Department of Plant Science, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada.
Department of Biology, Memorial University of Newfoundland, St. John's, NL, A1C 5S7, Canada.
Planta. 2023 Sep 27;258(5):89. doi: 10.1007/s00425-023-04246-5.
The preservation of quiescent center stem cell integrity in hypoxic roots by phytoglobins is exercised through their ability to scavenge nitric oxide and attenuate its effects on auxin transport and cell degradation. Under low oxygen stress, the retention or induction of phytoglobin expression maintains cell viability while loss or lack of induction of phytoglobin leads to cell degradation. Plants have evolved unique attributes to ensure survival in the environment in which they must exist. Common among the attributes is the ability to maintain stem cells in a quiescent (or low proliferation) state in unfriendly environments. From the seed embryo to meristematic regions of the plant, quiescent stem cells exist to regenerate the organism when environmental conditions are suitable to allow plant survival. Frequently, plants dispose of mature cells or organs in the process of acclimating to the stresses to ensure survival of meristems, the stem cells of which are capable of regenerating cells and organs that have been sacrificed, a feature not generally available to mammals. Most of the research on plant stress responses has dealt with how mature cells respond because of the difficulty of specifically examining plant meristem responses to stress. This raises the question as to whether quiescent stem cells behave in a similar fashion to mature cells in their response to stress and what factors within these critical cells determine whether they survive or degrade when exposed to environmental stress. This review attempts to examine this question with respect to the quiescent center (QC) stem cells of the root apical meristem. Emphasis is put on how varying levels of nitric oxide, influenced by the expression of phytoglobins, affect QC response to hypoxic stress.
植物血球素通过清除一氧化氮并减弱其对生长素运输和细胞降解的影响，从而维持休眠中心干细胞在缺氧根中的完整性。在低氧胁迫下，保留或诱导植物血球素的表达可以维持细胞活力，而丧失或缺乏诱导植物血球素的表达则会导致细胞降解。植物已经进化出独特的属性来确保在其必须生存的环境中生存。这些属性中常见的是能够在不友好的环境中将干细胞维持在休眠（或低增殖）状态。从种子胚胎到植物的分生组织区域，休眠干细胞的存在是为了在环境条件适合植物生存时，使生物体得以再生。植物经常在适应压力的过程中处理成熟细胞或器官，以确保分生组织的生存，这些干细胞能够再生已经牺牲的细胞和器官，这是哺乳动物通常不具备的特征。大多数关于植物应激反应的研究都集中在成熟细胞的反应上，因为专门研究植物分生组织对压力的反应具有一定难度。这就提出了一个问题，即休眠干细胞在应对压力时是否与成熟细胞表现出相似的行为，以及在这些关键细胞中，哪些因素决定了它们在暴露于环境压力时是存活还是降解。本综述试图针对根尖分生组织的休眠中心（QC）干细胞来探讨这个问题。重点介绍了一氧化氮水平的变化如何受植物血球素表达的影响，从而影响 QC 对缺氧胁迫的反应。
