Root responses to soil physical conditions; growth dynamics from field to cell
Root responses to soil physical conditions; growth dynamics from field to cell
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DOI：
10.1093/jxb/erj003
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发表时间：
2006-01-01
影响因子：
6.9
通讯作者：
Valentine, TA
中科院分区：
文献类型：
--
作者：
Bengough, AG;Bransby, MF;Valentine, TA
田间根系生长常因土壤物理应力的组合而减慢，包括机械阻抗、水分胁迫和缺氧。工作应力可能会不断变化，这取决于根在土壤剖面中的位置，主要的土壤水分条件，以及土壤被压实的程度。根生长反应的动态被认为是在本文中，连同细胞的反应，它们的基础。某些根的反应促进在硬土中的伸长，例如，边缘细胞的脱落增加，根冠的渗出物减少摩擦;根的增厚减轻根尖前的应力并减少屈曲。整个根系也可能优先生长在松散与致密的土壤中，但这种反应取决于基因型和松散和致密土壤相对于主根轴的空间排列。根伸长的减少往往伴随着细胞通量和轴向细胞延伸的减少，最近基于计算机的模型正在增加我们对这些过程的理解。在机械阻抗的情况下，细胞形状发生大的变化，产生较短较胖的细胞。关于这种反应的许多方面仍然存在不确定性，包括控制轴向和径向延伸的细胞壁的变化，以及表皮、皮层和中柱控制根伸长的程度。光流技术使根表面随时间的跟踪产生二维速度场的估计。它表明，这些技术可以成功地应用于活根的共聚焦显微镜图像的延时序列，以确定速度场和应变率的细胞群。结合新的分子方法，这提供了一个有前途的方式调查和建模的机制控制生长扰动响应环境应力。
Root growth in the field is often slowed by a combination of soil physical stresses, including mechanical impedance, water stress, and oxygen deficiency. The stresses operating may vary continually, depending on the location of the root in the soil profile, the prevailing soil water conditions, and the degree to which the soil has been compacted. The dynamics of root growth responses are considered in this paper, together with the cellular responses that underlie them. Certain root responses facilitate elongation in hard soil, for example, increased sloughing of border cells and exudation from the root cap decreases friction; and thickening of the root relieves stress in front of the root apex and decreases buckling. Whole root systems may also grow preferentially in loose versus dense soil, but this response depends on genotype and the spatial arrangement of loose and compact soil with respect to the main root axes. Decreased root elongation is often accompanied by a decrease in both cell flux and axial cell extension, and recent computer-based models are increasing our understanding of these processes. In the case of mechanical impedance, large changes in cell shape occur, giving rise to shorter fatter cells. There is still uncertainty about many aspects of this response, including the changes in cell walls that control axial versus radial extension, and the degree to which the epidermis, cortex, and stele control root elongation. Optical flow techniques enable tracking of root surfaces with time to yield estimates of two-dimensional velocity fields. It is demonstrated that these techniques can be applied successfully to time-lapse sequences of confocal microscope images of living roots, in order to determine velocity fields and strain rates of groups of cells. In combination with new molecular approaches this provides a promising way of investigating and modelling the mechanisms controlling growth perturbations in response to environmental stresses.