Activation of Defense Responses to Fusarium Infection in Asparagus densiflorus

Defense responses to Fusarium oxysporum f. sp. asparagi and F. proliferatum were compared after root inoculation of the asparagus fern, Asparagus densiflorus vars. Myersii and Sprengeri, and cultivated asparagus, A. officinalis cv. Guelph Millennium. Both varieties of A. densiflorus exhibited a hypersensitive response with rapid death of epidermal cells within 8–24 h and restricted the fungal growth. In A. officinalis roots, rapid cell death was not found, and necrotic lesions were observed 8–14 d after fungal inoculation. Peroxidase and phenylalanine ammonia-lyase activities increased significantly in inoculated A. densiflorus but not A. officinalis plants. Local and systemic induction of peroxidase activity was detected after pathogen inoculation in root and spear tissues, respectively, of A. densiflorus. POX activity decreased in roots of inoculated A. officinalis by 8 d post-inoculation. Germination and germ tube growth were inhibited when spores of F. oxysporum f. sp. asparagi were incubated in root exudates and on root segment surfaces of inoculated A. densiflorus plants exhibiting hypersensitive cell death. Spore germination of F. proliferatum and three fungi non-pathogenic to cultivated asparagus was inhibited as well. Rapid induction of hypersensitive cell death in A. densiflorus was associated with restriction of fungal growth, and activation of peroxidase and phenylalanine ammonia-lyase, two defense enzymes thought to be important for plant disease resistance.     

绿色棉苯丙氨酸解氨酶基因GhPAL1的克隆和实时定量表达分析

本研究以拟南芥(Arabidopsis thaliana)苯丙氨酸解氨酶(PAL)基因cDNA序列(AAC18870.1)为探针,在GenBank中与棉花EST进行tBLASTn比对,将同源性高的EST序列拼接后获得一条棉花PAL全长cDNA基因序列,以此序列为模板设计引物,通过RT-PCR扩增从绿色棉纤维分离出了一个绿色棉PAL基因全长cDNA序列,将该基因命名为GhPAL1(GenBank登录号:JN032297)。序列分析表明,该cDNA全长2347bp,含有一个编码721个氨基酸的开放阅读框。实时荧光定量PCR分析发现:该基因在绿色棉纤维中的表达模式与白色棉纤维相似,但两者在同一时期的表达量差异显著,其在花后6d绿色棉纤维细胞中的表达量是同期白色棉的6倍以上,从该基因的表达特征推测GhPAL1基因可能在绿色棉纤维色素合成过程中发挥重要作用。     

杏树受嗜果刀孢菌侵染后叶片内苯丙氨酸解氨酶活性的变化

初步研究了杏树叶片受嗜果刀孢菌Ｃｌａｓｔｅｒｏｓｐｏｒｉｕｍ　ｃａｒｐｏｐｈｉｌｕｍ（Ｌｅｗ）Ａｄｅｒｈ．侵染后苯丙氨酸解氨酶（ＰＡＬ）活性的变化，结果表明：接种后抗病品种苯丙酸类代谢被激活的程度高。李光杏（高抗）在接种后１２ ｈ与８４ ｈ出现两个酶活性高峰，张公园杏（中抗）在接种后６０ ｈ ＰＡＬ活性达到最高，兰州大接杏（感病）在接种后８４ｈ才趋于活性高峰。供试品种只有李光杏与对照达到差异显著（ａ＝ ０．０１），表明高抗品种酶活性高峰出现得早，升高幅度大。     

黄瓜不同抗病品种感染镰刀菌枯萎病菌后几种酶活性的变化

 镰刀菌枯萎病的侵染使寄主黄瓜根部的苯丙氨酸解氨酶、过氧化物酶和多酚氧化酶活性增加,抗病、感病各品种的3种酶活性曲线均呈现两个峰值,抗病各品种酶活性峰Ⅰ值比感病品种高。其中,感病品种的3种酶活性峰Ⅱ值大于峰Ⅰ值,而抗病品种酶活性峰Ⅰ值、Ⅱ值则在不同酶里有不同变化。在未感染情况下,抗病品种根部的苯丙氨酸解氨酶、过氧化物酶和多酚氧化酶活性比感病品种高。     

树皮内酚类物质的含量及苯丙氨酸解氨酶的活性与杨树抗溃疡病的关系

本文通过不同含水量盆栽苗的接种试验,结果表明,水分亏缺是杨树溃疡病发生发展的诱因。在树皮含水量高的植株中,苯丙氨酸解氨酶(PAL)的活性强,邻苯二酚和对-羟基苯甲酸等酚类物质的含量高,且它们的活性(或含量)随着树皮含水量的降低而降低。室内抑菌试验及盆栽苗的注射试验证明了邻苯二酚是寄主活体内的重要抑菌物质。     

