盐胁迫下平欧杂种榛苗木根系离子流特征及其对离子转运体抑制剂的响应

Ion flux characteristics of root and their response to ion transport inhibitors of Corylus heterophylla×C.avellana seedlings under salt stress

盐胁迫导致平欧杂种榛体内原有的K^(+)/Na^(+)失衡,但活体状态下的根系离子动态转运对盐胁迫的响应机制仍未明晰。以平欧杂种榛‘达维’苗木为材料,在水培条件下经0(对照)和200 mmol·L−1 NaCl处理,利用非损伤微测技术,研究盐胁迫下的根系离子流特征及其对抑制剂的响应。结果表明,分生区Na^(+)流速稳定,流向不变,为离子流的最佳扫描位置。根系离子流对盐胁迫与离子转运体抑制剂的响应具有高度特异性。盐胁迫下,分生区Na^(+)、K^(+)净外排量和H^(+)净内流量均显著增加,分别较对照提高287.8%、134.4%和188.7%。质膜Na^(+)/H^(+)逆向转运蛋白抑制剂阿米洛利和质膜H^(+)-ATP酶抑制剂钒酸钠显著限制了NaCl胁迫引起的Na^(+)外排和H^(+)内流,Na^(+)净外排量和H^(+)净内流量分别降低63.5%和138.1%。NaCl胁迫引起的K^(+)外排受到K^(+)通道抑制剂氯化四乙胺的明显抑制和钒酸钠的显著促进,K^(+)净外排量分别降低68.5%和提高69.0%。综合分析表明,NaCl胁迫通过上调根系质膜Na^(+)/H^(+)逆向转运体系(Na^(+)/H^(+)逆向转运体和H^(+)泵)活性,在促进Na^(+)和H^(+)逆向跨膜转运的同时,抑制去极化激活的K^(+)通道来减缓盐诱导的K^(+)外流。

Salt stress leads to the original K^(+)/Na^(+)imbalance in the Corylus heterophylla×C.avellana,however,the response mechanism of root ion dynamic transport to salt stress remains unclear in the living state.In this study,the C.heterophylla×C.avellana‘Dawei’were selected as testing materials.The seedlings were treated with 0(control)and 200 mmol·L−1 NaCl under hydroponic conditions.Subsequently,the ion flux characteristics and their response to inhibitors of root under salt stress were studied using the non-invasive micro-test technique(NMT).The results showed that the net Na^(+)flux in the meristematic zone was stable and the direction was unchanged,which was the best scanning position for ion flow.There were mainly high ion-specific effects on NaCl and inhibitor-induced ion flux in roots.Under salt stress,the net Na^(+)and K^(+)efflux and H^(+)influx in the meristematic zone were significantly increased,which increased by 287.8%,134.4%and 188.7%compared with the control,respectively.Amiloride,an inhibitor of plasma membrane Na^(+)/H^(+)antiporter,and sodium vanadate,an inhibitor of plasma membrane H^(+)-ATPase,significantly restricted the NaCl-induced Na^(+)efflux and H^(+)influx.The net Na^(+)efflux and H^(+)influx decreased by 63.5%and 138.1%respectively.The NaCl-induced K^(+)efflux was significantly inhibited by the K^(+)channel inhibitor tetraethylammonium chloride,and significantly promoted by sodium vanadate,which decreased by 68.5%and increased by 69.0%,respectively.In conclusion,our data revealed that the NaCl stress upward regulated the plasma membrane Na^(+)/H^(+)antiport system(Na^(+)/H^(+)antiporter and H^(+)pump)activity,which promoted the reverse transmembrane transport of Na^(+)and H^(+),and slowed down the Na-Cl-induced K^(+)loss via restricting depolarization-activated K^(+)channels simultaneously.