Post Graduate Department of Biotechnology, St. Xavier's College (Autonomous), 30, Mother Teresa Sarani, Kolkata, West Bengal, 700016, India.
Environ Sci Pollut Res Int. 2019 Dec;26(36):36598-36614. doi: 10.1007/s11356-019-06711-9. Epub 2019 Nov 16.
The manuscript illustrates the ameliorative effects of exogenously applied higher polyamine (PA), spermidine (Spd) in the susceptible indica rice cultivar IR-64 subjected to prolonged fluoride stress. The Spd treatment drastically reduced fluoride bioaccumulation by restricting entry of the anions through chloride channels and enabled better maintenance of the proton gradient via accumulation of P-H/ATPase, thereby improving the root and shoot lengths, fresh and dry weights, RWC, chlorophyll content and activities of pyruvate dehydrogenase (PyrDH), α-amylase, and nitrate reductase (NR) in the Spd-treated, stressed plants. Expression of RuBisCo, PyrDH, α-amylase, and NR was stimulated. Spd supplementation reduced the molecular damage indices like malondialdehyde, lipoxygenase, protease activity, electrolyte leakage, protein carbonylation, HO, and methylglyoxal (detoxified by glyoxalase II). Mitigation of oxidative damage was facilitated by the accumulation and utilization of proline, glycine-betaine, total amino acids, higher PAs, anthocyanin, flavonoids, β-carotene, xanthophyll, and phenolics as verified from the expression of genes like P5CS, BADH1, SAMDC, SPDS, SPMS, DAO, PAO, and PAL. Spd treatment activated the ascorbate-glutathione cycle in the stressed seedlings. Expression and activities of enzymatic antioxidants showed that GPOX, APX, GPX, and GST were the chief ROS scavengers. Exogenous Spd promoted ABA accumulation by upregulating NCED3 and suppressing ABA8ox1 expression. ABA-dependent osmotic stress-responsive genes like Osem, WRKY71, and TRAB1 as well as ABA-independent transcription factor encoding gene DREB2A were induced by Spd. Thus, Spd treatment ameliorated fluoride-mediated injuries in IR-64 by restricting fluoride uptake, refining the defense machinery and activating the ABA-dependent as well as ABA-independent stress-responsive genes.
该手稿说明了外源施加较高浓度多胺（腐胺）在延长氟胁迫下敏感籼稻品种 IR-64 中的改善作用。腐胺处理通过限制阴离子通过氯离子通道进入来大幅减少氟的生物积累，并通过积累 P-H/ATP 酶来更好地维持质子梯度，从而改善了根和茎的长度、鲜重和干重、RWC、叶绿素含量以及丙酮酸脱氢酶（PyrDH）、α-淀粉酶和硝酸还原酶（NR）的活性在 Spd 处理的胁迫植物中。RuBisCo、PyrDH、α-淀粉酶和 NR 的表达受到刺激。腐胺补充减少了丙二醛、脂氧合酶、蛋白酶活性、电解质渗漏、蛋白质羰基化、HO 和甲基乙二醛（由甘油醛二磷酸酶 II 解毒）等分子损伤指数。脯氨酸、甘氨酸甜菜碱、总氨基酸、高多胺、花青素、类黄酮、β-胡萝卜素、叶黄素和酚类物质的积累和利用促进了氧化损伤的缓解，这从 P5CS、BADH1、SAMDC、SPDS、SPMS、DAO、PAO 和 PAL 等基因的表达中得到证实。腐胺处理激活了胁迫幼苗中的抗坏血酸-谷胱甘肽循环。酶抗氧化剂的表达和活性表明 GPOX、APX、GPX 和 GST 是主要的 ROS 清除剂。外源腐胺通过上调 NCED3 和抑制 ABA8ox1 表达促进 ABA 积累。ABA 依赖的渗透胁迫响应基因如 Osem、WRKY71 和 TRAB1 以及 ABA 独立的转录因子编码基因 DREB2A 被腐胺诱导。因此，腐胺处理通过限制氟的摄取、完善防御机制以及激活 ABA 依赖和 ABA 独立的应激响应基因来改善氟介导的 IR-64 损伤。
