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.     

Expression of phenolics and defence-related enzymes in relation to red root rot disease of tea plants

Red root rot caused by Poria hypolateritia is a dreadful disease in tea plant due to sudden death of bushes. In response to fungal pathogen, variation in the defence-related enzymes was investigated. The infected tea root was undertaken to study about various defence-related and pathogen-related enzymes. The infected root, as a prime response to disease attack, was subjected to the analysis of phenolics, phenylalanine ammonia lyase, tyrosine ammonia lyase, peroxidase, polyphenol oxidase, catalase, chitinase, β-1,3-glucanase and protease were assayed. The results on assay of defence-related enzymes revealed that the activity was significantly higher in infected roots when compared with healthy roots. Phenolics were accumulated more in infected roots. The sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis further confirmed the presence of induced pathogenesis-related proteins in the infected root tissues. The activity of all enzymes was increased up to threefold amount when compared with normal ones. The accumulation of defence enzymes in plants revealed the virulence of root pathogen in stimulating induced systemic resistance of tea plants and phytopathogenicity causing pathogenesis. This study exemplify to recognise underlying processes in causing infection and to identify the existence of host–pathogen relationship.     

低温与GA_3诱导菠萝黑心病的生理机制

菠萝黑心病是PPO催化氧化酚类物质形成褐色产物所致。低温或GA_3处理提高了PPO活性及其底物——儿茶酚、绿原酸和咖啡酸的含量,也导致了PAL活性增加;低温还使乙烯释放率增大。这些变化均有利于黑心病的发生和发展。     

Activity profile of defence-related enzymes in rice genotypes (Oryza sativa L.) against rice blast (Magnaporthe oryzae)

The control and infected leaf samples of blast resistant and susceptible rice genotypes were evaluated for activities of defence-related enzymes viz., total phenol content, chitinase, phenylalanine ammonia lyase (PAL), β-glycosidase, antioxidative enzymes, superoxide dismutase, peroxidase and ascorbate peroxidase. The level of total phenol content and the activity profile of chitinase, PAL and β-glycosidase significantly increased in both blast-resistant and susceptible rice genotypes with comparatively higher level induction Tetep, NLR-20104 and Swarnadhan the blast-resistant genotypes. The antioxidative enzymes were comparatively higher in the leaf samples of blast-resistant genotypes recording highest increase in NLR-20104 and KJT-5. The constitutive levels of total phenols and activity of defence-related and antioxidative enzymes in the control leaf samples differed among the genotypes and were even higher in the two blast susceptible genotypes (EK-70 and Chimansal). However, the level of induction as evident from the activity profile differences between control and infected leaf samples suggests higher level of induction was more which is indicative of the induced defence response. The genotype recording maximum induction of defence-related and antioxidative enzymes activity could be useful criteria in screening for blast resistant genotype in rice.     

Application of ozone on induction of resistance in Vigna unguiculata cv. Co 6, against Fusarium wilt

Abstract

The efficacy of ozone in controlling Fusarium oxysporum, the casual agent of wilt disease, was evaluated in Vigna unguiculata (cowpea). Different concentrations of ozone (T₁, T₂, T₃, T₄ and T₅) were passed to the Vigna unguiculata seedlings among which T₃ treatment reduced Fusarium wilt more effectively than other treatments by enhancing growth promotion along with the activation of the defense-related enzymes than other treatments. T₃ treatment provokes enhanced biomass production along with increased activity of chitinase, β-1,3-glucanase, peroxidase and phenylalanine ammonia-lyase than other treatments relative to control seedlings. Moreover, this is the first report of ozone protecting seedlings against Fusarium wilt of Vigna unguiculata plants.     

Effect of chitin hexamer and thuricin 17 on lignification-related and antioxidative enzymes in Soybean Plants

