generation, followed by a second round of selection for high virulence to obtain an F 3 generation. Mean lesion lengths were not significantly different between the three generations ( P ≥ 0.196). A parallel set of crosses was performed to select for low virulence by using progeny in the F 1 and F 2 generations that induced short lesions as parents for F 2 and F 3 generations, respectively. In this case, both rounds of selection resulted in a significant reduction in mean lesion length, from 33.8 ± 0.8 mm in the F 1 generation, to 19.7 ± 0.7 and 12.9 ± 0.7 mm in the F 2 and F 3 generations, respectively. Thus it is apparent that F. circinatum retains the genetic capacity for avirulence to pines, which could reflect a lack of strong selection for virulence in nature. Progeny of a cross between high and low virulence parents manifested nearly continuous variation in lesion lengths, consistent with virulence being a quantitatively inherited trait. Based on this cross, broad‐sense heritability ( H 2 ) was determined to be 0.74, which suggests that virulence is under strong genetic control.