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Effect of open‐air fumigation with sulphur dioxide and ozone on phyllosphere and endophytic fungi of conifer needles
Author(s) -
MAGAN N.,
KIRKWOOD I. A.,
MCLEOD A. R.,
SMITH M. K.
Publication year - 1995
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1995.tb00364.x
Subject(s) - fumigation , ozone , phyllosphere , botany , biology , sulfur dioxide , plant use of endophytic fungi in defense , environmental science , horticulture , chemistry , ecology , bacteria , genetics , organic chemistry
The phyllosphere microbial populations inhabiting the needles of three conifer species, Scots pine ( Pinus sylvestris L.), Sitka spruce ( Picea sitchensis L.) and Norway spruce ( Picea abies (L.) Karst.), exposed to SO 2 and O 3 , in an open‐air fumigation experiment were analysed over a 3 year period using serial dilution after washing, direct plating and a fluorescein diacetate (FDA) enzyme assay. Total fungal populations ranged from 10 2 to 10 5 colonyforming units (CPU) g −1 fresh weight of needles. The dominant fungi isolated from needles varied with tree species and isolation technique; Aureobasidium pullulans (de Bary) Arnaud was most common on Scots pine and Norway spruce and white yeasts on Sitka spruce using the dilution plating method. However, direct plating of needle segments onto culture media indicated that Sclerophoma pythiophila (Corda) Hohnel was dominant on Scots pine and A. pullulans on Sitka and Norway spruce. Green needles of Sitka spruce were found to be endophytically colonized by Rhizosphaera kalkhoffii Bubak, but seldom by Lophodermium piceae (Fuckel) Hohn during extensive sampling in 1990. Statistical analyses revealed significant differences ( P <0.05) between plots in the 3 year mean of the total fungal populations or the fungal biomass (FDA assay) on all three tree species. Differences between plots were also observed for a number of dominant component species. Data were also analysed for treatment effects. A significant effect of SO 2 treatment was observed on the total fungal populations on Sitka spruce ( P <0.05) which were reduced markedly by the low‐SO 2 treatment, while the O 3 treatment caused a significant increase in total fungal numbers on Scots pine ( P <0.05). The FDA activity on needles of both Scots pine and Sitka spruce was noticeably higher in the 0 3 ‐only treatment plot, but the overall O 3 effect was not significant. Treatment effects were also detected on the occurrence of component species. The serial dilution method revealed an SO 2 effect ( P <0.05) of a reduction in the occurrence of pink yeasts on Sitka spruce and an O 3 effect ( P <0.05) of an increase in the occurrence of S. pythiophila on Sitka spruce ( P <0.01) but a decrease of Epicoccum nigrum Link and Cladosporium spp. on Scots pine. The direct‐plating method revealed an SO 2 effect of an increase in S. pythiophila on Norway spruce ( P <0.05). Ozone treatment caused a significant increase in the isolation of a black strain of A. pullulans on Norway spruce ( P <0.05). Endophytic colonization of Sitka spruce needles by R. kalkhoffii was found to be increased on two occasions by O 3 exposure.