Inducers of disease resistance in crop plants have a role in sustainable agriculture. We describe a set of bacteriocins that can potentially improve plant growth by controlling specific pathogens and inducing generalized resistance. Solutions of the bacteriocin thuricin 17 and/or a chitin hexamer (a known inducer and positive control) were applied to leaves of two-week-old soybean plants, and levels of lignification-related and antioxidative enzymes were monitored. Phenyl ammonia lyase (PAL) activity in thuricin 17-treated leaves was highest at 60 h after treatment, being 61.8% greater than the control. PAL activity also was increased 18.1% at 72 h after treatment with the chitin hexamer. Tyrosine ammonia lyase (TAL) activity in leaves was 57.0% higher than the control at 48 h after treatment with thuricin 17, while such activity in chitin hexamer-treated leaves was increased by 23.8% at 72 h. At 36 h after treatment with the chitin hexamer or chitin hexamer + thuricin 17, the total concentration of phenolic compounds was 15.3 or 19.3%, respectively, greater than the control. At 72 h, total phenolic concentrations increased by 23.2 and 19%, respectively, in response to thuricin 17 and chitin hexamer + thuricin 17. POD activity in thuricin 17-treated leaves increased by 74.6 and 81.2% at 48 and 72 h, respectively, whereas SOD activity increased by 24.9 and 79.9%, respectively, in chitin hexamer- and thuricin 17-treated leaves at 48 h. A peroxidase isozyme (31 kDa isomer) was induced in thuricin 17-treated leaves at 60 h, while catalase (59 kDa isomer) was induced in chitin hexamer-treated leaves. PAGE showed that two major SOD bands (Fe-SODs) were produced by both types of treatment. Collectively, these results indicate that the bacteriocin thuricin 17 can act as an inducer of plant disease defenses (i.e., activated lignification-related enzymes, antioxidative enzymes, and related isozymes) and that this induction is similar, but not identical, to that of the chitin hexamer elicitor. Although treatment with thuricin 17 + chitin hexamer also induced those responses, it did not present a clear pattern of additivity or synergy.     

南美斑潜蝇为害对黄瓜体内4种防御酶活性的影响

植物对昆虫取食产生的防御反应,在昆虫与植物相互作用关系中起着重要的作用。为明确南美斑潜蝇Liriomyza huidobrensis(Blanchard)取食与植物防御之间的作用关系,本文分别测定了南美斑潜蝇幼虫持续为害1、3、5、7及9d后黄瓜叶片中苯丙氨酸解氨酶(PAL)、多酚氧化酶(PPO)、过氧化物酶(POD)及超氧化物歧化酶(SOD)活性的变化。结果表明：在南美斑潜蝇幼虫持续取食下,PAL、PPO、POD和SOD等4种酶活性显著上升;PAL、PPO和POD等3种酶活性随受害程度的加重而上升幅度加大,即重度受害>轻度受害>系统对照>健康对照,而SOD活性变化没有规律。在系统对照黄瓜叶片中,PAL、PPO、POD和SOD等4种酶活性最大值分别在第5、1、5和5d;在轻度受害黄瓜叶片中,PAL、PPO、POD和SOD等4种酶活性最大值分别在第5、9、5和9d;在重度受害黄瓜叶片中,PAL、PPO、POD和SOD等4种酶活性最大值分别在第7、7、5和5d。黄瓜叶片受害后,POD和PPO活性上升幅度较大,PAL和SOD活性上升幅度较小,说明POD和PPO对取食胁迫响应比PAL和SOD更灵敏。     

Rhizobacterial-mediated induction of defense enzymes to enhance the resistance of turmeric (Curcuma longa L) to Pythium aphanidermatum causing rhizome rot

Rhizobacteria isolated from the rhizosphere soil were evaluated for their ability to control rhizome rot in turmeric (Curcuma longa L). These isolates were characterised as Pseudomonas fluorescens and Bacillus subtilis. Under in vitro condition, two isolates, namely P. chlororaphis (PcPA23) and B. subtilis (BsCBE4), showed maximum inhibition of mycelial growth of Pythium aphanidermatum, were found effective in reducing rhizome rot of turmeric both under greenhouse and field conditions and increased the plant growth and rhizome yield. Both the isolates were further tested for its ability to induce production of defense-related enzymes and chemicals in plants. Increased activities of phenylalanine ammonia lyase, peroxidase, polyphenol oxidase, chitinase and β-1,3-glucanase were observed in PcPA23 and BsCBE4 pre-treated turmeric plants challenged with P. aphanidermatum. Moreover, higher accumulation of phenolics was noticed in plants pre-treated with PcPA23 and BsCBE4 challenged with P. aphanidermatum. Thus, the present study shows that in addition to direct antagonism and plant growth promotion, induction of defense-related enzymes involved in the phenyl propanoid pathway collectively contributed to enhance resistance against invasion of Pythium in turmeric.     

