外源亚精胺对As5+胁迫下水稻种子萌发和As吸收积累的影响

农田As污染对农作物生长有毒害作用,导致农作物产量降低、品质下降.研究了外源添加亚精胺(Spd)对As~(5+)胁迫下水稻种子萌发和幼苗生长的影响.结果表明,外源添加Spd能够促进As~(5+)胁迫下水稻种子的萌发过程,提高种子的发芽势和发芽率,促进幼苗根系生长.添加Spd可以不同程度地提高As~(5+)胁迫下水稻幼苗和根系中的抗氧化酶系统过氧化氢酶(CAT)、过氧化物酶(POD)和超氧化物歧化酶(SOD)的活性,降低水稻幼芽和根系中的丙二醛(MDA)含量.当As~(5+)浓度为25μmol·L~(-1)时,添加500μmol·L~(-1)和1 000μmol·L~(-1) Spd使水稻根系中的MDA含量比对照处理分别降低12.3%和31.3%,水稻幼芽CAT活性分别提高105.1%和101.4%,水稻根系CAT活性分别提高29.9%和57.1%.添加Spd也影响水稻对As的吸收积累.当As~(5+)浓度为25μmol·L~(-1)时,添加500μmol·L~(-1)和1 000μmol·L~(-1) Spd导致水稻幼芽As含量与对照相比分别降低69.4%和75.1%,水稻根系As含量分别降低7.6%和24.4%.Spd可以有效地缓解As~(5+)对水稻的毒害作用.     

外源亚精胺调控黑麦草根系响应镉胁迫及其转录组学分析

应用外源生长调节物质是增强植物抗逆能力的有效手段之一.以黑麦草为受试植物,进行水培试验,探究外源基施0.1 mmol ·L^-1亚精胺（Spd）对不同水平（0、5和10 mg ·L^-1）镉（Cd）胁迫下黑麦草根系生理学和分子生物学两方面的影响.生理学研究结果表明,Cd胁迫显著降低黑麦草根系的生理机能,而添加Spd可有效缓解Cd引起的负面作用.其中对根系可溶性蛋白含量的影响最为显著,较5 mg ·L^-1和10 mg ·L^-1 Cd单独处理,分别提高了90.91%和158.35%.Spd还通过提高抗坏血酸（ASA）和谷胱甘肽（GSH）含量、过氧化物酶（POD）活性来抑制氧化胁迫产物丙二醛（MDA）和过氧化氢（H₂O₂）的积累,对根系活力和超氧化物歧化酶（SOD）活性的影响则不显著.分子生物学研究结果表明,10 mg ·L^-1Cd胁迫致使黑麦草根部大量基因发生了差异表达,应用外源Spd后差异表达基因的数目、差异显著性和差异倍数均显著降低,GO富集分析最显著的部分由响应有机环状化合物、醛基/酮基转移酶活性变为响应三价铁离子和2''-脱氧麦根酸2''-双加氧酶活性.单基因表达热图分析发现,外源Spd上调了锌铁转运蛋白和2''-脱氧麦根酸2''-双加氧酶相关基因的表达,提高了根系对铁的吸收利用能力.综上所述,施用一定浓度的Spd可有效调控黑麦草根系对Cd胁迫的响应,增强其耐性生理,减轻Cd的毒害效应.     

Epibrassinolide ameliorates Cr (VI) stress via influencing the levels of indole-3-acetic acid, abscisic acid, polyamines and antioxidant system of radish seedlings

The present investigation determined the effects of epibrassinolide (EBL) on the levels of indole-3-acetic acid (IAA), abscisic acid (ABA), and polyamine (PA) and antioxidant potential of 7-d old Raphanus sativus L. cv. ‘Pusa chetki’ seedlings grown under Cr (VI) metal stress. Reduced titers of free (0.767 μg g⁻¹ FW) and bound (0.545 μg g⁻¹ FW) IAA in Cr (VI) stressed seedlings were observed over untreated control. Supplementations of EBL to Cr (VI) stressed seedlings were able to enhance both free (2.14-5.68 μg g⁻¹ FW) and bound IAA (2.45-7.78 μg g⁻¹ FW) concentrations in comparison to Cr (VI) metal treatment alone. Significant rise in free (13.49 μg g⁻¹ FW) and bound (12.17 μg g⁻¹ FW) ABA contents were noticed for Cr (VI) stressed seedlings when compared to untreated control. No significant increase in ABA contents were recorded for Cr (VI) stressed seedlings upon supplementation with EBL over Cr (VI) treatment alone. A significant increase in Put (18.40 μg g⁻¹ FW) and Cad (9.08 μg g⁻¹ FW) contents were found for 10⁻⁹ M EBL plus Cr (VI) metal treatments when compared to Cr (VI) treatment alone. Spermidine (Spd) contents were found to decline significantly for EBL treatment alone or when supplemented with Cr (VI) treatments over untreated controls and Cr (VI) treatment alone. Antioxidant levels were found to enhance, with glutathione (57.98 mg g⁻¹ FW), proline (4.97 mg g⁻¹ FW), glycinebetaine (39.01 μmol mL⁻¹), ascorbic acid (3.17 mg g⁻¹ FW) and phytochelatins (65.69 μmol g⁻¹ FW) contents noted for EBL supplemented to Cr (VI) metal solution over Cr (VI) treatment alone. Reduced activities of guaiacol peroxidase (0.391 U mg⁻¹ protein) and catalase (0.221 U mg⁻¹ protein) and enhanced activities of glutathione reductase (7.14 U mg⁻¹ protein), superoxide dismutase (15.20 U mg⁻¹ protein) and ascorbate peroxidase (4.31 U mg⁻¹ protein) were observed in seedlings treated with EBL plus Cr (VI) over Cr metal treatment alone. Reduced MDA (2.55 μmol g⁻¹ FW) and H₂O₂ (33.24 μmol g⁻¹ FW) contents were recorded for 10⁻⁹ M EBL supplemented to Cr (VI) stress over Cr (VI) treatment alone. Enhancement in free radical scavenging potential as indicated by higher values of 1,1-diphenylpicrylhydrazyl, deoxyribose and reducing power activity assays, and increased levels of phenols and soluble sugars also showed significant influence of EBL in alleviating Cr (VI) stress in radish seedlings.     

铅胁迫下黄瓜幼苗内源多胺变化动态的初步研究

以黄瓜幼苗为材料,采用高效液相色谱法测定黄瓜幼苗叶和茎中内源多胺的含量,研究了铅胁迫下黄瓜幼苗生长及内源多胺的变化。结果表明:铅质量浓度为100mg·L-1时促进黄瓜幼苗的生长,铅质量浓度高于100mg·L-1时,黄瓜幼苗茎高和根长逐渐下降;铅胁迫下黄瓜幼苗地上部的腐胺含量明显高于对照值,且随着铅质量浓度增加和处理时间的延长呈下降趋势。黄瓜幼苗叶片精胺和亚精胺在处理第5d时高于对照值,茎中精胺和亚精胺含量在处理第7d高于对照值,而其它时间内的都低于对照值,而且其含量均随铅质量浓度的增加而呈下降趋势;过氧化物酶活性变化与内源多胺含量(腐胺、精胺和亚精胺之和)的变化相似,表明铅胁迫能改变黄瓜幼苗内源多胺的含量和调节过氧化物酶活性,从而影响着黄瓜植株的生长。