人工纳米材料增强植物耐盐性的机理研究

Mechanisms of Plant Salt Tolerance Promoted by Nanomaterials

土地盐渍化问题导致土壤环境恶化和农作物减产,基于纳米材料(NMs)的纳米农业技术在增强植物耐盐性方面的潜力正备受关注.目前,关于NMs提高植物耐盐性的分子机制仍不明确,因此以烟草(Nicotiana tabacum L.)BY-2悬浮细胞为供试材料,研究对照组(CK)、盐胁迫处理组(S)以及盐胁迫下分别暴露于纳米二氧化钛(nTiO_(2))和纳米硒(nSe)的细胞活性变化,并通过非损伤微测系统(NMT)原位实时检测Na+流速,采用液相色谱质谱联用(LC-MS/MS)技术分析NMs对盐胁迫下烟草BY-2悬浮细胞代谢组的影响.结果表明:①0.1 mg/L nTiO_(2)(处理6 h)与0.5 mg/L nSe(处理12 h)使盐胁迫下的烟草BY-2悬浮细胞的活性分别显著提高8.1%和13.6%.②0.1 mg/L nTiO_(2)(处理6 h)与0.5 mg/L nSe(处理12 h)使盐胁迫下的烟草BY-2悬浮细胞的Na+外排也分别显著增加了171.5%和99.0%.③两种NMs通过调控不同的代谢通路增强烟草BY-2悬浮细胞的耐盐能力.烟草BY-2悬浮细胞暴露于0.1 mg/L nTiO_(2)(处理6 h)和0.5 mg/L nSe(处理12 h)后分别识别出53种和73种差异代谢物,nTiO_(2)可增强多种类别代谢物〔部分氨基酸和肽、脂肪酸和共轭物、三羧酸循环(TCA cycle)有机酸、糖类和嘧啶等物质〕的合成,而nSe则主要增强氨基酸和肽、吲哚和水杨酸等物质的合成.④暴露于nTiO_(2)后,烟草BY-2悬浮细胞产生的差异代谢物中尿苷、吡哆醛、甘露糖、大麦芽碱和葫芦巴碱等代谢物含量均与Na+外排呈显著正相关;暴露于nSe后,烟草BY-2悬浮细胞产生的差异代谢物中吲哚丙烯酸、色氨酸、苯丙氨酸、酪氨酸等代谢物含量均与Na+外排呈显著正相关,这些物质多参与莽草酸代谢通路,因此nSe可能通过调控莽草酸途径增强Na+外排.研究显示,0.1 mg/L nTiO_(2)与0.5 mg/L nSe分别通过不同的代谢途径增强烟草BY-2细胞的耐盐性.

Land salinization leads to reduction in crop yield and degradation of soil environment.Nanomaterials(NMs),emerging for nano-based agriculture,have great potential to improve plant saline tolerance.However,there is a lack of knowledge of the molecular mechanisms of the nano-stimulated plant saline tolerance.In this study,salt-stressed(100 mmol/L NaCl)tobacco(Nicotiana tabacum L.)BY-2 cell suspensions were exposed to nano-TiO_(2)(nTiO_(2))or nano-Se(nSe),and cell viability was measured to evaluate the salt tolerance induced by nanomaterials.Non-invasive Micro-test Technology(NMT)was used to detect the net flux of Na+,and liquid chromatographytandem-mass spectrometry(LC-MS/MS)was used to reveal the effects of nanomaterials on the metabolomics of tobacco BY-2 cell suspensions under salt stress.The results showed that:(1)0.1 mg/L nTiO_(2)(6 h)and 0.5 mg/L nSe(12 h)significantly increased the viability of salt stressed tobacco BY-2 cell suspensions at 6 h(8.1%)and 12 h(13.6%),respectively.(2)0.1 mg/L nTiO_(2)(6 h)and 0.5 mg/L nSe(12 h)also significantly increased the extrusion of Na+by 171.5%and 99.0%,respectively.(3)At the metabolomics level,different metabolic pathways were involved in nTiO_(2) or nSe-regulated salt tolerance of tobacco BY-2 cell suspensions.Specifically,exposure to 0.1 mg/L nTiO_(2) for 6 h or 0.5 mg/L nSe for 12 h of led to alterations in 53 and 73 different metabolites,respectively.nTiO_(2) enhanced the synthesis of many different classes of metabolites(some amino acids and peptides,fatty acids and conjugates,tricarboxylic acid cycle(TCA cycle)organic acids,sugars and pyrimidines,etc.),while nSe mainly increased the synthesis of amino acids and peptides,indole and salicylic acid.(4)In addition,in salt-stressed tobacco BY-2 cell suspensions exposed to nTiO_(2),the amounts of uridine,pyridoxal,mannose,hordenine and trigonelline were significantly correlated with Na+efflux.Meanwhile,the amounts of indoleacrylic acid,tryptophan,phenylalanine,tyrosine and acetylarginine were significantly correlated with Na+efflux after nSe exposure,implying that the shikimic acid pathway could contribute to the nSe-induced salt tolerance.These findings show that nTiO_(2) and nSe improve plant salt tolerance by different metabolic pathways.