Effects of Exogenous Salicylic Acid Derivative on the Resistance to TMV and Activity of Defense Enzymes of Tobacco

[Objective] This study aimed to evaluate the effects of exogenous salicylic acid derivatives on tobacco resistance to TMV and activity of defense enzymes. [Method] The tobboco leaves were treated by exogenous salicylic acid derivatives. Then, the disease occurrence was observed, and the activity of phenylalanin ammo- nia lyase （PAL） and peroxidase （POX） were measured. [Result] Exogenous salicylic acid derivative increased the activities of PAL and POX, while did not influence the resistance to TMV. [Conclusion] The result provides a theoretical basis for the study of plant disease resistance mechanisms.

Effect of plant extracts on activity of some defense enzymes of apple fruit in interaction with Botrytis cinerea

The efficacy of seven plant extracts(neem,fennel,lavender,thyme,pennyroyal,salvia and asafetida) in controlling postharvest of apple(caused by Botrytis cinerea) was evaluated in vitro and in vivo.In vitro,all plant extracts treatments inhibited spore germination.Inhibitory rates of pore germination was 17.41 and 20.83% for neem extract treatment(methanolic and aqueous extracts,respectively) with significant difference compared to control(73.6 and 85.33%) for aqueous and methanol extracts.In the storage conditions,the application of aqueous extract of neem(at concentration of 25%) resulted in 89.11% reduction of disease severity compared with the untreated control.Results of enzymes activity showed the plant extracts can increase the activity of peroxidase,phenylalanine ammonia-lyase,β-1,3-glucanase and polyphenol oxidase in the presence of pathogens,in apple fruits.However,the results of this research revealed that application of neem extracts was more effective than the application of other plant extracts.According to this study,it could be concluded that plant extracts may be useful to control postharvest disease as a safe alternative option to chemical fungicides.

Effects of Spores and Crude Toxins of Helminthosporium gramineum Rabenh f.sp.echinochloae on the Activity of Defensive Enzymes in Barnyardgrass

[Objective] This study aimed to explore the effects of spores and crude toxins of Helminthosporium gramineum Rabenh f. sp. echinochloae（HGE） on the ac- tivity of defensive enzymes of barnyardgrass [Echinochloa crus-galli （L.） Beauv.]. [Method] The effects of spores and crude toxins of HGE, as well as the mixture of spores and crude toxins on the activity of defensive enzymes in barnyardgrass were determined under laboratory conditions. [Result] Spores and crude toxins of HGE had varying degrees of effects on PAL and POD activity, and no obvious effect on SOD activity in barnyardgrass. In addition, spores and toxins had some similar im- pacts on the defensive enzymes in barnyardgrass. [Conclusion] Since toxins have similar effects on the hosts as spores of fungal pathogen do, they can be a substi- tute for the fungal pathogen in studying the partial pathogenic mechanism of this pathogen due to its complexity in pathogenic process.

Novel 18β-glycyrrhetinic acid amide derivatives show dual-acting capabilities for controlling plant bacterial diseases through ROS-mediated antibacterial efficiency and activating plant defense responses

Natural products have long been a crucial source of,or provided inspiration for new agrochemical discovery.Naturally occurring 18β-glycyrrhetinic acid shows broad-spectrum bioactivities and is a potential skeleton for novel drug discovery.To extend the utility of 18β-glycyrrhetinic acid for agricultural uses,a series of novel 18β-glycyrrhetinic acid amide derivatives were prepared and evaluated for their antibacterial potency.Notably,compound 5k showed good antibacterial activity in vitro against Xanthomonas oryzae pv.oryzae(Xoo,EC50=3.64 mg L–1),and excellent protective activity(54.68%)against Xoo in vivo.Compound 5k induced excessive production and accumulation of reactive oxygen species in the tested pathogens,resulting in damaging the bacterial cell envelope.More interestingly,compound 5k could increase the activities of plant defense enzymes including catalase,superoxide dismutase,peroxidase,and phenylalanine ammonia lyase.Taken together,these enjoyable results suggested that designed compounds derived from 18β-glycyrrhetinic acid showed potential for controlling intractable plant bacterial diseases by disturbing the balance of the phytopathogen’s redox system and activating the plant defense system.

