甘薯抗蔓割病的酚类物质代谢的研究

通过对甘薯抗蔓割病品种"金山57"和感病品种"岩薯8-6"接菌处理,研究了甘薯体内酚类物质的代谢规律以及与PAL酶活性的变化关系及其对甘薯抗蔓割病的影响。结果表明,两品种接种蔓割病菌后植株体内总酚、类黄酮、木质素、绿原酸、阿魏酸等含量都有提高,但抗病品种比感病品种酚类物质的积累速度快、保持较高浓度的时间长,从而更有利于抵抗病原菌侵染。同时,接菌后PAL酶活性的提高也与品种抗性呈正相关。     

黄瓜枯萎菌粗毒素对不同抗性黄瓜种子萌发及幼苗胁迫作用研究

利用黄瓜枯萎菌粗毒素处理不同抗性品种黄瓜,研究粗毒素对黄瓜种子萌发及幼苗生长的影响,结果表明:粗毒素对不同抗性的黄瓜胚根生长和侧根分化均有抑制作用,且随处理浓度增加,抑制作用愈加明显,但粗毒素对感病品种的抑制作用强于抗病品种。粗毒素胁迫使黄瓜胚根的细胞膜透性、MDA含量、可溶性糖含量增加,其中感病品种的细胞膜透性和MDA含量高于抗病品种,但可溶性糖含量低于抗病品种。在粗毒素处理36 h内,抗感品种黄瓜幼苗的PAL、PPO和POD酶活性均呈现先升高后降低的趋势,其中PAL和PPO的峰值出现在粗毒素处理12 h,而POD的峰值出现在粗毒素处理24 h,抗病品种的3种酶活性峰值高于感病品种。表明抗病品种对黄瓜枯萎菌粗毒素胁迫的抵抗能力强于感病品种。     

硅酸钠对裸仁美洲南瓜酚类物质含量的影响与抗白粉病的关系

以裸仁美洲南瓜抗、 感病品种为材料,测定了硅酸钠溶液喷雾处理南瓜幼苗后诱导接种白粉菌对不同抗病品种裸仁美洲南瓜叶片中酚类物质、 绿原酸、 类黄酮3种物质在不同处理时期含量变化的影响。结果表明,硅酸钠诱导处理后不同抗性品种南瓜叶片中的酚类物质、 绿原酸、 类黄酮等物质含量均明显升高,抗病品种中酚类物质含量在第5 d、 7 d、 9 d时分别高于对照和接菌处理的,绿原酸含量在各个处理时间均高于对照和接菌处理的,类黄酮含量在第7 d、 9 d时分别高于对照和接菌处理的; 感病品种中酚类物质含量和绿原酸含量分别在第5 d、 7 d和9 d时高于对照和接菌处理; 类黄酮含量在第3 d、 5 d、 7 d和9 d时均高于其他处理; 硅酸钠诱导处理后,大多数情况下抗病品种的酚类物质（除第7 d外）、 绿原酸（除第7 d、 9 d外）、 类黄酮等含量均高于感病品种,差异显著,且在接种后第10 d和第15 d白粉病病情指数明显下降。     

甘薯抗疮痂病多胺与吲哚乙酸代谢的研究

研究不同抗性甘薯品种受疮痂病菌侵染前后多胺和吲哚乙酸代谢变化结果表明 ,感染疮痂病菌后抗病与感病品种甘薯叶片中吲哚乙酸含量和多胺氧化酶活性降低 ,多胺总量及腐胺含量增加 ,腐胺 / (精胺 亚精胺 )比值升高 ,感病品种变化幅度高于抗病品种。疮痂病菌侵入后感病品种甘薯叶片中绿原酸含量下降 ,吲哚乙酸氧化酶和过氧化物酶活性升高 ,而抗病品种则相反。     

氯化钾对玉米茎腐病抗性反应中酚类物质代谢的影响

采用田间试验,比较人工接种禾谷镰刀菌（Fusarium graminearum）后,不同氯化钾处理对玉米酚类物质代谢的影响,揭示氯化钾提高作物抗病过程中的酚类物质代谢机理。结果表明,诱导接菌加速了玉米对K+的吸收,且施用氯化钾可以提高接菌后玉米茎髓中苯丙氨酸解氨酶（PAL）的诱导活性,加速多酚氧化酶（PPO）活性的升高,提高过氧化物酶（POD）活性的峰值。此外,施钾还有利于增加茎髓中固有木质素的含量,增加诱导产生的木质素和总酚的积累量。说明钾素可以通过调节酚类物质的代谢,增强次生代谢能力,提高玉米对茎腐病的抗性。     

