Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Biochemie der Pflanze, Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, Göttingen, Germany.
Planta. 2011 Jan;233(1):139-52. doi: 10.1007/s00425-010-1285-8. Epub 2010 Oct 12.
To understand carbon partitioning in roots and nodules of Datisca glomerata, activities of sucrose-degrading enzymes and sugar transporter expression patterns were analyzed in both organs, and plasmodesmal connections between nodule cortical cells were examined by transmission electron microscopy. The results indicate that in nodules, the contribution of symplastic transport processes is increased in comparison to roots, specifically in infected cells which develop many secondary plasmodesmata. Invertase activities are dramatically reduced in nodules as compared to roots, indicating that here the main enzyme responsible for the cleavage of sucrose is sucrose synthase. A high-affinity, low-specificity monosaccharide transporter whose expression is induced in infected cells prior to the onset of bacterial nitrogen fixation, and which has an unusually low pH optimum and may be involved in turgor control or hexose retrieval during infection thread growth.
为了理解 Datisca glomerata 根和根瘤中的碳分配，分析了这两个器官中蔗糖降解酶的活性和糖转运蛋白的表达模式，并通过透射电子显微镜检查了根瘤皮层细胞之间的胞质连丝连接。结果表明，与根相比，根瘤中胞质运输过程的贡献增加，特别是在发育有许多次生胞质连丝的感染细胞中。与根相比，根瘤中的转化酶活性显著降低，表明蔗糖的主要裂解酶是蔗糖合酶。一种高亲和力、低特异性的单糖转运蛋白，其表达在细菌固氮开始前诱导感染细胞表达，该蛋白具有异常低的 pH 最适值，可能参与感染丝生长过程中的膨压控制或己糖回收。
