Table_1_Drought-Induced Root Pressure in Sorghum bicolor.xls

Root pressure, also manifested as profusive sap flowing from cut stems, is a phenomenon in some species that has perplexed biologists for much of the last century. It is associated with increased crop production under drought, but its function and regulation remain largely unknown. In this study, we investigated the initiation, mechanisms, and possible adaptive function of root pressure in six genotypes of Sorghum bicolor during a drought experiment in the greenhouse. We observed that root pressure was induced in plants exposed to drought followed by re-watering but possibly inhibited by 100% re-watering in some genotypes. We found that root pressure in drought stressed and re-watered plants was associated with greater ratio of fine: coarse root length and shoot biomass production, indicating a possible role of root allocation in creating root pressure and adaptive benefit of root pressure for shoot biomass production. Using RNA-Seq, we identified gene transcripts that were up- and down-regulated in plants with root pressure expression, focusing on genes for aquaporins, membrane transporters, and ATPases that could regulate inter- and intra-cellular transport of water and ions to generate positive xylem pressure in root tissue.

根压，亦表现为切割茎部后大量树液溢出，是某些物种中困扰生物学家近一个世纪的神秘现象。它与干旱条件下的作物增产有关，但其功能与调控机制仍鲜为人知。在本研究中，我们对高粱（Sorghum bicolor）六个基因型在温室干旱实验中根压的启动、机制及其可能的适应性功能进行了探讨。我们观察到，在干旱后重新灌水的植物中诱导了根压，但在某些基因型中，100%的重新灌水可能抑制了根压的产生。我们发现，在干旱胁迫后重新灌水的植物中，根压与细根与粗根长度的比值以及枝条生物量的产生呈正相关，这表明根的分配可能在产生根压中发挥作用，且根压的适应性可能对枝条生物量的产生有益。通过RNA-Seq技术，我们鉴定了在表达根压的植物中上调和下调的基因转录本，重点关注了可调节细胞内外水分和离子运输的渗透素、膜转运蛋白和ATP酶等基因，这些基因可能调控根组织中木质部产生正压力。