Transpiration- and growth-induced water potentials in maize.
Transpiration- and growth-induced water potentials in maize.
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玉米蒸腾和生长诱导的水势。
DOI：
10.1104/pp.74.4.882
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发表时间：
1984
期刊：
影响因子：
7.4
通讯作者：
John S. Boyer
中科院分区：
文献类型：
--
作者：
M. Westgate;John S. Boyer
最近的证据表明，叶和茎的水分运动所需的水势梯度（psi（w））比以前假设的要大。由于生长对组织psi（w）敏感，并且这些梯度的行为在蒸腾植物中尚未研究，因此我们研究了玉米（Zea mays L.）在高和低的蒸腾速率下。在植物成熟区测得的psi（w）主要响应蒸腾，而在生长区的psi（w）的蒸腾和生长的影响。成熟组织的蒸腾诱导电位沿蒸腾流形成一个沿着减小的psi（w）梯度，而生长诱导电位从蒸腾流到生长组织中的扩展细胞形成一个减小的psi（w）梯度。当木质部psi（w）在白天下降时，叶内psi（w）的生长诱导梯度保持相当恒定，并且与生长区域的渗透势（psi（s））降低（渗透调节）相关。以psi（w）为单位的生长诱导梯度不是由组织切除引起的，因为完整的玉米茎表现出类似的psi（w）。这些观察结果支持了这样的概念，即需要psi（w）的大梯度来维持所有营养组织内的水流向扩展细胞，并表明维持psi（w）的有利梯度对细胞扩展可能是渗透调节的重要作用。
Recent evidence from leaves and stems indicates that gradients in water potential (psi(w)) necessary for water movement through growing tissues are larger than previously assumed. Because growth is sensitive to tissue psi(w) and the behavior of these gradients has not been investigated in transpiring plants, we examined the water status of all the growing and mature vegetative tissues of maize (Zea mays L.) during high and low rates of transpiration. The psi(w) measured in the mature regions of the plant responded primarily to transpiration, while the psi(w) in the growing regions was affected both by transpiration and growth. The transpiration-induced potentials of the mature tissue formed a gradient of decreasing psi(w) along the transpiration stream while the growth-induced potentials formed a gradient of decreasing psi(w) from the transpiration stream to the expanding cells in the growing tissue. The growth-induced gradient in psi(w) within the leaf remained fairly constant as the xylem psi(w) decreased during the day and was associated with a decreased osmotic potential (psi(s)) of the growing region (osmotic adjustment). The growth-induced gradient in psi(w) was not caused by excision of the tissue because intact maize stems exhibited a similar psi(w). These observations support the concept that large gradients in psi(w) are required to maintain water flow to expanding cells within all the vegetative tissues and suggest that the maintenance of a favorable gradient in psi(w) for cell enlargement may be an important role for osmotic adjustment.