Breeding of Brassica napus Cultivar Zhongshuang9 with High-Resistance to Sclerotinia sclerotiorum and Dynamics of Its Important Defense Enzyme Activity

Zhongshuang9, a new semi-winter Brassica napus variety with high resistance to Sclerotinia sclerotiorum and lodging, high-yield, double-low quality and extensive adaptability, was bred by multiple crossing and microspore culture technique. It was registered and released in China in 2002. In regional trial of Hubei Province in China, Zhongshuang9 yielded 2 482. 2 kg ha-1 averagely in 2000 - 2002, 15. 33% higher than the control variety Zhongyou821. Erucic acid, glucosinolates and oil contents of Zhongshuang9 were 0.23%, 22.69 μmol g-1(in meal)and 42%, respectively. In field assessment of resistance to S. Sclerotiorum , the disease incidence and disease index of Zhongshuang9 averaged 13.31 % and 6.47, respectively, which were lower than those of Zhongyou821 by 28% and 36%, respectively. After inoculation of detached leaves with mycelia, the lesion size of Zhongshuang9 was 4. 709 cm2, which was significantly smaller than that of the mid-resistant variety Zhongyou821(5. 933 cm2). The stem lesion length of Zhongshuang9 after match-stick inoculation was 1.275 cm, which was significantly lower than that of Zhongyou821(1.943 cm). The possible mechanism of resistance to S. sclerotiorum was studied through comparing the activities of phenylalanine ammonia lyase(PAL), exo-chitinase, β-1, 3-glucanase, peroxidase(POD)and polyphenoloxidase(PPO)in Zhongshuang9 with those in other resistant, mid-resistant and susceptible cultivars.

Systemic Activation of Defensive Enzymes and Protection in Tobacco Plantlets against <i>Phytophthora nicotianae</i>Induced by Oligosaccharins

Oligosaccharins are potent biomolecules which activate defense responses and resistance in tobacco plants. However, it is not known the systemic behavior of defensive enzymes activated by these elicitors. In this work, the dynamic behavior of key defensive enzymes was evaluated in tobacco plant leaves previously treated through the roots with chitosan polymer (CH), chitosan (COS) and pectic (OGAS) oligosaccharides and Spermine (Sp). All macromolecules tested activated protein levels and defense enzymatic activity in tobacco leaves but with different response dynamics among them and depending on the biochemical variable evaluated. Defense response above control levels were detected since 12 hours after treatments and it consisted in a biphasic behavior with two peaks for PAL (EC 4.3.1.5) and β 1 - 3 glucanase (EC 3.2.1.6) enzymatic activities. The highest enzymatic levels for these enzymes were achieved at 48 hours in plantlets elicited with COS and at 72 hours for those plants treated with chitosan polymer, while the highest POD (EC 1.11.1.6) activity was detected with CH between 48 and 72 hours. These results demonstrated systemic defense activation by oligosaccharins in tobacco whose dynamic of defense response is affected by the kind of oligosaccharins tested. When applying OGAS by foliar spray on tobacco, systemic resistance against Phytoththora nicotianae was induced and plantlets were protected with the low concentration tested by 46% under the bioassays conditions performed. Moreover, enzymatic determinations on roots and leaves previous to plant-pathogen interaction showed increments above 30% of control levels for PAL and POD activities. It means that oligosaccharins activate local and systemic defense responses in plants in the absent of pathogen infection.

Induced defense responses in rice plants against small brown planthopper infestation

The small brown planthopper(SBPH), Laodelphax striatellus Fallén(Homoptera: Delphacidae), is a serious pest of rice(Oryza sativa L.) in China. To understand the mechanisms of rice resistance to SBPH, defense response genes and related defense enzymes were examined in resistant and susceptible rice varieties in response to SBPH infestation. The salicylic acid(SA) synthesis-related genes phenylalanine ammonia-lyase(PAL), NPR1, EDS1 and PAD4 were induced rapidly and to a much higher level in the resistant variety Kasalath than in the susceptible cultivar Wuyujing 3 in response to SBPH infestation. The expression level of PAL in the Kasalath rice at 12 h post-infestation(hpi) increased 7.52-fold compared with the un-infested control, and the expression level in Kasalath was 49.63, 87.18, 57.36 and 75.06 times greater than that in Wuyujing 3 at 24, 36, 48 and 72 hpi, respectively. However, the transcriptional levels of the jasmonic acid(JA) synthesis-related genes LOX and AOS2 in resistant Kasalath were significantly lower than in susceptible Wuyujing 3 at 24, 36, 48 and 72 hpi. The activities of the defense enzymes PAL, peroxidase(POD), and polyphenol oxidase(PPO) increased remarkably in Kasalath in response to SBPH infestation, and were closely correlated with the PAL gene transcript level. Our results indicated that the SA signaling pathway was activated in the resistant Kasalath rice variety in response to SBPH infestation and that the gene PAL played a considerable role in the resistance to SBPH.