Constitutive expression of a phenylalanine ammonia-lyase gene from Stylosanthes humilis in transgenic tobacco leads to enhanced disease resistance but impaired plant growth

Transgenic tobacco plants expressing a phenylalanine ammonia-lyase cDNA (ShPAL), isolated from Stylosanthes humilis, under the control of the 35S promoter of the cauliflower mosaic virus were produced to test the effect of high level PAL expression on disease resistance. The transgenic plants showed up to eight-fold PAL activity and were slowed in growth and flowering relative to non-transgenic controls which have segregated out the transgene. The expression of the ShPAL transgene and elevated PAL levels were correlated and stably inherited. In T₁ and T₂ tobacco plants with increased PAL activity, lesion expansion was significantly reduced by up to 55% on stems inoculated with the Oomycete pathogen Phytophthora parasitica pv. nicotianae. Lesion area was significantly reduced by up to 50% on leaves inoculated with the fungal pathogen Cercospora nicotianae. This study provides further evidence that PAL has a role in plant defence.     

Fucoidans of Moroccan Brown Seaweed as Elicitors of Natural Defenses in Date Palm Roots

Fucoidans from Moroccan brown seaweed Bifurcaria bifurcata and Fucus spiralis were tested for their elicitor activity after their purification and complete characterization. The fucoidans of B. bifurcata (BBF) and of F. spiralis (FSF) were extracted and purified then characterized by infrared spectroscopy, proton nuclear magnetic resonance spectroscopy and size exclusion chromatography. The results show that BBF and FSF are mainly sulfated with 45.49 and 49.53% (w/w) sulfate, respectively. Analysis of neutral sugars determined by gas chromatography–mass spectrometry showed that FSF and BBF were mainly composed of 64% and 91% fucose and 20% and 6% galactose, respectively, with a few other sugars such as glucose (8% in FSF), rhamnose (1% in BBF) and mannose (8% in FSF and, 2% in BBF). The eliciting activity of these sulfated polysaccharides in stimulating the natural defenses of the date palm was evaluated through the activity of phenylalanine ammonia-lyase (PAL), and the increase in phenols and lignin content in the roots. The results obtained clearly show that the two fucoidans early and intensely stimulate the natural defenses of the date palm after 24 h of treatments. This remarkable elicitor effect seems to be linked to the sulfated groups compared to non-sulfate alginates extracted from the same algae. These results open promising perspectives for a biological control approach against date palm diseases.     

不同年龄杉木抗炭疽病与一些酶活性及同工酶的关系

抗病杉木受炭疽病菌侵染后,其叶组织内多酚氧化酶（PPO）、过氧化物酶（PO）和苯丙氨酸解氨酶（PAL）活性的增加高于中抗和感病的杉木,而中抗杉木又高于感病杉木;抗病杉木受侵染后产生两条新的PPO同工酶谱带和两条新的PO同工酶谱带;中抗杉木产生1条新的PPO同工酶谱带和1条新的PO同工酶谱带;感病杉木只产生一条新的PO同工酶谱带,没有新的PPO同工酶谱带出现。     

甘蓝型黑籽和黄籽油菜种子发育过程中种皮色泽差异研究：Ⅰ．花色素、苯丙氨酸和苯丙氨酸解氨酶的变化及相关性

甘蓝型油菜种皮的花色素，苯丙氨酸解氨酶和苯丙氨酸的动态化研究结果表明，在种子发育过程中，黑籽种皮的花色素含量和苯丙氨酸解氨酶活性高于黄籽，但黄籽种皮的游离苯丙氨酸含量明显高于黑籽，差异达极显著水平。花色素，苯丙氨酸，苯丙氨酸解氨酶三者之间的相关性分析表明，黑籽的花色素含量与苯丙氨酸解氨酶活力呈正相关，与游离苯丙氨酸含量呈负相关，说明油菜黑籽与黄籽种皮的颜色差异与花色素含量有关，花色素可能由游离苯丙氨酸转化而来。     

烟粉虱刺吸诱导转Bt＋CpTI基因棉苯丙氨酸解氨酶和氧保护酶系活性变化

本研究测定并比较了不同时期转双价基因棉SGK321和其亲本常规棉SY321叶片中苯丙氨酸解氨酶（PAL）、过氧化物酶（POD）、超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的总活性。结果发现,烟粉虱取食诱导使棉叶中PAL、POD的活性上升,SOD的活性则是先下降后升高,CAT的活性基本呈下降趋势。SGK321处理植株叶片中PAL活性在不同时期均高于SY321,而POD活性在不同时期均高于SY321;SGK321处理植株上部叶片SOD活性在处理30d前明显高于SY321,40d时低于SY321;SGK321处理植株叶片中CAT活性多数时期低于SY321。最后,探讨了转双价基因棉花与其亲本常规棉对烟粉虱防御反应的差异。