Effect of drought on biomass, protein content, lipid peroxidation and antioxidant enzymes in two sesame cultivars

The effects of drought on growth, protein content, lipid peroxidation, superoxide dismutase (SOD), peroxidase (POX), catalase (CAT) and polyphenol oxidase (PPO) were studied in leaves and roots of Sesamum indicum L. cvs. Darab 14 and Yekta. Four weeks after sowing, plants were grown under soil moisture corresponding to 100, 75, 50 and 25 % field capacity for next four weeks. Fresh and dry masses, and total protein content in leaves and roots decreased obviously under drought. However, several new proteins appeared and content of some proteins was affected. Measurement of malondialdehyde content in leaves and roots showed that lipid peroxidation was lower in Yekta than in Darab 14. Severe stress increased SOD, POX, CAT and PPO activities in leaves and roots, especially in Yekta. According to the present study Yekta is more resistant to drought than Darab 14.     

A chromium-tolerant plant growing in Cr-contaminated land

In this paper, a kind of Typhaceae plant species, Typha angustifolia L, with a high tolerance to Cr is described. Experiments were carried out to examine its ability to tolerant Cr and its physiological response. The results showed that there was no difference in growth, plant height, and biomass response to external Cr (VI) between the plants exposed to 100 microM Cr (VI) and control (0 microM), while increasing Cr levels to 200-800 microM induced a significant decrease in plant height and biomass, but no significant injury was detected, even for the plants exposed to 800 microM Cr. Chromium induced significant increases in superoxide dismutase (SOD) and peroxidase (POD) activities. Meanwhile, a significantly positive correlation was found between Cr and Mn or Cu in leaves and roots, respectively. The Cr tolerance of the plant appeared to be associated with the enhancement of SOD and POD activities and the improvement in uptake and translocation of the essential microelements.     

锌胁迫对小球藻抗氧化酶和类金属硫蛋白的影响

通过对抗氧化酶活性和类金属硫蛋白的测定,考察在0、5、10、20、50和100 μmol/L Zn²⁺(氯化锌)胁迫下锌对普通海洋小球藻的生物学影响。结果表明:不同浓度Zn²⁺均能抑制小球藻的生长,当Zn²⁺浓度大于10 μmol/L时,小球藻生物量随培养时间延长而迅速下降;过氧化物歧化酶 (SOD)活性随Zn²⁺胁迫浓度的增加而增加,当Zn²⁺浓度为50 μmol/L时SOD活性达到最大,但继续增加Zn²⁺胁迫浓度反而导致SOD活性下降;而过氧化物酶 (POD)活性则随着Zn²⁺胁迫浓度的增加而降低。同时,实验发现藻细胞内有两种主要的锌结合形态,其中Zn结合类金属硫蛋白(Zn-MT-like)与兔肝金属硫蛋白(MT)的分子量相近,且随着Zn²⁺胁迫浓度的增加而出现规律性地增多。因此,藻细胞内Zn-MT-like蛋白的诱导量可作为小球藻受Zn²⁺胁迫的响应指标。     

酵母菌中SOD复合酶的初步研究

对不同酵母菌中ＳＯＤ等抗氧化酶的活性进行了初步的分析测定,筛选出了一株诸酶活性都较高的菌株（丹宝利面包活性干酵母）。研究了该酵母在不同培养时期ＳＯＤ等酶少力的变化情况,发现ＰＯＤ、ＣＡＴ等酶的活性水平ＳＯＤ活性的变化有密切的相关性。通过比较几种提取方法的效果,认为利用甲苯破壁法提取ＳＯＤ复合酶具有一定的可行性。     

高浓度氮、磷胁迫对伊乐藻SOD、POD和CAT活性的影响

以伊乐藻枝条为材料,研究了氮、磷浓度对伊乐藻抗氧化酶系统的影响。结果表明高浓度的氮、磷明显影响伊乐藻枝条的生长,表现为不定根形成减少、生物量增加缓慢、叶绿素含量下降。另外,高浓度的氮、磷还导致伊乐藻过氧化物酶的活性持续升高、而过氧化氢酶和超氧化物歧化酶的活性震荡幅度明显变小,同时细胞内丙二醛含量明显升高。说明伊乐藻抗氧化酶系统的活性受到了干扰,活性氧清除能力下降,氧化胁迫加剧,细胞膜脂过氧化程度增加。这种变化可能是过高氮、磷浓度影响植物生长的内在生理因素之一。     

不同番木瓜品种植株感染环斑花叶病毒后PAL、PPO、POD活性的变化

对不同品种番木瓜接种环斑花叶病毒后,测定植株苯丙氨酸解氨酶(PAL)、多酚氧化酶(PPO)、过氧化物酶(POD)的活性变化,比较各品种的抗病性。结果表明,未接种的5个品种间PAL、PPO、POD活性差异较小,其酶活性水平次序为马来10号> 蜜红3号> 马来6号> 马来2号> 台农2号。接种后,5个品种的PAL、PPO、POD活性明显高于各对照水平,其中马来10号变化最突出,台农2号变化最缓慢。     

