Université Laval, Faculté de Foresterie, de Géographie et de Géomatique, Pavillon Abitibi-Price, 2405 Rue de la Terrasse, Québec, QC G1V 0A6, Canada.
Appl Environ Microbiol. 2010 Apr;76(8):2607-14. doi: 10.1128/AEM.02807-09. Epub 2010 Feb 19.
The impact of transgenic white spruce [Picea glauca (Moench) Voss] containing the endochitinase gene (ech42) on soil fungal biomass and on the ectendomycorrhizal fungi Wilcoxina spp. was tested using a greenhouse trial. The measured level of endochitinase in roots of transgenic white spruce was up to 10 times higher than that in roots of nontransformed white spruce. The level of endochitinase in root exudates of three of four ech42-transformed lines was significantly greater than that in controls. Analysis soil ergosterol showed that the amount of fungal biomass in soil samples from control white spruce was slightly larger than that in soil samples from ech42-transformed white spruce. Nevertheless, the difference was not statistically significant. The rates of mycorrhizal colonization of transformed lines and controls were similar. Sequencing the internal transcribed spacer rRNA region revealed that the root tips were colonized by the ectendomycorrhizal fungi Wilcoxina spp. and the dark septate endophyte Phialocephala fortinii. Colonization of root tips by Wilcoxina spp. was monitored by real-time PCR to quantify the fungus present during the development of ectendomycorrhizal symbiosis in ech42-transformed and control lines. The numbers of Wilcoxina molecules in the transformed lines and the controls were not significantly different (P > 0.05, as determined by analysis of covariance), indicating that in spite of higher levels of endochitinase expression, mycorrhization was not inhibited. Our results indicate that the higher levels of chitinolytic activity in root exudates and root tissues from ech42-transformed lines did not alter the soil fungal biomass or the development of ectendomycorrhizal symbiosis involving Wilcoxina spp.
利用温室试验测试了含有内切几丁质酶基因（ech42）的转基因白云杉[Picea glauca （Moench） Voss]对土壤真菌生物量和外生菌根真菌 Wilcoxina spp. 的影响。转基因白云杉根系中内切几丁质酶的测量水平比非转基因白云杉根系中的内切几丁质酶水平高 10 倍。ech42 转化的 4 个系中的 3 个系的根分泌物中内切几丁质酶的水平明显高于对照。土壤麦角固醇分析表明，对照白云杉土壤样本中的真菌生物量略大于 ech42 转化的白云杉土壤样本中的真菌生物量。然而，这种差异没有统计学意义。转化系和对照系的外生菌根定殖率相似。rRNA 区内部转录间隔区测序显示，ectendomycorrhizal 真菌 Wilcoxina spp. 和暗隔内生真菌 Phialocephala fortinii 定植在根尖。通过实时 PCR 监测 Wilcoxina spp. 对根尖的定植，以量化在 ech42 转化和对照系中 ectendomycorrhizal 共生发育过程中存在的真菌。转化系和对照系中的 Wilcoxina 分子数量没有显著差异（P > 0.05，协方差分析确定），表明尽管内切几丁质酶表达水平较高，但菌根化并未受到抑制。我们的结果表明，ech42 转化系根系分泌物和根系组织中更高水平的几丁质分解活性并未改变土壤真菌生物量或涉及 Wilcoxina spp. 的外生菌根共生的发育。
