Abstract:
Objective To explore the potential hosts of Alternaria alternata, the pathogen of jujube shrunken-fruit disease (JSFD) and the sources of primary infection for JSFD.
Method The spore suspension of a gfp-tagged strain of A. alternata CN193, designated as CN193::gfp, were inoculated with and without stab wound to the fruits and/or leaves of Lycopersivon esculentum, Nicotiana tabacum, Malus domestica cv. Red Fuji, Pyrus bretschneideri, Populus tomentosa and Populus canadensis from the surrounding area of jujube plantation. The marginal tissues with healthy and diseased parts were transferred onto potato dextrose agar media with supplement of 10 μg·mL-1 hygromycin B, and the infected tissues and the hyphae isolated from each of the inoculated material were observed under fluorescence microscope.
Result All the inoculated materials with stabbing wound, except for N. tabacum plant, developed diseased symptoms after 7 days of inoculation. The disease rates of all the above materials inoculated with spore suspension were 45.8% of L. esculentum fruits, 79.2% of apple fruits, 75.0% of M. domestica cv. Red Fuji leaves, 56.3% of Pyrus bretschneideri fruits, 52.1% of Pyrus bretschneideri leaves, 66.7% of Populus tomentosa leaves and 54.2% of Populus canadensis leaves. Through non-wounded inoculation only L. esculentum fruits showed the symptoms, and all the other treated materials and the controls did not present any visible disease development. Strong fluorescence could be observed in the infected tissues of L. esculentum fruits, and in the hyphae of isolates from all infected materials, including the fruits of L. esculentum, the fruits and leaves of M. domestica cv. Red Fuji, the fruits and leaves of Pyrus bretschneideri, and the leaves of Populus tomentosa and Populus canadensis.
Conclusion The pathogen of JSFD is able to successfully infect the L. esculentum, M. domestica cv. Red Fuji, Pyrus bretschneideri, Populus tomentosa and Populus canadensis, and it could cause the same symptoms as tomato melasma, apple brown spot, pear black spot, and poplar leaf blight, inferring that L. esculentum, M. domestica cv. Red Fuji, Pyrus bretschneideri, Populus tomentosa and Populus canadensis are the potential hosts of JSFD.