不同抗性豌豆品种人工接种白粉病后相关生理指标研究

为研究不同抗性豌豆品种在接种白粉菌后相关防御系统酶活性、叶绿素质量浓度的变化,以8个不同抗性豌豆品种为试材,分析了豌豆白粉菌接种后不同时间相关SOD活性、POD活性、CAT活性、叶绿素质量浓度的变化规律。结果表明,接种后SOD活性随着时间变化均表现为先升高后降低,抗病品种的SOD的活性高于感病品种。接种后POD活性随着时间变化呈现持续上升趋势,抗病品种上升幅度高于感病品种。接种后CAT活性随着接种后时间的变化,多数品种呈现先升高后降低的变化。接种后所有品种的叶绿素质量浓度均下降,抗病品种的下降趋势小于感病品种。SOD活性、POD活性变化与品种间差异显著,POD活性、叶绿素质量浓度与豌豆品种的抗性呈正相关。     

青枯菌侵染对烟草叶片H202代谢、叶绿素荧光参数的影响及其与抗病性的关系

对青枯病菌抗性的不同2个烟草品种接种青枯菌后,随接种时间的延长,病株叶片中过氧化氢(H2O2)、超氧物阴离子自由基(O2)、丙二醛(MDA)累积明显高于健株,感病品种"红花大金元"累积幅度大于抗病品种"岩烟97",抗病、感病品种间差异达到显著、极显著水平;病菌感染初期叶片超氧物歧化酶(SOD)活性下降,随后升高,抗病品种活性高于感病品种;过氧化氢酶(CAT)活性先上升而后下降,感病品种降幅高于抗病品种;过氧化物酶(POD)活性先下降而后上升,感病品种升幅大于抗病品种;病株叶绿素可变荧光(Fv)、光系统Ⅱ原初光能转换效率(Fv/Fm)及光系统Ⅱ的潜在活性(Fv/Fo)均受到抑制,感病品种受抑制程度大于抗病品种,这表明烟草品种对青枯菌的抗性与H2O2代谢以及叶绿素荧光参数有着密切关系.     

湿度对甘薯愈伤的影响

为探索湿度对甘薯愈伤的影响,本试验以普薯32号甘薯为原料,人工模拟机械损伤后于25℃、不同相对湿度(RH50%和RH80%)条件下愈伤,通过比较甘薯木质素生成、失重率、呼吸强度、愈伤过程关键酶活性、总酚和类黄酮含量的差异,评价湿度对甘薯愈伤的影响。结果表明,RH80%条件下较RH50%更有利于甘薯愈伤木栓组织的形成,在愈伤4 d时甘薯木质素积累达到最高。与RH50%组相比,RH80%条件处理能显著提高甘薯愈伤组织苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)和多酚氧化酶(PPO)活性(P<0.05),提升总酚、类黄酮含量,促进呼吸高峰提前,降低甘薯重量损失。相关性分析表明,RH80%条件下愈伤,甘薯木质素含量与PAL、POD、PPO活性及总酚、类黄酮含量呈显著正相关(P<0.05)。本研究结果为甘薯采后愈伤提供了一定的理论依据。     

施硅对感染白粉病小麦叶片抗病相关酶活性及硅微域分布的影响

以抗/感白粉病的南农99-18/苏麦3号为试验材料,研究外源硅对接种白粉病后小麦叶片的几丁质酶、β-1,3葡聚糖酶、苯丙氨酸解氨酶(PAL)、多酚氧化酶(PPO)活性和叶片硅微域分布的影响,以探讨外源硅增强小麦抗白粉病的作用机理。结果表明,在不接病原菌时,施硅与否对抗/感病品种的PAL、PPO、β-1,3葡聚糖酶活性和感病品种的几丁质酶活性无显著性影响,但施硅可显著地提高抗病品种的几丁质酶活性;接种病原菌后,抗/感品种小麦叶片的几丁质酶、β-1,3葡聚糖酶、PAL和PPO活性均显著提高,而施硅处理显著地提高了感病品种的这四种酶活性和抗病品种的几丁质酶与β-1,3葡聚糖酶活性,但施硅处理对于抗病品种的PAL和PPO活性影响不显著。同时,施硅处理下,叶片硅元素相对重量都有不同程度提高,并有向刺状体基部和维管束组织富集趋势;接种病原菌后,叶片硅元素明显向病原菌侵染位点聚集,尤其有外源硅供给条件下,这种富集效应尤为显著。这意味着,硅不仅通过调节植株体内与抗病性密切相关的酶活性,而且同时可通过在侵染位点的淀积而构建了防病原菌侵入的"物理或机械屏障",以达到增强小麦的抗病性,从而抑制小麦白粉病病害发展。     

