Exogenous hydrogen peroxide, nitric oxide and calcium mediate root ion fluxes in two non-secretor mangrove species subjected to NaCl stress
Exogenous hydrogen peroxide, nitric oxide and calcium mediate root ion fluxes in two non-secretor mangrove species subjected to NaCl stress
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外源过氧化氢、一氧化氮和钙介导两种非分泌者红树林物种在 NaCl 胁迫下的根离子通量。
DOI：
10.1093/treephys/tps119
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发表时间：
2013-01-01
期刊：
影响因子：
4
通讯作者：
Chen, Shaoliang
中科院分区：
文献类型：
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作者：
Lu, Yanjun;Li, Niya;Chen, Shaoliang
以木榄（Bruguiera gymnorrhiza（L.）Savigny和秋茄Kandelia candel（L.）Druce，我们比较了两种非分泌型红树林在离子稳态控制方面的物种差异。高盐胁迫（400 mM NaCl，4周）导致根和叶组织中K+/Na+比值下降，其中K的下降更为明显。与B相比，candel（41-66%）。木榄（5-36%）。盐改变流量配置文件的Na+，K+，H+和Ca 2+在根和外源过氧化氢（H2 O2），一氧化氮（NO）和Ca 2+对根离子通量的影响进行了研究，在水培处理短期与100 mM NaCl（ST，24 h）和长期与200 mM NaCl（LT，7天）。短期和LT盐度导致Na+外流和相应增加H+流入两个物种的根，虽然更明显的效果是观察到在B。裸根草Na ~+/H ~+逆向转运蛋白抑制剂阿米洛利和质膜H ~+-ATPase抑制剂原钒酸钠均能明显抑制Na ~+-H ~+交换，表明Na ~+外排是Na ~+主动跨膜的结果。短期和低温盐度对两种植物的K+外流有促进作用，但K. Candel显示出较高的通量率。盐诱导的K ~+外排可被K ~+通道阻断剂氯化四乙基铵明显抑制，表明K ~+外排是由去极化激活的通道，如外向整流钾通道（KORC）和非选择性阳离子通道（NSCC）介导的。外源H2 O2（10 mM）显著增加ST处理根的表观Na+外流和有限的K+外流，但H2 O2在B中引起更高的Na+外流。木榄根CaCl 2（10 mM）抑制了两种红树植物根中K+的流出，但仅在B中发现了CaCl 2对Na+流出的促进作用。裸根草在ST处理下，硝普钠（SNP）（100 µM，NO供体）增加了两个物种根尖的Na+流出;然而，它对K+损失的抑制仅见于K。坎德尔值得注意的是，NaCl引起了B中明显的Ca 2+内流。H2 O2（10 mM）对木榄根生长有促进作用。因此，盐诱导的Ca 2+对B有一定的促进作用。在高盐胁迫下，木榄维持K+/Na+动态平衡的作用。
Using 3-month-old seedlings of Bruguiera gymnorrhiza (L.) Savigny and Kandelia candel (L.) Druce, we compared species differences in ionic homeostasis control between the two non-secretor mangrove species. A high salinity (400 mM NaCl, 4 weeks) resulted in a decline of the K+/Na+ ratio in root and leaf tissues, and the reduction was more pronounced in K. candel (41–66%) as compared with B. gymnorrhiza (5–36%). Salt-altered flux profiles of Na+, K+, H+ and Ca2+ in roots and effects of exogenous hydrogen peroxide (H2O2), nitric oxide (NO) and Ca2+ on root ion fluxes were examined in seedlings that were hydroponically treated short term with 100 mM NaCl (ST, 24 h) and long term with 200 mM NaCl (LT, 7 days). Short term and LT salinity resulted in Na+ efflux and a correspondingly increased H+ influx in roots of both species, although a more pronounced effect was observed in B. gymnorrhiza. The salt-enhanced exchange of Na+ with H+ was obviously inhibited by amiloride (a Na+/H+ antiporter inhibitor) or sodium orthovanadate (a plasma membrane H+-ATPase inhibitor), indicating that the Na+ efflux resulted from active Na+ exclusion across the plasma membrane. Short term and LT salinity accelerated K+ efflux in the two species, but K. candel exhibited a higher flux rate. The salt-induced K+ efflux was markedly restricted by the K+ channel blocker, tetraethylammonium chloride, indicating that the K+ efflux is mediated by depolarization-activated channels, eg, KORCs (outward rectifying K+ channels) and NSCCs (non-selective cation channels). Exogenous H2O2 application (10 mM) markedly increased the apparent Na+ efflux and limited K+ efflux in ST-treated roots, although H2O2 caused a higher Na+ efflux in B. gymnorrhiza roots. CaCl2 (10 mM) reduced the efflux of K+ in salinized roots of the two mangroves, but its enhancement of Na+ efflux was found only in B. gymnorrhiza. Under ST treatment, sodium nitroprusside (SNP)(100 µM, an NO donor) increased Na+ efflux at the root apex of the two species; however, its inhibition of K+ loss was seen only in K. candel. Of note, NaCl caused an obvious influx of Ca2+ in B. gymnorrhiza roots, which was enhanced by H2O2 (10 mM). Therefore, the salt-induced Ca2+ benefits B. gymnorrhiza in maintaining K+/Na+ homeostasis under high external salinity.