Abstract Gradual soil-salinization is enhancing the proportion of non-arable salinized land areas. Developing strategies to utilize salinized lands for balanced economical productivity are highly desirable. Salt-tolerating Pongamia pinnata has gained significant attraction as a potential biofuel tree species and hence, could act as an efficient energy- crop alternative for cultivation in salinized lands. However, mechanisms conferring salt-tolerance to Pongamia are not yet demonstrated. It is highly crucial to understand the tolerance mechanisms for future breeding purposes for enhanced productivity under saline conditions. Hydroponically grown 30 days old seedlings of Pongamia are treated with two different salt concentrations (300 and 500 mM NaCl) for 8 days and analysed at regular intervals of 1, 4 and 8 days after salt exposure. Physiological parameters were recorded using infrared gas analyser and portable mini-PAM. Ion (Na+, K+, Cl−, and Ca2+) accumulation in leaves and roots were analysed through atomic absorption spectroscopy and Na+ localization was tracked through confocal laser scanning microscopy. Histochemical detection of lignin and suberin depositions in leaves and roots were carried out. Pongamia roots act as ultra-filters/strong barriers to avoid accumulation of excess Na+ levels in the leaves. The Na+ probe fluorescence analysis demonstrated effective vacuolar sequestration of Na+ in the roots. Formation of suberized multiseriate exodermis in the roots, along with extensive lignification maximized water permeability in both leaves and the roots. The present study clearly demonstrates the key cellular mechanisms conferring salinity tolerance in P. pinnata, which can be sustainably grown in salinized marginal lands as a potential biofuel tree species.

中文翻译：

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疏水性细胞壁屏障和 Na+ 离子的液泡隔离是赋予生物燃料树种 Pongamia pinnata L. pierre 高盐度耐受性的关键机制之一

摘要 土壤逐渐盐渍化正在增加非耕地盐渍化土地面积的比例。非常需要制定利用盐渍化土地平衡经济生产力的策略。耐盐水黄作为一种潜在的生物燃料树种已经获得了极大的吸引力，因此可以作为一种有效的能源作物替代品在盐渍化土地上种植。然而，尚未证明赋予水黄属耐盐性的机制。了解未来育种目的的耐受机制以提高盐渍条件下的生产力非常重要。用两种不同的盐浓度（300 和 500 mM NaCl）将水培生长的 30 天龄水黄幼苗处理 8 天，并在接触盐后的 1、4 和 8 天定期进行分析。使用红外气体分析仪和便携式微型 PAM 记录生理参数。通过原子吸收光谱分析了叶和根中离子（Na+、K+、Cl-和Ca2+）的积累，并通过共聚焦激光扫描显微镜跟踪了Na+的定位。进行了叶和根中木质素和木栓质沉积的组织化学检测。水黄根充当超滤器/强屏障，以避免在叶子中积累过多的 Na+ 水平。Na + 探针荧光分析证明了根中 Na + 的有效液泡螯合。根中木栓化多列外皮的形成以及广泛的木质化使叶和根中的水渗透性最大化。本研究清楚地证明了赋予 P. pinnata 耐盐性的关键细胞机制，