采前低温诱发菠萝果实黑心病

采前低温可诱发菠萝果实黑心病,发病率变化范围为６０％－１００％,低于２１℃的采前低温影响是诱发菠萝黑心病的重要因子之一。在华南菠萝生产区,不同品种对黑心病敏感性的峭同。因此,培育和栽培抗黑心病的菠萝新品种,将是一个控制黑心病腐烂的重要措施。     

采用GA3诱导菠萝多酚氧化酶活性升高的机理

在多酚氧化酶（ＰＰＯ）提取过程中,直接加入ＧＡ３溶液,不能使ＰＰＯ活性增加。采后ＧＡ３诱导菠萝ＰＰＯ活性升高的同时,显著提高了酸性酸酯酶的活性,这是果实组织的Ｐｉ浓度明显升高的主要原因。随着果实的后熟,磷脂磷Ｄ活性不断下降,ＧＡ３处理显著延缓了该酶的下降速度。虽然采用ＡＢＡ处理使果实ＰＰＯ活性有小幅度增加,但ＡＢＡ处理能使ＧＡ３对ＰＰＯ活性的诱导明显加强。     

采前低温诱发菠萝果实黑心病

采前低温可诱发菠萝果实黑心病,发病率变化范围为60%~100%。低于21℃的采前低温影响是诱发菠萝黑心病的重要因子之一。在华南菠萝生产区,不同品种对黑心病敏感性的表现不同。因此,培育和栽培抗黑心病的菠萝新品种,将是一个控制黑心病腐烂的重要措施。     

红冬孢酵母苯丙氨酸解氨酶基因pal在大肠杆菌中的克隆与表达

以红冬孢酵母总RNA为模板反转录获得其苯丙氨酸解氨酶基因pal,测序与已公布蛋白序列进行比对,相似度为99％.并以含有T7强启动子的pET - 28a(+)为载体构建重组质粒pET - 28a(+)- pal,通过异丙基硫代-β-D-半乳糖苷(IPTG)诱导实现苯丙氨酸解氨酶(PAL)在大肠杆菌中的表达.对诱导条件进行初步优化后,重组茵PAL比酶活可达到42.99 U/g.转化实验中肉桂酸的转化率为48.52％,L-苯丙氨酸生成量为1.73 g/L.结果表明,红冬孢酵母pal基因通过表达载体pET - 28a(+)在E.coli中获得了高效表达.     

低温打蜡对贮藏菠萝黑心病控制的作用

研究了常温、低温、低温加打蜡 3种贮藏条件下菠萝果实硬度、可溶性固形物 (TSS)、可溶性糖醛酸、多聚半乳糖醛酸酶 (PG)和多酚氧化酶 (PPO)等因素的变化 ,及它们对黑心病发生及发展情况的影响。结果表明 ,低温加打蜡可以延缓果肉硬度、可溶性固形物和可溶性糖醛酸含量的下降 ,降低 PG和 PPO的活性 ,降低黑心病的发病率 ,较好的保持果实品质     

采后GA_3诱导菠萝多酚氧化酶活性升高的机理

在多酚氧化酶（ＰＰＯ）提取过程中,直接加入ＧＡ３溶液,不能使ＰＰＯ活性增加。采后ＧＡ３诱导菠萝（Ａｎａｎａｓｃｏｍｏｓｕｓ（Ｌ．）Ｍｅｒ．）ＰＰＯ活性升高的同时,显著提高了酸性磷酸酯酶的活性,这是果实组织的Ｐｉ浓度明显升高的主要原因。随着果实的后熟,磷脂酶Ｄ活性不断下降,ＧＡ３处理显著延缓了该酶的下降速度。虽然采后ＡＢＡ处理使果实ＰＰＯ活性有小幅度增加,但ＡＢＡ处理能使ＧＡ３对ＰＰＯ活性的诱导明显加强。     

