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干旱胁迫对油松和柴松钾钙离子流的影响
王树源¹, 王富¹, 唐佳琪，¹
西北农林科技大学林学院

摘要:

【目的】比较干旱胁迫下，油松与柴松幼苗根、叶对K⁺、Ca²⁺的积累规律及其根尖表皮细胞对K⁺、Ca²⁺的跨膜转运模式，从K⁺、Ca²⁺平衡的角度揭示2种松树幼苗对干旱胁迫的响应差异。【方法】以培育5个月的油松和柴松幼苗为试验材料，对其分别进行短期（连续7 d不浇水）和长期（连续21 d不浇水）干旱胁迫处理，以每周浇2次水的幼苗为对照，于干旱胁迫结束时采用原子吸收法测定2种松树根、叶中K⁺、Ca²⁺含量，采用非损伤微测技术检测根尖离子流速；同时在干旱胁迫结束后，对油松和柴松根尖分别采用500 μmol/L质膜H⁺-ATP酶抑制剂原钒酸钠（sodium orthovanadate,Vanadate）预处理50 min、采用20 mmol/L质膜K⁺通道抑制剂氯化四乙胺（tetraethylammonium,TEA）预处理30 min、采用1 mmol/L质膜Ca²⁺通道抑制剂三氯化钆（Gadolinium chloride,GdCl₃）预处理1 h、采用5 μmol/L质膜Ca²⁺-ATP酶抑制剂Eosin yellow（Eosin-Y）预处理1 h，然后检测根尖K⁺流与Ca²⁺流。【结果】与对照相比，短期干旱胁迫对2种松树根、叶组织中K⁺、Ca²⁺含量影响不显著，但长期干旱胁迫下2种松树根、叶组织中K⁺、Ca²⁺含量显著减少，其中油松对K⁺、Ca²⁺的积累大于柴松。短期干旱胁迫诱导油松根尖K⁺从对照的轻微外排转为内流，长期干旱胁迫则增强K⁺外排流速；与对照相比，柴松在短期与长期干旱胁迫下K⁺外排均加强；对照条件下油松Ca²⁺内、外流基本平衡，短期胁迫下Ca²⁺内流加强，长期胁迫下在根尖伸长区Ca²⁺外排加强；柴松在短期与长期干旱胁迫下较对照不同程度地加强了Ca²⁺外排；油松根尖表皮细胞的K⁺和Ca²⁺内流速度均大于柴松。TEA显著抑制2种松树K⁺外流，但Vanadate显著促进2种松树K⁺外流，且其对柴松的影响没有油松显著；Eosin-Y可有效抑制2种松树Ca²⁺外排，但GdCl₃仅显著抑制油松Ca²⁺内流，对柴松Ca²⁺外流无效。【结论】油松通过较高的H⁺-ATP酶活性调控依赖去极化激活的离子通道限制K⁺外流，同时通过Ca²⁺ATP酶与Ca²⁺通道调控细胞Ca²⁺跨膜转运，在组织与根尖表皮细胞上减少K+流失并维持Ca²⁺平衡，因而较柴松抗旱性强。

关键词: 油松柴松干旱胁迫 K⁺流 Ca²⁺流

DOI：

分类号:

基金项目:中央高校基本科研业务费项目（2452015044）；西北农林科技大学博士科研启动基金资助项目（2013BSJJ049）；“十二五”农村领域国家科技支撑计划项目（2015BAD07B0203）

Effect of drought stress on potassium and calcium fluxes in Pinus tabulaeformis and Pinus tabulaeformis f.shekanensis

WANG Shuyuan,WANG Fu,TANG Jiaqi,et al

Abstract:

【Objective】The K⁺ and Ca²⁺ accumulation in roots and leaves and their transportation across plasma membrane of root tip epidermal cells of Pinus tabulaeformis and Pinus tabulaeformis f.shekanensis seedlings under drought stress were comparatively investigated,which would clarify the physiological differences between the two species in K⁺ and Ca²⁺ homeostasis perspective.【Method】Using the seedlings of the two species watered twice per week as control,five-month seedlings were treated with short-term (no watering for 7 d) and long term (no watering for 21 d) drought stresses.K⁺ and Ca²⁺ contents in root and leaf were measured by Atomic Absorption Spectrometry and K⁺ and Ca²⁺ fluxes from root tip were tested by Non-invasive Micro measurement Technique at the end of drought stress.Besides,the root tips were pretreated with 500 μmol/L sodium orthovanadate (Vanadate) as inhibitor of PM H⁺ ATPase for 50 min,20 mmol/L tetraethylammonium (TEA) as inhibitor of K⁺ channel for 30 min,1 mmol/L Gadolinium chloride (GdCl₃) as blocker of PM Ca²⁺ channel and 5 μmol/L Eosin yellow (Eosin-Y) as blocker of PM Ca²⁺ ATPase for 1 hour before testing K⁺ and Ca²⁺ fluxes.【Result】Compared with the control,the short-term drought stress had no effect on K⁺ and Ca²⁺ contentsin root and leaf of the two species,while the long-term stress induced the decrease of K⁺ and Ca²⁺ contents significantly with more K⁺ and Ca²⁺ accumulation in P.tabulaeformis.The short-term drought stress changed K⁺ in fluxes of P.tabulaeformis from slight K⁺ efflux under control,while the long-term stress enhanced K⁺ effluxes.Compared with the control,the K⁺ effluxes of P.tabulaeformis f.shekanensis were enhanced under both short-term and long-term stresses.Ca²⁺ fluxes of P.tabulaeformis were in balance under control,it increased under short-term stress and only increased in apical elongation zone under long-term stress.Ca²⁺ effluxes of P.tabulaeformis f.shekanensis were strenghthened differently under short-term stress and long-term stress,compared with the control.Both K⁺ and Ca²⁺ influxes of P.tabulaeformis were larger than that of P.tabulaeformis f.shekanensis.K⁺ effluxes were inhibited by TEA while strengthened by Vanadate in the two pines,and the effects were less significant in P.tabulaeformis f.shekanensis than P.tabulaeformis.The Ca²⁺ effluxes were inhibited by Eosin-Y in the two pines,and the Ca²⁺ in fluxes of P.tabulaeformis were inhibited by GdCl₃,which was not effective for P.tabulaeformis f.shekanensis.【Conclusion】K⁺ efflux was restricted through depolarization-activated K⁺ channel activated by higher active H⁺ATPase and Ca²⁺ was transported across plasma membrane by Ca²⁺ ATPase and Ca²⁺ channel,which reduced K⁺ loss and maintaining Ca²⁺ homeostasis both in cells and tissue of P.tabulaeformis.Therefore,P.tabulaeformis had higher drought-resistance than P.tabulaeformis f.shekanensis.

Key words: Pinus tabulaeformis Pinus tabulaeformis f.shekanensis drought stress K+ flux Ca2+ flux