Abstract

Salt stress induced modulations in different ionic ratios and ROS system were studied in ten halophytic species, namely Atriplex lentiformis, Tamarix aphylla, Sporobolus marginatus, Suaeda nudiflora, Urochondra setulosa, Arundo donax, Aeluropus lagopoides, Heliotropium ramossimum, Atriplex nummularia, Leptachloa fusca at salinity level of ECe ∼ 30 dSm⁻¹ (≈300 mM NaCl) to explore their possible role in salt tolerance ability of these halophytes. These halophytes were categorized for their salt tolerance levels based on the ratios of Na⁺/K⁺, Na⁺/Ca²⁺, Na⁺/Cl⁻ and Na + Cl/K + Ca. Variable responses were observed among all halophytes where Atriplex lentiformis had lowest leaf Na⁺/K⁺ (0.44) which is one of the best indicator of salt tolerance, Heliotropium ramossimum had lowest Na⁺/Ca²⁺ and Na⁺/Cl⁻ (0.97 and 0.18), whereas Sporobolus marginatus had lowest Na + Cl/K + Ca (0.79). Specific enzymes activities of ascorbate peroxidase (APX), superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX) were also assessed to get better comprehension of the ROS scavenging system under salinity in these halophytes. Urochondra setulosa showed highest APX and SOD activity followed by Atriplex lentiformis. Most efficient enzyme in degrading hydrogen peroxide i.e. CAT showed highest activity in Suaeda nudiflora followed by Atriplex nummularia and Urochondra setulosa, whereas Atriplex nummularia and Atriplex lentiformis showed higher POX activity. Significant variability in H₂O₂ and MDA content was also observed. These results possibly suggest higher inbuilt genetic potential of these halophytes to combat high salinity induced oxidative stress via higher antioxidant activities.

Novelty statement: Halophytic plant adopt different strategies to cope up with the toxic ions and our studies show that the induction of antioxidant defense system to scavenge ROS, alongwith structural modifications in terms of lipid peroxidation and compartmentalization of toxic ions are the main strategies for tighter control of ion fluxes in the studied halophytes.

摘要

在不同的离子的比率和ROS系统盐胁迫诱导的调制在10盐生种，即进行了研究藜lentiformis，无叶柽柳，鼠尾marginatus，碱蓬裸花，Urochondra setulosa，芦竹，獐lagopoides，天芥菜属ramossimum，大洋洲滨藜，Leptachloa裂孢菌在盐度ECe〜30 dSm ^-1（≈300mM NaCl）的水平，以探讨它们在这些盐生植物耐盐能力中的可能作用。这些盐生植物是基于Na比值归类为他们的盐耐受性水平⁺ / K ⁺，钠⁺ /钙²⁺，钠⁺ /氯^-Na + Cl / K +Ca。所有盐生植物，其中中观察到可变响应滨藜lentiformis有最低叶的Na ⁺ / K ⁺（0.44），这是耐盐性的最佳指标之一，天芥菜属ramossimum有最低的Na ⁺ /钙²⁺和Na ⁺ /氯^-（0.97和0.18），而孢粉边缘具有最低的Na + Cl / K + Ca（0.79）。还评估了这些盐生植物在盐度下抗坏血酸过氧化物酶（APX），超氧化物歧化酶（SOD），过氧化氢酶（CAT）和过氧化物酶（POX）的特定酶活性，以更好地理解ROS清除系统。Urochondra setulosa表现出最高的APX和SOD活性，其次是滨藜。降解过氧化氢的最有效酶即CAT在Suaeda nudiflora中显示最高活性，其次为Atriplex nummularia和Urochondra setulosa，而Atriplex nummularia和Atriplex lentiformis显示更高的POX活性。还观察到H ₂ O ₂和MDA含量的显着变化。这些结果可能表明这些盐生植物具有更高的内在遗传潜力，以通过更高的抗氧化剂活性来对抗高盐度诱导的氧化胁迫。

新颖性声明：盐生植物采用不同的策略来应对有毒离子，我们的研究表明，诱导抗氧化剂防御系统清除ROS，以及脂质过氧化和有毒离子的区室化方面的结构修饰是更严格控制的主要策略盐生植物中离子通量的分布。