多胺对小麦耐铝性的调控作用及其机理

发布时间：2018-05-12 16:37

本文选题：铝毒 + 小麦　；参考：《浙江大学》2016年博士论文

【摘要】：全球约30%的土地面积和50%的潜在可耕地面积为pH低于5.5的酸性土壤。在我国,酸性土壤约占全国土地面积的22.7%。铝毒被认为是酸性土壤上限制作物生长最重要的障碍因子,它首先抑制根系伸长,进而抑制根系对水分和养分的吸收,降低酸性土壤上农作物的产量和品质。关于植物铝毒害和耐性机制已有大量研究,但是对植物铝毒胁迫适应过程中的信号调控机制尚不完全清楚。多胺是一类低分子量脂肪族含氮碱,参与了植物对逆境胁迫响应的信号调控过程,但是关于多胺在植物铝胁迫响应的调控机制尚不清楚。本论文以西矮麦1号(耐铝基因型)和扬麦5号(铝敏感基因型)为材料,围绕铝胁迫下根尖内源多胺的含量和形态变化、铝诱导的游离态腐胺(Put)积累对根尖细胞壁性质的影响、Put对铝胁迫下根尖多胺氧化酶活性的影响、Put对铝胁迫下根尖乙烯产生的影响、铝诱导的束缚态Put积累等过程及其与小麦耐铝性的关系进行了研究。取得的主要结果如下：(1)本试验研究了铝胁迫下2个小麦基因型根尖多胺种类、形态和含量以及ROS产生、氧化损伤程度和根系伸长的变化。结果表明,随着铝处理浓度的提高和时间的延长根系伸长逐渐降低,但西矮麦1号显著高于扬麦5号。30μM铝处理24 h后,2个小麦基因型根尖铝含量以及H2O2、O2·-、ROS、MDA、Evens blue吸收量及染色程度均显著升高,扬麦5号显著高于西矮麦1号。铝胁迫下西矮麦1号根尖Put总量、游离态、结合态和束缚态Put含量均随铝处理时间延长而有不同程度的增加；而扬麦5号根尖Put总量和游离态Put含量仅在12h后增加且增幅小于西矮麦1号,其结合态Put变化与西矮麦相似,束缚态Put含量则无明显变化。相反,西矮麦1号和扬麦5号根尖总Spd和游离态Spd令量均随铝处理时间延长而显著降低,且后者降幅较大；二者根尖结合态和束缚态Spd含量均无显著变化。铝胁迫下根尖精氨酸脱羧酶(ADC)活性显著升高,添加ADC竞争性抑制剂(D-Arg)加剧了铝诱导的氧化损伤,且对西矮麦1号毒害尤为严重。因此,铝诱导依赖于ADC的游离态Put含量增加及其向束缚态的转化是小麦耐铝性的重要机制,而游离态Spd含量降低可能与小麦铝敏感性有关。(2)通过Put及其合成抑制剂处理,研究了铝诱导积累的游离态Put对根尖细胞壁组分和性质的影响及其与耐铝性的关系。结果表明,外源Put处理可显著增加2个小麦基因型根尖游离态Put含量,缓解铝对小麦根系伸长的抑制,降低根尖细胞壁铝含量,且对扬麦5号缓解效果更显著。而添加ADC抑制剂(D-Arg)在抑制Put合成的同时加剧了铝对耐性基因型根系伸长的抑制及铝在根尖的积累。Put及其合成抑制剂(D-Arg)对铝胁迫下小麦根系苹果酸分泌及根际pH均无显著影响。铝胁迫下扬麦5号根尖细胞壁果胶、半纤维素1和2的含量显著增加,果胶甲酯化程度显著降低；而西矮麦1号根尖果胶含量无显著变化,半纤维素1和2增幅及果胶甲酯化程度降幅较小。D-Arg处理进一步增加了铝胁迫下细胞壁各组分含量及果胶去甲酯化程度。Put处理则显著降低了2个小麦基因型根尖细胞壁各组分的含量,增加了果胶甲酯化程度,且在扬麦5号中更为显著。免疫荧光定位的结果也表明,Put处理显著提高了小麦根尖高甲酯化程度果胶含量,降低了甲酯化程度果胶含量。表明,铝胁迫下依赖于ADC的Put积累可通过降低细胞壁多糖含量,增加果胶甲酯化程度,减少铝在细胞壁的积累,从而增强小麦的耐铝性。(3)采用Put和胺氧化酶抑制剂等药理学方法,研究了铝胁迫下小麦根尖多胺氧化分解与氧化胁迫的关系以及Put的调控作用。结果表明,铝胁迫下扬麦5号根尖MDA、Evens blue吸收量以及脂氧合酶活性显著高于西矮麦1号；而Put和多胺氧化酶(PAO)抑制剂(GZT、DADD)可显著缓解铝引起的氧化损伤。对胺氧化酶活性的测定和亚细胞定位结果显示,铝胁迫下扬麦5号根尖细胞壁结合态PAO活性在铝处理3h显著提高,且随处理时间的延长逐渐增加,而西矮麦1号则变化幅度较小。铝胁迫下根尖H202的产生与细胞壁结合态PAO活性的变化趋势相似,外源添加Put和PAO抑制剂(GZT、DADD)可显著降低H202的积累,且在扬麦5号中效果更显著。Put可显著抑制NADPH氧化酶活性,但PAO抑制剂(GZT、DADD)对其无显著影响。可见,除了质膜NADPH氧化酶外,细胞壁结合态PAO也是铝胁迫下小麦根尖H202的重要来源。Put通过抑制细胞壁结合态PAO和质膜NADPH氧化酶活性,进而降低H202水平和氧化胁迫程度,从而缓解铝对小麦的毒害。(4)运用Put、乙烯供体及其合成或识别相关抑制剂,研究了Put对铝胁迫下不同耐铝基因型小麦根尖乙烯释放的调控作用及其机理。结果表明,Put可有效缓解铝对小麦根系生长的抑制,且在扬麦5号中效果更显著。乙烯供体(乙烯利、ACC)加剧了铝对根系伸长的抑制程度,乙烯合成抑制剂(AVG、CoCl2)及识别阻断剂(AgNO3)则显著缓解了铝对根系伸长的抑制。根尖乙烯释放对铝胁迫响应具有显著的基因型差异,敏感基因型在铝胁迫1h根尖乙烯释放速率显著增加,且在3h达到峰值,而耐铝基因型根尖乙烯响应时间晚且释放速率较小。Put和乙烯合成抑制剂(AVG、CoCl2)可显著抑制铝诱导的乙烯释放,且扬麦5号的降幅更大。铝处理3h后小麦根尖ACC合成酶(ACS)和ACC氧化酶(ACO)活性均显著增加,且扬麦5号增幅更大；Put处理显著抑制了ACS的活性及其产物ACC的含量,但对ACO活性无显著影响。表明,铝胁迫下根尖乙烯的快速释放是小麦根系伸长受铝抑制的重要原因,Put可通过抑制乙烯合成关键酶ACS的活性,减少铝诱导的乙烯释放,缓解铝对小麦根系伸长的抑制。(5)通过转谷酰胺酶(束缚态Put合成的关键酶)专一性抑制剂菲咯啉(o-phen)处理,研究了铝胁迫下小麦根尖束缚态Put对抗氧化酶的调控作用及其与耐铝性的关系。结果表明,铝胁迫下西矮麦1号根尖束缚态Put含量显著提高,而扬麦5号中无明显变化；o-phen可显著降低西矮麦1号根尖束缚态Put的积累。铝胁迫下西矮麦1号根尖ROS积累、细胞膜透性、膜脂过氧化、蛋白质氧化、胼胝质积累以及根系伸长受抑的程度显著轻于扬麦5号,而o-phen处理显著加剧了西矮麦1号根尖ROS积累和氧化损伤程度。铝胁迫诱导西矮麦1号和扬麦5号根尖SOD、CAT和APX等抗氧化酶活性提高,但前者显著高于后者；外源o-phen处理后西矮麦1号根尖SOD、CAT、APX活性显著降低,但扬麦5号无显著变化。表明,铝诱导产生的束缚态Put主要通过增强根尖抗氧化酶活性,降低ROS的积累,从而减轻铝胁迫导致的氧化损伤对小麦根系伸长的抑制。