奉节脐橙果实苯丙氨酸解氨酶活性及其基因表达与果皮褐变的关系

柑橘果皮褐变严重影响果实的商品价值和耐贮性．以奉节脐橙（Citrus sinensis Osbcck）果实为材料,通过采后常温、涂蜡、低温、机械损伤等处理研究了果实果皮褐变率、苯丙氨酸解氨酶（PAL）活性及PAL上基因在果皮褐变过程中表达水平的变化。结果表明,涂蜡、损伤处理均极显著地提高果实的果皮褐变率,而低温贮藏可显著降低其发生率;贮藏期问各处理的PAL活性均呈上升趋势,损伤处理PAL活性显著高于对照。果实发生褐变或受到机械损伤后,PAL2、PAL6基因的表达均比对照明显增强。结果首次表明脐橙果实PAL活性变化以及PAL2基因的表达与果皮褐变具有非常密切的关系．     

毛头鬼伞多糖对烟草酶活性和同工酶谱的影响

分析了毛头鬼伞(Coprinus comatus)真菌多糖诱导烟草对烟草花叶病毒(TMV)抗性过氧化物酶(POD)、多酚氧化酶(PPO)、苯丙氨酸解氨酶(PAL)、几丁质酶、-β1,3-葡聚糖酶活性的变化。结果表明,毛头鬼伞多糖可提高POD、PPO、PAL、几丁质酶和-β1,3-葡聚糖酶的活性,接种TMV后毛头鬼伞多糖处理的烟草酶活性显著高于不处理者。上述结果提示,毛头鬼伞多糖处理后烟草酶活性的增强可能与其诱导烟草获得抗性有关。     

竹笋采后木质化与多酚氧化酶，过氧化物酶和苯丙氨酸解氨酶活性的关系（简报）

竹笋采后10d内,PPO,POD和PAL活性呈迅速上升趋势,之后缓慢下降,木质素含量在采后10d内迅速增加,随后缓慢增加,1℃和10℃之间的PPO,POD和PAL活性的差异都达显著水平（P＜0．05）,木质素含量的差异达极显著水平（P＜0．01）。     

Azoxystrobin induces lignification-related enzymes and phenolics in rice (Oryza sativa L.) against blast pathogen (Pyricularia grisea)

Abstract

This study was conducted to analyse the induction of lignification-related enzymes and phenolic content in rice to blast disease caused by Pyricularia grisea using azoxystrobin. The severity of rice blast was reduced (70% over control) through treatment by azoxystrobin. This reduction in disease severity was mainly associated with induction of host defense mechanisms by azoxystrobin. Increased production of secondary metabolite – phenolic and lignification – related enzymes, namely, peroxidase (POD), polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL) were observed in rice plants treated with azoxystrobin.     

Changes in defence-related enzymes in rice responding to challenges by Rhizoctonia solani

Sheath blight disease caused by Rhizoctonia solani Kuhn is becoming a major constraint to rice production, especially in the intensified cultivation system. To know the in rice, it is important to get the knowledge of the activity of defence-related enzymes due to the fungal infection. The pathogen induced superoxide dismutase (SOD) and chitinase activities in rice plants, while suppressing peroxidase (POD) and phenylalanine ammonia-lyase (PAL) activities at 36 and 24 h after inoculation, respectively. Induction of two POD isozymes, POD-3 and -4, up to 48 h after inoculation and disappearance of the said isomers at 72 h onwards in rice–Rhizoctonia interaction implicated the role of these isomers in susceptible host–pathogen interaction. Apart from POD and SOD, the activities of other stress-related enzymes, viz. PAL, polyphenol oxidase (PPO) and β-1,3-glucanase were also studied. From this study, it was found that these defence-related enzymes are most significantly related to host–pathogenic interaction.     

