Phytohormone involved in salt tolerance regulation of Elaeagnus angustifolia L. seedlings

Soil salinization is a serious problem for plant growth worldwide. Understanding the tolerance mechanisms of salt-tolerant plants is essential for development and utilization of saline-alkali land. The salt-tolerant tree species Elaeagnus angustifolia is utilized in landscaping and ecological restoration projects such as afforestation. In this work, we examined the changes in phytohormone levels and the expression of phytohormone-related genes in E. angustifolia seedlings under salt stress. We observed no changes in the biomass, leaf area, and the size of epidermal cells of E. angustifolia seedlings under low levels of NaCl (50 mM); however, when the NaCl concentration was increased, these parameters were significantly reduced. Comparison of the transcriptome data of the species seedlings under 0 and 150 mM NaCl showed that many hormone pathways are involved in the salt-tolerance response. Under salt stress, abscisic acid (ABA) and jasmonate (JA) contents increased significantly, whereas the contents of auxin (IAA), gibberellin (GA), cytokinins (CKs), and brassinosteroids (BRs) decreased significantly. We conclude that these changes could be responsible for the growth inhibition and increased salt resistance of E. angustifolia seedlings.土壤盐渍化是全球范围内制约植物生长的严峻问题。解析耐盐植物的耐盐机制，对于盐碱地的开发与利用至关重要。沙枣（Elaeagnus angustifolia）作为耐盐树种，被广泛应用于园林绿化及造林等生态修复工程中。本研究针对盐胁迫下沙枣幼苗的植物激素水平变化及激素相关基因的表达情况展开分析。实验结果显示，在低浓度NaCl（50 mM）处理下，沙枣幼苗的生物量、叶面积以及表皮细胞大小均无显著变化；而当NaCl浓度升高时，上述指标均显著降低。通过对比0 mM与150 mM NaCl处理下沙枣幼苗的转录组数据，发现多条激素通路参与了耐盐响应过程。盐胁迫下，脱落酸（abscisic acid, ABA）与茉莉酸（jasmonate, JA）的含量显著升高，而生长素（auxin, IAA）、赤霉素（gibberellin, GA）、细胞分裂素（cytokinins, CKs）以及油菜素甾醇（brassinosteroids, BRs）的含量则显著降低。本研究表明，上述激素水平的变化可能是沙枣幼苗生长受抑制但耐盐性增强的原因。