[Abstract]:The effect of Put on root tip polyamine oxidase activity , the effect of Put on root tip polyamine oxidase activity , the effect of Put on root tip polyamine oxidase activity under aluminum stress , the effect of Put on root tip polyamine oxidase activity , the effect of Put on root tip polyamine oxidase activity under aluminum stress , the effect of Put on root tip polyamine oxidase activity , the effect of Put on root tip polyamine oxidase activity under aluminum stress , the effect of Put on root tip polyamine oxidase activity under aluminum stress , and the effect of Put on root tip polyamine oxidase activity under aluminum stress were studied .
In contrast , both the total Spd and the free Spd in the apical total Spd and the free Spd of Yangmai No . 1 and Yangmai 5 decreased significantly with the time of aluminum treatment , and the latter decreased greatly .
The effect of aluminium on root elongation of wheat roots and its relationship with aluminium resistance were studied . The results showed that the addition of D - Arg could increase the content of root elongation of wheat root tip and decrease the content of root tip cell wall aluminium . The results showed that the content of free Put and its synthesis inhibitor ( D - Arg ) could increase the root elongation of wheat root tip and the accumulation of aluminium in root tip .
The results showed that the content of Pectin in the apical cell wall of wheat genotypes was increased , the content of methyl ester was increased , and the content of Pectin methyl ester was increased . The results of immunofluorescence showed that the content of Pectin in the apical cell wall of wheat was increased , the content of methyl ester was increased , and the content of Pectin methyl ester was decreased .
The effect of Put and Polyamine Oxidase ( GZT , DADD ) on root elongation of wheat under aluminum stress was observed .
The results showed that the fast release of root tip ethylene under aluminum stress was the important reason for the elongation of wheat root elongation under aluminum stress .
o - phen can significantly reduce the accumulation of putput in the root tip of short wheat 1 . Under aluminum stress , the accumulation of ROS , membrane permeability , membrane lipid peroxidation , protein oxidation , callose accumulation and root elongation are significantly less than that of Yangmai 5 , while o - phen treatment significantly increases the accumulation and oxidative damage degree of root tip ROS of Xai wheat No . 1 . The activities of antioxidant enzymes such as SOD , CAT and APX in the root tips of Xai mai 1 and Yangmai 5 are increased significantly under aluminum stress , but the former is significantly higher than that of the latter .
The activity of superoxide dismutase ( SOD ) , CAT ( CAT ) and APX ( APX ) decreased significantly after exogenous o - phen treatment , but no significant change was found in Yangmai 5 .

【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S512.1

【参考文献】