Department of Botany, Savitribai Phule Pune University, Pune, India.
Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Trombay, Mumbai, India.
PLoS One. 2018 Apr 11;13(4):e0193394. doi: 10.1371/journal.pone.0193394. eCollection 2018.
Salinity is an important environmental constraint limiting plant productivity. Understanding adaptive responses of halophytes to high saline environments may offer clues to manage and improve salt stress in crop plants. We have studied physiological, biochemical and metabolic changes in a perennial, fast growing halophyte, Sesuvium portulacastrum under 0 mM (control), 150 mM (low salt, LS) and 500 mM (high salt, HS) NaCl treatments. The changes in growth, relative water content, cation, osmolyte accumulation, H2O2 and antioxidant enzyme activity (SOD, CAT and APX) were observed under different treatment conditions. A positive correlation was revealed for sodium ion accumulation with malondialdehyde (r2 = 0.77), proline (r2 = 0.88) and chlorophyll content (r2 = 0.82) under salt treatment while a negative correlation was observed with relative tissue water content (r2 = -0.73). The roots and leaves showed contrasting accumulation of potassium and sodium ions under LS treatment. Temporal and spatial study of sodium and potassium ion content indicated differential accumulation pattern in roots and leaves, and, high potassium levels in root. Higher H2O2 content was recorded in roots than leaves and the antioxidant enzyme activities also showed significant induction under salt treatment conditions. Gene expression profiling of sodium transporters, Sodium proton exchanger (NHX3), Vacuolar ATPase (vATPase) and Salt overly sensitive1 (SOS1) showed up regulation under salt stress after 6-24 hr of NaCl treatment. Metabolite changes in the salt stressed leaves showed increased accumulation of flavonoids (3,5-dihydroxy-6,4'-dimethoxy-flavone-7-O-[α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside], and3,5-dihydroxy-6,3',4'-trimethoxy-flavone-7-O-[α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside] in both LS and HS treatments, while a glycolipid, 1-O-linolenyl-2-O-(palmitoyl)-3-O-galactopyranosyl glycerol, accumulated more in LS over HS treatments and control. The results suggest that differential spatial and temporal cation levels in roots and leaves, and accumulation of flavanoid and glycolipid could be responsible for salt adaptation of S. portulacastrum.
盐度是限制植物生产力的重要环境限制因素。了解盐生植物对高盐环境的适应反应，可能为管理和改善作物的盐胁迫提供线索。我们研究了多年生、快速生长的盐生植物海蓬子在 0 mM（对照）、150 mM（低盐，LS）和 500 mM（高盐，HS）NaCl 处理下的生理、生化和代谢变化。在不同处理条件下观察了生长、相对水含量、阳离子、渗透物积累、H2O2 和抗氧化酶活性（SOD、CAT 和 APX）的变化。在盐处理下，钠离子积累与丙二醛（r2 = 0.77）、脯氨酸（r2 = 0.88）和叶绿素含量（r2 = 0.82）呈正相关，而与相对组织水含量（r2 = -0.73）呈负相关。LS 处理下，根和叶中钾离子和钠离子的积累表现出相反的模式。钠离子和钾离子含量的时空研究表明，根和叶中存在不同的积累模式，根中钾离子水平较高。根中记录到的 H2O2 含量高于叶，抗氧化酶活性在盐处理条件下也显著诱导。盐胁迫 6-24 小时后，钠离子转运体、钠离子-质子交换器（NHX3）、液泡 ATP 酶（vATPase）和盐过度敏感 1（SOS1）的基因表达谱显示上调。盐胁迫下叶片代谢物变化显示，黄酮类（3,5-二羟基-6,4'-二甲氧基黄酮-7-O-[α-L-鼠李吡喃糖基-（1→6）-β-D-吡喃葡萄糖苷]和 3,5-二羟基-6,3',4'-三甲氧基黄酮-7-O-[α-L-鼠李吡喃糖基-（1→6）-β-D-吡喃葡萄糖苷]在 LS 和 HS 处理中均有增加，而 1-O-亚油酰基-2-O-（棕榈酰基）-3-O-半乳糖吡喃基甘油这种糖脂在 LS 中比 HS 处理和对照中积累更多。结果表明，根和叶中阳离子的时空差异水平以及黄酮类和糖脂的积累可能是海蓬子盐适应的原因。
