First report of Diplodia sapinea P. Karst. on Pinus sylvestris L. in Central Siberia
YU. A. LITOVKA1,2,3, S. S. POZNUKHOVA1, N. V. FOMINA1,2, A. A. TIMOFEEV2,3, I. N. PAVLOV1,2
1Reshetnev Siberian State University of Science and Technology, Krasnoyarsk, Russia
2Krasnoyarsk Science Centre of the Siberian Branch of Russian Academy of Science,V. N. Sukachev Institute of Forest of SB RAS, Krasnoyarsk, Russia
3Krasnoyarsk Science Centre of the Siberian Branch of Russian Academy of Science, Krasnoyarsk, Russia
Keywords: phytopathogen, endophyte, Diplodia sapinea, first detection, invasion, temperature stress, enzymatic activity, growth rate
Abstract
For the first time in Central Siberia, in the parks of Krasnoyarsk, on Pinus sylvestris L. trees of different ages with different phytopathological conditions, we identified the invasive species Diplodia sapinea (Fr.) P. Karst., which is a dangerous pathogen of coniferous trees. Pure cultures were isolated from pycnidia on cones; their morphological and molecular genetic characteristics correspond to the species D. sapinea. Siberian isolates are characterized by a high radial growth rate on nutrient media; are phytopathogenic against shoots of P. sylvestris and fruits of Granny Smith apples in vitro. They cause rapid and extensive necrotic lesions of the bark, shoot cambium and fruit pulp; exhibit high peroxidase and protease enzymatic activity. Siberian isolates of D. sapinea do not exceed the parameters of southern isolates in terms of morphological characteristics, enzyme activity and phytopathogenicity. Significant differences are shown with the Dp1-23 strain of Diplodia seriata De Not, isolated from pycnidia on the cones of Cupressus sempervirens L. For Siberian isolates of D. sapinea, high resistance to cold stress was established in the temperature range from -8 to -31 °C in a series of experiments on freezing and thawing of the mycelium. After activation, the radial rowth rate of isolates on PDA at 24 °C turned out to be higher than that of strains that were not subjected to freezing; relatively slow activation was noted at -16 °C compared to other temperatures. The presence of a long endophytic phase in a species first discovered in Central Siberia, high adaptive capabilities and phytopathogenicity pose a particular danger to its spread to a new territory and host plants, which requires special attention and study.
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