Thidiazuron对苜蓿愈伤组织的乙烯生成及其体细胞胚胎发生的影响

苜蓿叶柄在Ｂ５Ｈ培养基上诱导并继代所形成的是无色、松软的胚性愈伤组织,内含许多有分生能力的细胞团。当Ｂ５Ｈ中的ＫＴ用ＴＤＺ替换时,愈伤组织变绿变硬,出现管状分子和芽原基的分化,其体胚发生能力丧失,而且其乙烯生成和ＰＡＬ活性升高。乙烯形成酶的抑制剂ＣｏＣｌ２可以抑制ＴＤＺ的上述作用,部分地恢复愈伤组织的体胚发生能力。ＴＤＺ对愈伤组织的这些作用可能与其促进乙烯生成有关。     

Mechanism of the Increase of Polyphenol Oxidase Activity in Pineapple Fruit Induced by GA3

No increase in polyphenol oxidase (PPO) activity was found by addition of GA3 solution in the enzyme extraction. But acid phosphatase activity was found to be increased in pineapple fruit (Armnas comosus (L.) Merr. ) treated with GA3, which was mainly caused by the significant increase in inorganic phosphate (Pi) content. Phospholipase D activities decreased gradually during the period of fruit ripening but GA3 treatment slowed down these processes. On the other hand, the increase of PPO activities in fruit treated with GA3 was enhanced by the addition of ABA treatment.     

Control of root-knot nematode (Meloidogyne javanica) with combination of Arthrobotrys oligospora and salicylic acid and study of some plant defense responses

Root-knot nematodes (RKN) (Meloidogyne spp.) are economically the most important pathogens of agricultural products. The aim of the present study was to control Meloidogyne javanica by using Arthrobotrys oligospora and salicylic acid (SA) and to analyse the kinetics of enzymes, phenylalanine ammonia lyase (PAL), peroxidase (POX), polyphenol oxidase (PPO) and phenolic compounds accumulation in the root system of tomato after inoculation with M. javanica, A. oligospora and SA. The ability of A. oligospora to produce extracellular proteases was also examined. In greenhouse studies, we used soil drenching of A. oligospora (10⁶ spores/ml) and soil drenching or leaf spraying of SA (5 mM) in six-leaf stage, separately and in combination. Experiments were performed in a completely randomised design. The efficiencies of treatments were appraised by using diameter of galls, number of galls per plant, number of egg masses per plant, number of eggs per egg mass, root and foliage fresh weight. The results showed that the combined application of A. oligospora and SA provided the best nematode control. The activity of the enzymes and phenolic compounds increased in comparison with the control. The nematophagous fungus A. oligospora produced extracellular proteases in the broth culture. Using A. oligospora and SA could be effective in control of M. javanica in tomato.     

棉铃虫持续取食对棉花三种防御酶活性的作用

昆虫取食作为一种关键的生物胁迫因子对棉花防御机制产生了重要影响。植物对昆虫取食产生的防御响应,在昆虫与植物的生态关系中具有重要作用。为了明确棉铃虫Helicoverpa armigera取食与棉花防御性之间的动态互作关系,本文研究了棉铃虫持续取食下及停止取食后,棉花中3种防御相关酶活性变化的时间效应。在明确了棉花受损程度与棉铃虫取食时间关系的基础上,分别考察了棉铃虫持续取食2、6、12、18和24h,对棉花中苯丙氨酸解氨酶(PAL)、脂氧合酶(LOX)和多酚氧化酶(PPO)活性的影响。针对棉铃虫持续取食棉叶12h后停止取食,研究了去除虫害胁迫后0、6、12、24和36h,棉花体内PAL、LOX、PPO活性的变化。结果表明:在棉铃虫持续取食棉叶24h内,棉花中3种防御酶的活性响应有所不同,其中,棉铃虫持续取食2和6h对棉花体内PAL活性没有产生显著影响,而持续取食12h显著诱导了PAL活性,持续取食24和36h,均极显著诱导了PAL活性;棉铃虫持续取食2、6、12、和18h均显著诱导了棉花体内LOX活性,持续取食24h极显著诱导了LOX活性;棉铃虫持续取食6h极显著诱导了棉花体内PPO活性,持续取食24h显著诱导了PPO活性。棉铃虫取食12h后停止取食,在去除虫害除胁迫后0、6、12、24和36h,棉花体内PAL活性均显著升高;而LOX活性则呈现出先升高后恢复正常的现象;PPO活性开始无变化,但在胁迫去除后12和24h显著增高,到36h恢复正常。可见,棉花体内PAL、LOX和PPO活性对棉铃虫取食产生的防御响应,与其受虫害持续取食胁迫时间的增长呈正相关,随着取食时间和受危害的程度加大而升高。并且,在虫害胁迫去除后的一定时间内,棉花体内PAL、LOX和PPO活性依然会保持较高的活性状态,而同等程度机械损伤后的棉叶内PAL、LOX、PPO活性均没有发生显著性变化。说明棉花对于棉铃虫取食胁迫的防御与棉花生理生化性质的改变有关,且具有持续性。     

