拟禾本科根结线虫诱导形成的水稻巨型细胞内蔗糖运输机制研究

Meloidogyne graminicola (MG) is the important soil-borne pathogen of rice, resulted in serious reduction of rice yield. MG obtains nutrients from the feeding sites, giant cells induced by MG itself, such as carbon source. Our previous study showed that sucrose could be transported into MG-induced giant cells in rice through symplasmic unloading. It is different in the transportation of sucrose into M. incognita-induced giant cells in Arabidopsis thaliana. In order to further elucidate the sucrose transport mechanism in MG-induced giant cells in rice, the rice cultivar TN1 will be used as host and the synergistic effect of symplasmic and apoplasmic unloading in the sucrose transportation into giant cells will be investigated through loading experiments of rice leaves with a fluorescent dye. The MG induced rice sugar transporter genes (OsSUTs) in giant cells will also be identified by quantitative real-time PCR. And one mutant of the MG-induced OsSUTs will be developed by CRISPR technology to characterize the potential pivotal role of the interesting OsSUT in the sucrose transportation into giant cells. This study will promote our understanding to sucrose transport mechanisms in feeding sites induced by plant parasitical nematodes, and lay a theoretical foundation for exploring new prevention and control approaches of MG.

拟禾本科根结线虫Meloidogyne graminicola（MG）是为害水稻的重要土传病原，可导致水稻严重减产。MG 诱导形成的水稻根部取食位点巨型细胞为MG 提供碳源等营养物质。我们前期研究发现，MG 诱导形成的水稻巨型细胞中蔗糖可通过共质体途径向胞内运输，这不同于南方根结线虫诱导形成的拟南芥巨型细胞内蔗糖的运输机制。为进一步解析水稻中MG 诱导形成的巨型细胞内蔗糖运输机制，项目以水稻品种TN1 为寄主，通过水稻叶片荧光染料加载试验分析共质体途径和质外体途径在巨型细胞内蔗糖运输中的协同作用。以定量RT-PCR 技术分析巨型细胞中受MG 诱导表达的蔗糖转运蛋白编码基因OsSUTs 的表达，以CRISPR 技术构建其中 1 个OsSUT 的突变体，分析目标OsSUT 在巨型细胞内蔗糖运输中的功能。项目将促进对植物寄生线虫取食位点内蔗糖运输机制的认识，为开发MG 防控新技术提供理论基础。

拟禾本科根结线虫Meloidogyne graminicola（MG）是为害水稻的重要土传病原，可导致水稻严重减产。MG 诱导形成的水稻根部取食位点巨型细胞为MG 提供碳源等营养物质。我们前期研究发现，MG 诱导形成的水稻巨型细胞中蔗糖可通过共质体途径向胞内运输，这不同于南方根结线虫诱导形成的拟南芥巨型细胞内蔗糖的运输机制。为进一步解析水稻中MG 诱导形成的巨型细胞内蔗糖运输机制，项目以水稻品种日本晴为寄主，通过水稻叶片荧光染料加载试验，定量RT-PCR 技术，以及目标基因Promoter::GUS 水稻遗传材料GUS 染色，分析共质体途径和质外体途径在巨型细胞内蔗糖运输中的协同作用。研究结果显示，MG 诱导形成的巨型细胞与邻近细胞间存在共质体连接，蔗糖可通过胞间连丝介导的共质体途径向巨型细胞内运输。而在巨型细胞中，介导蔗糖主动运输的OsSUT1-5 这5个基因未受MG 诱导表达。这表明在MG 诱导形成的水稻根部巨型细胞中，OsSUTs 介导的蔗糖主动运输途径未参与蔗糖的胞内运输。同时，依据CFDA 加载试验结果发现，MG 可操控水稻中蔗糖纵向运输中的共质体运输途径。项目研究结果，增进了对根结线虫诱导形成的巨型细胞内糖类供应机制的认识，以及对巨型细胞与邻近细胞间的组织结构关系的认识，为进一步探究巨型细胞的形态建成和维持机制奠定了基础，为病原物如何操控植物寄主的物质运输，摄取营养物质提供了新的潜在机制。