Effect of cadmium on the defense response of Pacific oyster Crassostrea gigas to Listonella anguillarum challenge

Heavy metal pollution can affect the immune capability of organisms. We evaluated the effect of cadmium （Cd） on the defense responses of the Pacific oyster Crassostrea gigas to Listonella anguillarum challenge. The activities of several important defensive enzymes, including superoxide dismutase （SOD）, glutathione peroxidase （GPx）, acid phosphatase （ACP）, Na＋, K＋-ATPase in gills and hepatopancreas, and phenoloxidase-like （POL） enzyme in hemolymph were assayed. In addition, the expression levels of several genes, including heat shock protein 90 （IrtSP9~））, metallothionein （MT）, and bactericidal/permeability increasing （BPI） protein were quantified by fluorescent quantitative PCR. The enzyme activities of SOD, ACP, POL, and GPx in hepatopancreas, and the expression of HSP90 were down-regulated, whereas GPx activity in the gill, Na＋, K＋-ATPase activities in both tissues, and MT expression was increased in Cd- exposed oysters post L. anguillarum challenge. However, BPI expression was not significantly altered by co-stress of L. anguillarum infection and cadmium exposure. Our results suggest that cadmium exposure alters the oysters＇ immune responses and energy metabolism following vibrio infection.

Photosynthetic traits and antioxidative defense responses of Pinus yunnanensis after joint attack by bark beetles Tomicus yunnanensis and T.minor

Bark beetles Tomicus yunnanensis and T.minor are two important pests of Pinus yunnanensis and can cause massive death of pine trees.In this study,we examined several traits related to photosynthesis in P.yunnanensis and their relationship with antibiotic defense responses after joint attack by the two bark beetles at the shoot and the trunk stages.When shoots were attacked by the beetles,the abundance of chlorophylls,carotenoids,and the rates of net photosynthesis(Pn)and transpiration(E)decreased in needles,while the levels of superoxide dismutase and malondialdehyde remained unchanged in both needles and phloem.The activity of peroxidases also remained unchanged in needles,but increased in phloem.The activity of catalases increased in both needles and phloem.When trunks were attacked by the bark beetles,chlorophyll abundance,Pn,E,and antioxidative enzyme activities all declined,and the declines were more pronounced than in the attacked shoots.A decrease in protein concentrations was also observed in needles and phloem from the attacked pines.Attack on shoots by the bark beetles suppressed host defense and provided a favorable environment for larval growth and development,resulting in long-term decline of pine growth potential.The results suggest that attacks on trunks by beetles caused more severe damage to host trees than attacks on shoots.

Enhancement of defense responses by <i>Clonostachys rosea</i>against Botrytis <i>cinerea</i>in tomatoes

Clonostachys rosea (C. rosea) is a biocontrol agent that is used to combat and prevent phytopathogenic fungi attacks because of its ability to involve many factors and diverse modes of action. The reactions of C. rosea on the control of gray mold disease in tomato leaves were investigated in this study. To investigate the reactions of C. rosea in inducing resistance to tomato plants, three treatments, including Botrytis cinerea treatment (treatment B), C. rosea treatment (treatment C), C. rosea and B. cinerea treatment (treatment C + B) and water (control), to be applied on tomato leaves were set up. Disease severity was subsequently evaluated and compared with the control. The treatment of tomato leaves with C. rosea (15 μg/ml) significantly reduced the disease index after inoculation and severity of gray mold caused by Botrytis cinerea. The results indicated that the C. rosea treatment stimulated the activity of the defense related enzymes: Peroxidases (POX), lipoxygenases (LOX) and glutathione S-transferases (GST), and the treatment C + B reduced the incidence and severity of the gray mold. Furthermore, C. rosea treatment increased the activity of pathogenesis related proteins PR1. Therefore, our results suggest that C. rosea could enhance the resistance of tomato plants to gray mold through the activation of defense genes and via the enhancement of defense-related enzymatic activities.