Inhibition of Biosynthesis of Polyisoprenol Sugars in Chick Embryo Microsomes by Tunicamycin

Changes in the phytoalexin content in unripe fruit of banana, Musa acuminata, were analyzed after various treatments. The results show that level of hydroxyanigorufone started to increase 1-2 day after either wounding or inoculation with conidia of Colletotrichum musae. Inoculation followed by wounding induced the formation of many other phenylphenalenones. The accumulation of hydroxyanigorufone decreased, after its transient maximum, on ripening by exposure of the wounded fruit to ethylene. The level of production of hydroxyanigorufone in ripe fruit treated by wounding and/or by inoculation was much lower than that in unripe fruit. 2-Aminooxyacetic acid, an inhibitor of phenylalanine ammonia-lyase (PAL), inhibited the accumulation of hydroxyanigorufone in wounded fruit, and the PAL activity increased after wounding and ethylene treatment, respectively. Feeding experiments with [1-¹³C] and [2-¹³C]cinnamic acids, and [2-¹³C]malonate show that two molecules of cinnamic acid and one of malonate were incorporated into each molecule of hydroxyanigorufone. The phytoalexins isolated from fruit to which deuterated hydroxyanigorufone and irenolone had been administered revealed that 2-(4′-hydroxyphenyl)-1,8-naphthalic anhydride was biosynthesized from hydroxyanigorufone rather than from irenolone.     

苯丙氨酸解氨酶在诱导黄瓜幼苗抗寒性中的作用

为了探讨苯丙氨酸解氨酶(PAL)在诱导黄瓜幼苗抗寒性中的作用,采用喷施特异抑制剂(AOPP)的方法控制PAL活性,测定幼苗抗寒性的变化.结果表明： 低温可以诱导黄瓜幼苗叶片中PAL的基因表达和活性升高;喷施AOPP显著抑制了叶片中PAL活性,减少了酚类和类黄酮物质的积累.低温对黄瓜幼苗造成显著伤害,AOPP预处理加剧了低温对幼苗的损伤,幼苗抗寒性降低.与对照相比,幼苗叶片中相对电解质渗漏率和丙二醛(MDA)含量显著升高,PSII最大光化学效率(F_v/F_m)降低,光化学猝灭参数Y(NO)升高,胁迫相关基因(PR1-1a、COR47、P5CS、HSP70)的诱导表达受到抑制.低温导致黄瓜幼苗叶片中H₂O₂积累,还原型抗坏血酸(AsA)含量降低,脱氢抗坏血酸(DHA)含量升高,AsA∶DHA减小;喷施AOPP的幼苗中抗氧化酶(过氧化氢酶CAT、抗坏血酸过氧化物酶APX)活性显著低于对照,H₂O₂过量积累,AsA∶DHA更低.施用H₂O₂清除剂可以有效缓解喷施AOPP引起的低温损伤加剧,而施用CAT抑制剂的幼苗对低温胁迫更敏感.表明低温诱导了PAL活性升高,促进了苯丙烷类次生代谢产物的合成,提高了胞内抗氧化酶活性,可有效清除活性氧分子,维持AsA氧化还原状态,缓解低温引起的光损伤和氧化损伤.