Jia W, Zhang J, Liang J
Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong, ROC.
J Exp Bot. 2001 Feb;52(355):295-300.
Water deficit-induced ABA accumulation in relation to cellular water relations was investigated in maize root and leaf tissues. While polyethylene glycol (PEG) treatment led to a significant increase of ABA content in both root and leaf tissues, ethylene glycol (EG), a permeable monomer of PEG, had no effect on ABA accumulation at similar or much lower osmotic potentials. A rapid and massive accumulation of ABA in leaf tissues occurred at a specific threshold of PEG 6000 concentration, about 20% (w/v), and closely coincided with the start of the tissue weight loss and the obvious decrease of cellular osmotic potential. Pretreatment with EG lowered the cell sap osmotic potential and also lowered the capability of both root and leaf tissues to accumulate ABA in response to further air-drying or PEG treatment. When samples were dehydrated and incubated under pressure, a method to maintain high water potential and pressure potential during dehydration, ABA accumulation was similar to those dehydrated and incubated under atmospheric pressure. Such results suggest that both the absolute water potential and pressure potential per se had no direct effects on the dehydration-induced ABA accumulation. The results have provided evidence that the initiation of ABA accumulation is related to the weight loss of tissues or changes in cellular volume rather than the cell water relation parameters, and the capability of ABA accumulation can be regulated by cellular osmotic potential.
研究了水分亏缺诱导的脱落酸（ABA）积累与玉米根和叶组织细胞水分关系之间的联系。虽然聚乙二醇（PEG）处理导致根和叶组织中ABA含量显著增加，但乙二醇（EG），一种PEG的可渗透单体，在相似或更低的渗透势下对ABA积累没有影响。在PEG 6000浓度达到约20%（w/v）的特定阈值时，叶组织中迅速大量积累ABA，且这与组织重量开始减轻以及细胞渗透势明显降低密切相关。用EG预处理降低了细胞液渗透势，也降低了根和叶组织在进一步风干或PEG处理时积累ABA的能力。当样品脱水并在压力下孵育时，这是一种在脱水过程中维持高水势和压力势的方法，ABA积累与在大气压下脱水并孵育的情况相似。这些结果表明，绝对水势和压力势本身对脱水诱导的ABA积累没有直接影响。结果提供了证据，表明ABA积累的起始与组织重量减轻或细胞体积变化有关，而非细胞水分关系参数，并且ABA积累能力可由细胞渗透势调节。