脱氧核糖核酸对机体内超氧化物岐化酶和过氧化物酶活性影响初步研究

超氧化物岐化酶（SOD）和过氧化物酶（POD）是机体内重要的抗氧化酶系之一,其作用在于消除体内的自由基,防止自由基对细胞结构的损伤。它们的活性随增龄而下降,因此自由基不断损伤细胞结构,累积最终导致细胞衰亡和动物机体衰老,老龄小鼠服用DNA一段时间后,其体内SOD和POD的活性均显著提高,因而其衰老速度可能得到一定程度的延缓。     

Positive effects of temperature and growth conditions on enzymatic and antioxidant status in lettuce plants

The contents of two bioactive compounds (polyphenols and flavonoids) and their antioxidant and enzyme activities were determined in the leaves of six lettuce (Latuca sativa L.) cultivars subjected to 4 different day/night temperatures for 6 weeks.The total polyphenol and anthocyanin contents and the corresponding antioxidant activities were the highest at 13/10 °C and 20/13 °C, followed by 25/20 °C and 30/25 °C. The enzymatic activities of polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL) were also the highest at low day/night temperatures, but the peroxidase (POD) activity was decreased at low day/night temperatures and increased at high day/night temperatures.The most significant positive correlation existed between anthocyanin content and PPO activity, total polyphenols and their antioxidant activities. The results showed that at relatively low temperatures, lettuce plants have a high antioxidant and enzymatic status. These results provide additional information for the lettuce growers.     

Plant growth regulator interactions results enhancement of antioxidant enzymes in Catharanthus roseus

Abstract

The present investigation was carried out with the objectives to understand the effect of paclobutrazol, gibberellic acid and Pseudomonas fluorescens on the enzymatic antioxidants like Ascorbate peroxidase (APX, EC: 1.11.1.11), Superoxide dismutase (SOD, EC: 1.15.1.1), Catalase (CAT, EC: 1.11.1.6), Peroxidase (POX, EC 1.11.1.7) and polyphenol oxidase (PPO, Ec 1.10.3.1) activities of Catharanthus roseus plants under field conditions. 10 mg l^?1 paclobutrazol, 5 µM gibberellic acid and 1 mg P. fluorescens concentrations were used for the treatments, and control plants were irrigated with well water. The treatments were given 38, 53, 68 and 83 days after planting (DAP) by soil drenching. The plants were taken randomly 45, 60, 75 and 90 DAP and separated into root, stem, leaves and flowers and used for estimating the antioxidant enzymes. The results showed that these plant growth regulators have significant effects on antioxidant enzymes of C. roseus.     

淹水对转超氧化物歧化酶或过氧化物酶基因烟草某些生理生化指标的影响

对盆栽十二叶龄的3个烟草近等基因系进行淹水处理后的结果表明:随着淹水时间的延长,细胞质膜透性、超氧化物歧化酶(SOD)和过氧化物酶(POD)活性均显著升高;叶绿素和可溶性蛋白质含量、株高、叶片数及生物量均下降.各种指标在短时间内不能恢复到正常水平或者根本不能恢复.3个品系抗涝性强弱依序为:转基因抗坏血酸过氧化物酶(APX)高表达品系＞转Mn-SOD基因叶绿体高表达品系＞非转基因品系.     

Wound-induced ethylene production, phenolic metabolism and susceptibility to russet spotting in iceberg lettuce

Mechanical wounding by cuts or punctures caused a brief increase in ethylene production by iceberg lettuce ( Lactuca sativa L.) leaf tissue. Wounding increased phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) activity, which was a function of the degree of injury. Wound-induced PAL activity appeared after 4 h and reached maximum activity in about 24 h before slowly declining to normal levels in about a week. A signal for PAL induction was transmitted at about 0.5 cm h⁻¹ from the site of injury to cells up to 2.5 cm away. Treatment with 100 μ2-aminoethoxyvinylglycine prevented wound-induced ethylene production but did not affect induced PAL activity. Injury increased the concentration of several soluble phenolic compounds that were easily oxidized to brown substances by polyphenol oxidase (EC 1.10.3.2) isolated from lettuce tissue. Wounding also increased peroxidase (EC 1.11.1.7) activity and lignin content, with cell wall lignification localized in wounded and adjacent cells. Although wounding alone did not induce russet spotting, it did greatly increase susceptibility to ethylene-induced russet spot development. In the presence of 3 μ1⁻¹ ethylene, the russet spot score increased as the degree of injury increased.