University of Idaho, Department of Biological Sciences, Box 443051, Moscow, Idaho 83844, USA.
Mycologia. 2011 Mar-Apr;103(2):291-306. doi: 10.3852/10-064. Epub 2010 Sep 19.
How plants and microbes recognize each other and interact to form long-lasting relationships remains one of the central questions in cellular communication. The symbiosis between the filamentous fungus Cladonia grayi and the single-celled green alga Asterochloris sp. was used to determine fungal and algal genes upregulated in vitro in early lichen development. cDNA libraries of upregulated genes were created with suppression subtractive hybridization in the first two stages of lichen development. Quantitative PCR subsequently was used to verify the expression level of 41 and 33 candidate fungal and algal genes respectively. Induced fungal genes showed significant matches to genes putatively encoding proteins involved in self and non-self recognition, lipid metabolism, and negative regulation of glucose repressible genes, as well as to a putative d-arabitol reductase and two dioxygenases. Upregulated algal genes included a chitinase-like protein, an amino acid metabolism protein, a dynein-related protein and a protein arginine methyltransferase. These results also provided the first evidence that extracellular communication without cellular contact can occur between lichen symbionts. Many genes showing slight variation in expression appear to direct the development of the lichen symbiosis. The results of this study highlight future avenues of investigation into the molecular biology of lichen symbiosis.
植物和微生物如何相互识别并形成持久的关系，这仍然是细胞通讯中的核心问题之一。丝状真菌 Cladonia grayi 和单细胞绿藻 Asterococcus sp. 的共生关系被用来确定早期地衣发育过程中体外上调的真菌和藻类基因。在地衣发育的前两个阶段，利用抑制性消减杂交技术构建了上调基因的 cDNA 文库。随后，定量 PCR 分别用于验证 41 个和 33 个候选真菌和藻类基因的表达水平。诱导的真菌基因与假定编码参与自我和非自我识别、脂类代谢以及葡萄糖抑制基因负调控的蛋白质的基因、假定的 d-阿拉伯糖醇还原酶和两种双加氧酶有显著的匹配。上调的藻类基因包括几丁质酶样蛋白、氨基酸代谢蛋白、动力蛋白相关蛋白和精氨酸甲基转移酶。这些结果还首次提供了证据表明，无细胞接触的细胞外通讯可以在地衣共生体之间发生。许多表达略有差异的基因似乎指导着地衣共生体的发育。本研究的结果突出了未来对地衣共生体分子生物学的研究方向。
