Heterogeneity in Water Availability Alters Cellular Development and Hydraulic Conductivity along Roots of a Desert Succulent
Heterogeneity in Water Availability Alters Cellular Development and Hydraulic Conductivity along Roots of a Desert Succulent
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DOI：
10.1006/anbo.1999.1026
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发表时间：
2000-02
期刊：
影响因子：
4.2
通讯作者：
G. North;P. S. Nobel
中科院分区：
文献类型：
--
作者：
G. North;P. S. Nobel
植物的沙漠肉质龙舌兰deserti种植在分区容器，以确定是否在土壤水分的异质性导致细胞发育和水力传导性的差异，沿着个别根。根从容器与干燥的远侧室（最远的拍摄），潮湿的中间室，和干燥的近侧室的远侧区域（包括根尖），更多的栓化和ligerized内皮层和相邻的细胞层比根区域从潮湿的中间室。近端根区域约40毫米的肉质茎基地也相对unsuberized，这表明外部和内部的水供应延迟组织成熟。根段从潮湿的中间室和干燥的近端室有较高的导水率比更木栓化的根段从干燥的远端室。与湿室的远端根段不同，干室的段浸入氯化汞后，导水率没有下降，这表明水通道蛋白的活性在干旱期间根减少。可能关闭的水道可能有助于限制根系水分流失到干燥的土壤中。栓化细胞层的延迟发育可能允许根区最大限度地从潮湿的土壤斑块（如岩石下）中吸收水分，而相对不成熟的吸收性根区靠近茎基部可能有助于A。沙漠从短暂湿润的表层土壤中吸收水分。
Plants of the desert succulent Agave deserti were grown in partitioned containers to determine whether heterogeneity in soil moisture leads to differences in cellular development and hydraulic conductivity along individual roots. Roots from containers with a dry distal compartment (furthest from the shoot), a wet middle compartment, and a dry proximal compartment had distal regions (including the root tips) that were more suberized and lignified in the endodermis and adjacent cell layers than were root regions from the wet middle compartment. Proximal root regions about 40 mm from the succulent shoot base were also relatively unsuberized, suggesting that both external and internal supplies of water delayed tissue maturation. Root segments from wet middle compartments and from dry proximal compartments had higher hydraulic conductivity than did the more suberized root segments from dry distal compartments. Unlike distal root segments from wet compartments, segments from dry compartments suffered no decrease in hydraulic conductivity after immersion in mercuric chloride, suggesting that aquaporin activity diminished for roots during drought. The possible closure of water channels could help limit root water loss to a drying soil. The delayed development of suberized cell layers may allow root regions to maximize water uptake from wet soil patches (such as under rocks), and the relatively immature, absorptive root region near the base of the shoot may help A. deserti capture water from a briefly wetted surface soil.