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Genetic resistance and tumour morphology in birch infected with Taphrina betulina
Author(s) -
Christita Margaretta,
Overmyer Kirk
Publication year - 2021
Publication title -
forest pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.535
H-Index - 49
eISSN - 1439-0329
pISSN - 1437-4781
DOI - 10.1111/efp.12709
Subject(s) - biology , broom , phloem , botany , xylem , resistance (ecology) , phytoplasma , plant disease resistance , horticulture , genotype , agronomy , ecology , genetics , gene , restriction fragment length polymorphism
Witches’ broom of birch ( Betula spp.) caused by Taphrina betulina is an understudied disease that causes the formation of woody tumours, from which ectopic axillary buds and branches grow to form a broom‐like structure. We have addressed two aspects of this disease using naturally infected mature trees in the field. Broom symptoms offer a convenient means of scoring susceptibility in the field. Variation in broom symptom presentation suggests possible variation in resistance against witches’ broom disease. We tracked the local distribution of susceptible individuals among 721 trees at 159 independent sites. The analysis supports the hypothesis that there was genetic resistance segregating in these birch populations. Anatomical changes in broom symptom bearing branches of European silver birch ( Betula pendula ) were also addressed by comparing sections of tissues from three locations in the same branch, which were normal, swollen in infected tissue adjacent to a tumour, and inside a tumour. Examination of tumours revealed disorganized and swollen xylem, expanded secondary phloem and expanded periderm. Swollen tissues newly infected from spreading disease adjacent to tumours exhibited enhanced growth only in secondary phloem and the periderm, which also exhibited distortions. This finding suggests that tumour formation and possibly pathogen colonization may initiate in these tissues.