Grunze Nina, Willmann Martin, Nehls Uwe
Eberhard-Karls-Universität, Physiologische Ökologie der Pflanzen, Auf der Morgenstelle 1, D-72076 Tübingen, Germany.
New Phytol. 2004 Oct;164(1):147-155. doi: 10.1111/j.1469-8137.2004.01158.x.
• By using degenerate primers, five putative poplar monosaccharide transporter genes were isolated from ectomycorrhizas by RT-PCR. The expression profiles of the three most strongly expressed ones are presented in detail. • Two transporter genes (PttMST1.2 and PttMST2.2) were down-regulated by ectomycorrhiza formation. However, PttMST3.1, which showed 10-times higher expression rates in noninfected roots than any other transporter gene, was up-regulated 12-fold in mycorrhizas. • While changes in PttMST1.2 and PttMST2.2 expression might be regulated by a fungal metabolite present in axenically grown hyphae, the strong increase of PttMST3.1 expression in mycorrhizas required active plant-fungus interaction. • Up-regulation of PttMST3.1 by mycorrhiza formation suggests that root cells are able to compete with fungal hyphae for hexoses from the common apoplast during symbiosis, redirecting the sugar-flux back into plant cells whenever the fungal partner does not supply sufficient mineral nutrients. Such a mechanism would enable the plant to link nutrient supply and fungal carbon support at a local level.
• 通过使用简并引物，利用RT-PCR从外生菌根中分离出5个假定的杨树单糖转运蛋白基因。详细介绍了表达最强的3个基因的表达谱。
• 两个转运蛋白基因（PttMST1.2和PttMST2.2）在外生菌根形成过程中表达下调。然而，PttMST3.1在未感染根中的表达率比其他任何转运蛋白基因高10倍，在菌根中上调了12倍。
• 虽然PttMST1.2和PttMST2.2表达的变化可能受无菌培养菌丝中存在的真菌代谢物调控，但PttMST3.1在菌根中表达的强烈增加需要植物与真菌的积极相互作用。
• 菌根形成对PttMST3.1的上调表明，在共生过程中，根细胞能够与真菌菌丝竞争来自共同质外体的己糖，每当真菌伙伴提供的矿质营养不足时，就将糖流重新导向植物细胞。这种机制将使植物能够在局部水平上连接营养供应和真菌碳支持。