气调贮藏对竹笋内源激素及木质化相关酶活性的影响

研究了MA贮藏对采后竹笋内源激素含量及木质化相关酶活性的影响.结果表明竹笋贮藏期间,GA3和IAA含量逐渐减少,ABA含量先增加后减少,苯丙氨酸解氨酶(PAL)、肉桂酸-4-羟化酶(C4H)和过氧化物酶(POD)活性先增加后减少,木质素含量和组织硬度逐渐增加,而可食用率则逐渐下降.MA贮藏能延缓内源GA3和IAA含量的降低,并抑制PAL、C4H和POD活性的上升,降低竹笋的木质素含量和硬度.MA贮藏抑制竹笋木质化可能与提高内源激素(GA3、IAA)含量和降低PAL、C4H及POD活性有关.     

植物防御酶与桉树对焦枯病抗性的关系

为筛选鉴定桉树对焦枯病(CylindrocladiumqulnqueSeptatumMorgan)抗性的生化指标,对福建省11个桉树主栽种系接种焦枯病菌前后关键防御酶系中的过氧化物酶(POD)和超氧岐化酶(SOD)活性及其同工酶变化进行了研究.结果表明:无论是桉树健叶还是接种后的病叶,体内POD、SOD活性均表现为抗病种系>中抗种系>中感种系>感病种系,呈规律性变化;接种前后POD同工酶谱带数与桉树对焦枯病的抗性间不呈规律性变化,而SOD谱带数与抗病性成正比.从抗病育种角度出发可将接种前后桉树POD、SOD活性和接种后SOD同工酶谱带作为桉树对焦枯病抗性早期鉴定的生化指标.     

Phenolic compounds and related enzymes are not rate-limiting in browning development of fresh-cut potatoes

The effect of minimal processing on polyphenol oxidase (PPO), peroxidase (POD), phenylalanine ammonia-lyase (PAL), and phenolic compounds was studied in five potato cultivars (Agria, Cara, Liseta, Monalisa, and Spunta). Minimal processing caused an overall increase in PPO, POD, and PAL activities. The isoform pattern of PPO was the same for all of the cultivars before and after processing. No latent PPO was detected. The isoperoxidase pattern was approximately the same among cultivars. An increase in POD activity was related to the specific induction of an acidic isoperoxidase. PAL showed an induction pattern characterized by the presence of a maximum peak of activity after 4 days of processing for all of the cultivars. The sequence of browning susceptibility of potato cultivars was as follows: Monalisa > Spunta > Liseta > Cara > Agria. Browning development was only partially correlated to PAL activity (only during the first 4 days after wounding). However, this correlation could not explain the above sequence of browning susceptibility. Minimal processing caused an increase of chlorogenic acid, whereas tyrosine content remained unchanged. In summary, no significant correlation was found between either rate or degree of browning and any other biochemical and physiological attribute investigated (PPO, POD, hydrogen peroxide, ascorbic acid content, and initial phenolics content as well as total and individual phenolics accumulation).     

Stimulation of phenolic metabolism by silicon contributes to rice resistance to sheath blight

Sheath blight caused by Rhizoctonia solani is a major disease of rice worldwide. Silicon (Si) can enhance rice resistance to sheath blight, but the relation with phenolic metabolism is poorly known. Two rice cultivars with different levels of resistance to R. solani (resistant Teqing and susceptible Ningjing 1) were studied to determine the effects of Si on disease intensity (rated from 0 to 9) and the involvement of phenolic compounds in disease resistance. Variation in the concentrations of phenolics (including total soluble phenolics, flavonoids, and lignin) and in the activities of defense‐related enzymes polyphenoloxidase (PPO) and phenylalanine ammonia‐lyase (PAL) in rice leaf sheaths was investigated. The results show that Si application reduced sheath‐blight disease ratings of Ningjing 1 and Teqing by 2.96 and 0.65, respectively. In uninoculated plants, Si application alone had no significant effects on the concentrations of phenolic compounds or on the activities of PPO and PAL. In inoculated plants, Si application increased phenolics concentrations and PPO and PAL activities only in the susceptible cultivar Ningjing 1. We conclude that Si‐induced enhancement of phenolic metabolism contributed to the improved resistance of rice to sheath blight in the sensitive cultivar.     

