Roman-Reyna Veronica, Rathjen John P
Research School of Biology, Australian National University, Linnaeus Way, Canberra, Australia.
Methods Mol Biol. 2017;1659:125-134. doi: 10.1007/978-1-4939-7249-4_11.
Biotrophic fungi such as rusts modify the nutrient status of their hosts by extracting sugars. Hemibiotrophic and biotrophic fungi obtain nutrients from the cytoplasm of host cells and/or the apoplastic spaces. Uptake of nutrients from the cytoplasm is via intracellular hyphae or more complex structures such as haustoria. Apoplastic nutrients are taken up by intercellular hyphae. Overall the infection creates a sink causing remobilization of nutrients from local and distal tissues. The main mobile sugar in plants is sucrose which is absorbed via plant or fungal transporters once unloaded into the cytoplasm or the apoplast. Infection by fungal pathogens alters the apoplastic sugar contents and stimulates the influx of nutrients towards the site of infection as the host tissue transitions to sink. Quantification of solutes in the apoplast can help to understand the allocation of nutrients during infection. However, separation of apoplastic fluids from whole tissue is not straightforward and leakage from damaged cells can alter the results of the extraction. Here, we describe how variation in cytoplasmic contamination and infiltrated leaf volumes must be controlled when extracting apoplastic fluids from healthy and rust-infected wheat leaves. We show the importance of correcting the data for these parameters to measure sugar concentrations accurately.
活体营养型真菌，如锈菌，通过摄取糖分来改变宿主的营养状况。半活体营养型和活体营养型真菌从宿主细胞的细胞质和/或质外体空间获取营养。从细胞质中摄取营养是通过细胞内菌丝或更复杂的结构，如吸器。质外体营养由细胞间菌丝吸收。总体而言，感染会形成一个库，导致营养物质从局部和远端组织重新分配。植物中主要的可移动糖是蔗糖，一旦卸载到细胞质或质外体中，蔗糖就会通过植物或真菌转运蛋白被吸收。真菌病原体的感染会改变质外体糖含量，并在宿主组织转变为库时刺激营养物质向感染部位流入。对质外体中溶质的定量有助于了解感染过程中营养物质的分配。然而，从整个组织中分离质外体流体并非易事，受损细胞的渗漏会改变提取结果。在这里，我们描述了从健康和感染锈菌的小麦叶片中提取质外体流体时，如何控制细胞质污染和渗透叶体积的变化。我们展示了校正这些参数数据以准确测量糖浓度的重要性。
