Main conclusion Adaptation of the xylem under dehydration to smaller sized vessels and the increase in xylem density per stem area facilitate water transport during water-limiting conditions, and this has implications for assimilate transport during drought. Abstract The potato stem is the communication and transport channel between the assimilate-exporting source leaves and the terminal sink tissues of the plant. During environmental stress conditions like water scarcity, which adversely affect the performance (canopy growth and tuber yield) of the potato plant, the response of stem tissues is essential, however, still understudied. In this study, we investigated the response of the stem tissues of cultivated potato grown in the greenhouse to dehydration using a multidisciplinary approach including physiological, biochemical, morphological, microscopic, and magnetic resonance imaging techniques. We observed the most significant effects of water limitation in the lower stem regions of plants. The light microscopy analysis of the potato stem sections revealed that plants exposed to this particular dehydration stress have higher total xylem density per unit area than control plants. This increase in the total xylem density was accompanied by an increase in the number of narrow-diameter xylem vessels and a decrease in the number of large-diameter xylem vessels. Our MRI approach revealed a diurnal rhythm of xylem flux between day and night, with a reduction in xylem flux that is linked to dehydration sensitivity. We also observed that sink strength was the main driver of assimilate transport through the stem in our data set. These findings may present potential breeding targets for drought tolerance in potato.

中文翻译：

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马铃薯茎秆转运组织对脱水胁迫的形态和生理反应

主要结论 脱水条件下木质部对较小尺寸容器的适应和每茎面积木质部密度的增加促进了限水条件下的水分运输，这对干旱期间的同化运输有影响。摘要 马铃薯茎秆是植物同化输出源叶与末端库组织之间的通讯和运输通道。在诸如缺水等环境胁迫条件下，这会对马铃薯植物的性能（冠层生长和块茎产量）产生不利影响，但茎组织的反应是必不可少的，但仍未得到充分研究。在这项研究中，我们使用包括生理、生化、形态学、显微成像和磁共振成像技术。我们观察到植物下部茎区水分限制的最显着影响。马铃薯茎切片的光学显微镜分析表明，暴露于这种特殊脱水胁迫的植物单位面积的总木质部密度高于对照植物。总木质部密度的增加伴随着小直径木质部血管数量的增加和大直径木质部血管数量的减少。我们的 MRI 方法揭示了白天和黑夜之间木质部通量的昼夜节律，木质部通量减少与脱水敏感性有关。我们还观察到，在我们的数据集中，汇强度是通过茎的同化运输的主要驱动力。