PCR test to detect Apiosporina morbosa
A specific and sensitive PCR test was developed in Canada to detect Apiosporina morbosa (EPPO A1 List). A. morbosa is a serious disease of Prunus causing black knots on twigs and branches. It has a long latent period, as knots usually appear 1 year after infection. A. morbosa affects a wide range of wild and cultivated Prunus species. In Ontario, A. morbosa is found on many wild hosts (P. americana, P. virginiana, P. pensylvanica). In the Niagara peninsula, significant production losses have been observed on sour cherry (P. cerasus). Cultivated plums (P. domestica and P. salicina) are also susceptible to the disease in Eastern Canada. In the Prairie Provinces, the disease incidence has recently increased in nurseries and city plantings on the ornamental cultivar P. virginiana ‘Shubert Select’.
A pair of specific primers was designed. Specificity was tested with DNA derived from 64 pure cultures of A. morbosa (including 42 single-spore isolates), 22 isolates of other fungi (including species which are often associated with knots), as well as healthy and diseased plant branches collected from the field. Almost all tested isolates of A. morbosa had been collected from wild P. virginiana and the ornamental P. virginiana cv. ‘Shubert Select’. This PCR assay showed high specificity and sensitivity in detecting A. morbosa.
Sources
Zhang JX, Fernando WGD, Remphrey WR (2005) Molecular detection of Apiosporina morbosa, causal agent of black knot in Prunus virginiana. Plant Disease 89(8), 815-821.