甘薯长喙壳侵染对甘薯块根抗氧化酶活性的影响

以易感黑斑病甘薯品种“徐薯18”为试验材料, 分别接种分离自石榴、甘薯和芋头的甘薯长喙壳(Ceratocystis fimbriata), 研究其保护酶活性及丙二醛(MDA)含量变化。结果显示, 非亲和性菌株[分离自石榴的甘薯长喙壳(CQS2)和分离自芋头的甘薯长喙壳(YP1)]和亲和性菌株[分离自甘薯的甘薯长喙壳(SP1)]接种的甘薯块根苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性, 与对照处理相比均有升高, 且接种CQS2 和YP1 的处理始终高于接种SP1 的处理; 非亲和性菌株和亲和性菌株接种的甘薯块根MDA 含量均呈先上升后下降趋势, 且接种CQS2 和YP1 的处理在接种25 h 时MDA 含量明显高于接种SP1 的处理, 接种SP1 的处理在接种后期(50 h)的MDA 含量降至与对照相当水平。由此表明: 不同寄主的甘薯长喙壳侵染甘薯块根后, 非亲和性接种菌株(CQS2 和YP1)比亲和性接种菌株(SP1)能增强POD、SOD和CAT 酶活性及诱导较多的MDA, 从而增强病原菌侵染的抗性。     

Effect of wounding on phenolic enzymes in six minimally processed lettuce cultivars upon storage

The effect of wounding on polyphenol oxidase (PPO), peroxidase (POD), and phenylalanine ammonia-lyase (PAL) was studied in six minimally processed lettuce (Lactuca sativa L.) cultivars upon storage for 7 days at 5 degrees C (Iceberg Mikonos (IM), I. Green Queen (IGQ), I. Asdrúbal (IA), Little Gem Sandra (LGS), Romaine Cazorla (RC), and R. Modelo (RM)). Wounding of lettuce tissue midribs (because of minimal processing) caused an exponential increase in PPO activity due to the activation process from latent to fully active PPO by following first order kinetics in the time range from 3.7 days (LGS) to 6.3 days (RC). However, total PPO activity (active plus latent) remained constant. Isoform pattern of PPO changed upon storage probably because of posttranslational processes. POD activity linearly increased with induction of new POD isoenzymes. PAL activity presented a typical bell-shaped induction pattern in four cultivars. Only IM and IGQ showed a second induction response which has not been previously described in the literature. IM was the cultivar most susceptible to browning and RC was the cultivar least susceptible. However, no clear correlation was observed between browning and any of the biochemical and physiological attributes investigated (PPO, PAL, and POD activities, total and individual phenols accumulation, and ascorbic acid content).     

Biochemical study of leaf browning in minimally processed leaves of lettuce (Lactuca sativa L. var. acephala)

A series of biochemical parameters, including the concentration of total ascorbic acid (ASA(tot)) and the activities of phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), and peroxidases (PODs), was investigated during cold storage (72 h at 4 degrees C in the dark) in fresh-cut (minimally processed) leaves of two lettuce (Lactuca sativa L. var. acephala) cultivars differing in the susceptibility to tissue browning: Green Salade Bowl (GSB), susceptible, and Red Salade Bowl (RSB), resistant. The two cultivars showed differences also at the biochemical level. The content in ASA(tot) increased in RSB, as a consequence of increased DHA concentration; conversely, ASA(tot) diminished in GSB, in which ASA was not detectable after 72 h of storage, thus suggesting a disappearance of ascorbate (both ASA and DHA) into nonactive forms. The antioxidant capacity (as determined by using FRAP analysis) decreased significantly during storage in RSB, while a strong increase was observed in GSB. PAL activity increased soon after processing reaching a maximum by 3 h, then it declined to a relatively constant value in RSB, while in GSB it showed a tendency to decrease in the first few hours from harvest and processing. POD activity, at least for chlorogenic acid, increased significantly during storage only in GSB.