复合木霉制剂防治黄连根腐病及其机理研究

为评价复合木霉制剂对黄连根腐病的防治效果,并揭示其防病机理,为黄连根腐病专用微生物农药的研发奠定基础,本试验将深绿木霉Trichoderma atroviride、长枝木霉T.longibrachiatum、钩状木霉T.hamatum、拟康宁木霉T.koningiopsis等4种木霉配制的复合制剂和尖镰孢Fusarium oxysporum以不同的方式分别施用于黄连,统计根腐病发生情况,检测黄连根部防御酶活性,用高通量测序分析根际土壤真菌群落结构。结果表明,复合木霉制剂对尖镰孢导致的根腐病具有明显预防效果;复合木霉制剂和尖镰孢分别接种黄连可提高SOD、POD、CAT、PAL、PPO等防御性酶活性,产生诱导抗性;而它们先后接种黄连可产生强化效应,从另一个途径提高植株抗病性。复合木霉制剂和尖镰孢都会降低真菌的数量、多样性,和某些真菌的相对丰度,而复合木霉制剂的抑菌作用更强烈,尤其能明显抑制尖镰孢、Ilyonectria sp.等病原真菌的生长,且能改善土壤真菌群落结构。木霉和尖镰孢都能在土壤中较长期定殖。可见,复合木霉制剂可以预防尖镰孢导致的黄连根腐病,防病机理包括诱导黄连植株产生抗性,接种后再遭受病原菌侵染产生的强化效应,优化土壤真菌群落结构,抑制土壤中病原菌等,且有效期较长。因此复合木霉制剂具有开发为微生物农药防治黄连根腐病的潜力。

外源水杨酸对黄瓜幼苗灰霉病防御酶活性的影响

为研究水杨酸(SA)对感染灰霉病黄瓜幼苗防御酶活性的影响,采用叶面喷施外源水杨酸(SA),测定SA对感染灰霉病黄瓜幼苗叶片中多酚氧化酶(PPO)、苯丙氨酸解氨酶(PAL)、过氧化氢酶(CAT)、过氧化物酶(POD)和过氧化物歧化酶(SOD)5种防御酶活性的影响。结果表明:不同浓度SA对黄瓜幼苗抗灰霉病均有作用,能显著降低黄瓜幼苗的病情指数,其中以150 mg·L^(-1)的SA处理后的相对防效最高。叶面喷施150 mg·L^(-1)的SA后,随感染天数的增加PPO、PAL、CAT、POD、SOD 5种防御酶的活性均呈现出先上升后下降趋势,感染期间经SA处理后的5种防御酶的活性均高于未处理,其中PAL活性持续性较好。外源水杨酸能通过促进防御酶活性提高黄瓜幼苗抵抗灰霉病的伤害,浓度为150 mg·L^(-1)的SA处理抵抗作用最好。

外源茉莉酸甲酯诱导大麦叶斑病抗性研究

【目的】探讨不同浓度外源茉莉酸甲酯(MeJA)诱导大麦抗叶斑病效应差异及其分子机制,为应用MeJA防治大麦叶斑病提供理论依据。【方法】以‘蒙啤麦3号’大麦品种幼苗为材料,设置不接菌(无菌水处理叶片)、接菌(无菌水处理叶片接种麦根腐平脐蠕孢菌)和接菌+MeJA(0.5,1.0,1.5,2.0,2.5mmol/LMeJA喷施叶片后接菌)3组处理,于三叶期调查叶斑病发病情况,并据此筛选最适MeJA浓度,然后测定不接菌、接菌及接菌+MeJA(最适浓度)下不同处理时间叶片的抗氧化酶、抗病相关酶活性、丙二醛含量、渗透调节物质含量以及相关基因表达水平。【结果】(1)叶面喷施外源MeJA提高了大麦对叶斑病的抗性,1.5mmol/LMeJA处理叶片的病情指数较对照显著降低19.03%,诱导抗性效果最佳;(2)与单独接菌处理相比,1.5mmol/LMeJA处理大麦叶片超氧化物歧化酶、过氧化物酶、过氧化氢酶、几丁质酶和β-1,3-葡聚糖酶活性均显著提高,而其丙二醛、脯氨酸、可溶性糖和可溶性蛋白含量显著降低,同时受MeJA调控转录因子及编码抗病相关酶的基因表达量显著上调。【结论】外源喷施1.5mmol/LMeJA通过调节抗病相关酶活性和渗透调节物质含量,以及调控抗病相关酶基因及茉莉酸信号途径关键转录因子基因表达,进而提高大麦植株的叶斑病抗性。

