NaCl 对玉米根细胞水力传导度的渗透效应。

Osmotic effects of NaCl on cell hydraulic conductivity of corn roots.

机构信息

Institute of New Forest Technology, Chinese Academy of Forestry, Beijing 100091, China.

出版信息

Acta Biochim Biophys Sin (Shanghai). 2010 May 15;42(5):351-7. doi: 10.1093/abbs/gmq029.

PMID:20458449

Abstract

In this study, whether the effect of salt (NaCl) stress on cell hydraulic conductivity (L(p)) is via osmotic pressure or ion toxicity and whether abscisic acid (ABA) can release the salt adverse effect were tested. Immediate effects of NaCl and ABA on root cortical cell L(p) of maize (Zea mays L.) were detected by measuring changes in half time of water exchange (T(1/2)) and turgor of individual single cells with a cell pressure probe for at least 1 h. The results showed that stepwise additions of NaCl (50 mM) significantly (P < 0.01) reduced the water permeability. One-step addition of 50 mM NaCl even more drastically decreased L(p). ABA was not able to instantaneously reverse the low water permeability induced by the salt stress. Long-term effects of NaCl, mannitol and sorbitol, and ABA on L(p) were measured for 6 days. Both NaCl and a mixture of mannitol and sorbitol, with the same osmotic strength of 0.25 MPa, significantly reduced L(p) at the early stage of the treatments. The declined L(p) in the salinized cell gradually and partially recovered after 2 days, whereas the L(p) with the mannitol and sorbitol mixture treatment was all time inhibited. With long-time treatment, ABA (500 nM) significantly (P < 0.01) increased turgor and L(p) of the NaCl-treated cells. In general, NaCl reduced water permeability of corn root cortical cells most likely by an osmotic stress. ABA could not instantaneously change water permeability of the corn root cortical cell subjected to NaCl stress; however, with long-time treatment, ABA was able to in part relieve the salt stress likely by osmotic adjustment.

摘要

在这项研究中，我们测试了盐（NaCl）胁迫对细胞水力传导性（L(p)）的影响是通过渗透压还是离子毒性，以及脱落酸（ABA）是否可以缓解盐的不利影响。通过测量玉米（Zea mays L.）根皮层细胞半时间水交换（T(1/2)）和单个细胞膨压的变化，用细胞压力探针至少 1 小时检测 NaCl 和 ABA 对根皮层细胞 L(p)的即时影响。结果表明，逐步添加 NaCl（50 mM）显著（P < 0.01）降低了水通透性。一步添加 50 mM NaCl 甚至更剧烈地降低了 L(p)。ABA 不能立即逆转盐胁迫引起的低水通透性。测量了 NaCl、甘露醇和山梨醇以及 ABA 对 L(p)的长期影响，持续 6 天。NaCl 和甘露醇和山梨醇的混合物，渗透压强度相同为 0.25 MPa，在处理的早期阶段显著降低了 L(p)。盐处理细胞中下降的 L(p)在 2 天后逐渐部分恢复，而甘露醇和山梨醇混合物处理的 L(p)则一直受到抑制。经过长时间处理，ABA（500 nM）显著（P < 0.01）增加了 NaCl 处理细胞的膨压和 L(p)。总体而言，NaCl 降低玉米根皮层细胞水通透性的主要原因是渗透压胁迫。ABA 不能立即改变 NaCl 胁迫下玉米根皮层细胞的水通透性；然而，经过长时间处理，ABA 可能通过渗透调节部分缓解盐胁迫。