Heterogeneity in the phloem of minor veins

韧皮部将营养物质、发育信号和防御化合物输送到整个植物体内。通常认为韧皮部是一种同质组织。然而，在初步数据的基础上，研究人员认为，在叶片的小静脉中，运输的材料被装载到韧皮部中，网络在其结构和生物化学上是异质的，具有特定的功能分配给不同的韧皮部细胞亚群。这一假设将通过一些技术在几个物种中进行检验。光学显微镜和电子显微镜将被用来量化参与运输的细胞特异性特征，包括连接韧皮部与周围细胞的通道（胞间连丝）。细胞特异性启动子（控制基因表达的DNA元件）将用于识别静脉内的细胞类型，这些信息将与显微镜结合使用，以分析不同细胞类型中的基因表达模式。在第三个项目中，将用在细胞特异性启动子控制下合成的毒素选择性地杀死特定的韧皮部细胞，这些植物将用于获得和表征韧皮部汁液，以鉴定在单个细胞类型中运输的营养物质、大分子和防御化合物。在更广泛的影响方面，将确定参与合成和运输作物正常发育和健康所需化合物的特定细胞。教育更广泛的影响，包括纳入实验假设和结果在本科课程材料，就业的本科生在韧皮部树液研究，并继续参与康奈尔监狱教育计划。RNA序列数据将存放在国家生物技术信息中心，处理后的数据文件将上传到iPlant。

The phloem transports nutrients, developmental signals and defense compounds throughout the plant body. It is often assumed that the phloem is a homogeneous tissue. However, on the basis of preliminary data the investigators suggest that, in the small veins of leaves where transported materials are loaded into the phloem, the network is heterogeneous in its structure and biochemistry, with specific functions assigned to distinct subsets of phloem cells. This hypothesis will be tested in several species by a number of techniques. Both light and electron microscopy will be used to quantify cell-specific features involved in transport, including the channels (plasmodesmata) that connect the phloem to surrounding cells. Cell-specific promoters (the DNA elements that control gene expression) will be used to identify cell types within veins and this information will be used in conjunction with microscopy to profile gene expression patterns in the different cell types. In a third project, specific phloem cells will be selectively killed with a toxin synthesized under the control of cell-specific promoters and these plants will be used to obtain and characterize phloem sap to identify nutrients, macromolecules and defense compounds transported in individual cell types. In terms of broader impacts, specific cells involved in the synthesis and transport of compounds required for the proper development and health of crop plants will be identified. Educational broader impacts include the incorporation of experimental hypotheses and results in undergraduate course material, employment of undergraduate students in phloem sap studies, and continued participation in the Cornell Prison Education Program. RNA sequence data will be deposited at the National Center for Biotechnology Information and processed data files will be uploaded to iPlant.