棘孢木霉PT-29与枯草芽孢杆菌S-16共培养对马铃薯枯萎病的防控作用

马铃薯枯萎病是一种土传真菌病害,可对马铃薯整个生育期造成严重危害,在全国主要马铃薯产区都有不同程度的发生。为减少化学药剂防治马铃薯枯萎病带来的弊端,提高生防菌剂效果,研究了棘孢木霉(Trichoderma asperellum)PT-29与枯草芽孢杆菌(Bacillus subtilis)S-16对马铃薯枯萎病主要致病菌尖孢镰刀菌(Fusarium oxysporum)的抑菌效果,并通过盆栽试验测定了2株菌共培养发酵液对马铃薯枯萎病的防治效果及对马铃薯相关防御酶活性的影响。结果表明,2株菌单培养和3种比例共培养发酵液对尖孢镰刀菌均有抑制效果且以PT-29与S-16共培养发酵液组合B1T1(比例为1∶1)抑制效果最佳;单培养S-16的发酵液(B)处理对马铃薯枯萎病的防效为60.09%,单培养PT-29的发酵液(T)处理对马铃薯枯萎病的防效为54.85%,B1T1处理对马铃薯枯萎病的防效达到73.44%。此外,B1T1+FO(接种尖孢镰刀菌)处理的马铃薯叶片过氧化氢酶(CAT)、超氧化物歧化酶(SOD)、过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)活性明显高于FO处理,峰值相比于FO处理分别提高56.44%、766.89%、111.84%、179.34%。综上所述,PT-29与S-16共培养发酵液对马铃薯枯萎病的防治效果高于单培养发酵液,为复合微生物防治马铃薯枯萎病提供了理论支持。

光合细菌沼泽红假单胞菌Atp2蛋白对水稻生长及抗逆的影响

【目的】探究光合细菌沼泽红假单胞菌PSB06 Atp2蛋白对水稻生长、防御酶活性及防御相关基因转录水平的影响,为生防菌在水稻上的推广应用提供理论依据。【方法】以水稻品种CO-39为试验材料,用0(蒸馏水,CK)、20和50μg/mL Atp2蛋白3种处理液对水稻种子和叶片进行处理,对生长14d的水稻体内叶绿素a/b和过氧化氢(H_(2)O_(2))含量,以及过氧化物酶(POD)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)、谷胱氨肽还原酶(GR)、苯丙氨酸解氨酶(PAL)、多酚氧化酶(PPO)等水稻防御酶活性进行检测;运用实时荧光定量PCR检测水稻体内防御相关基因(OsWRKY70、OsLOX1、OsAOS2、OsPR1a、OsCHT1和OsPAL1)的转录水平。【结果】与CK相比,Atp2蛋白处理水稻叶片后,其体内叶绿素a/b显著(P<0.05,下同)或极显著(P<0.01,下同)升高,而处理种子后叶绿素a/b无显著变化(P>0.05);Atp2蛋白处理后水稻体内H_(2)O_(2)含量均升高,其中处理叶片后H_(2)O_(2)含量极显著升高;Atp2蛋白处理后水稻体内POD和CAT活性显著或极显著下降;Atp2蛋白处理后水稻体内SOD、GR和PAL活性均极显著升高;Atp2蛋白处理种子后水稻体内PPO活性显著或极显著升高,而处理叶片后PPO活性显著或极显著下降。Atp2蛋白处理后水稻防御相关基因OsWRKY70、OsLOX1、OsAOS2(50μg/mL Atp2蛋白处理水稻叶片外)、OsPR1a和OsCHT1表达均上调,其中OsWRKY70、OsLOX1和OsCHT1基因表达显著或极显著上调;Atp2蛋白处理种子后OsPAL1基因表达极显著上调,而处理叶片后OsPAL1基因表达极显著下调。【结论】沼泽红假单胞菌PSB06 Atp2蛋白对水稻有较好的促生抗逆效果,具有推广应用潜力。

抗辣椒青枯病的糖类筛选及抗性机制研究

【目的】筛选抗辣椒青枯病的糖类,并分析其抗性机制,为辣椒青枯病防治药剂的开发提供理论依据。【方法】以蔗糖、麦芽糖、L-阿拉伯糖、D-乳糖、D-棉子糖、D-果糖、D-半乳糖、D-葡萄糖、D-核糖和D-木糖10种糖为试验材料,供试菌株为假茄科雷尔氏菌(Ralstonia pseudosolanacearum)RS03,分析青枯菌对糖的同化作用,采用幼苗试验和室内盆栽试验筛选对辣椒青枯病防治效果最佳的糖。通过抗菌活性、致病性和趋化性测定分析糖与青枯菌的相互作用;接种青枯菌后第2、4、6和8 d,测定经糖处理的辣椒茎部过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)和多酚氧化酶(PPO)等防御酶活性。【结果】10种糖中,L-阿拉伯糖、D-乳糖和D-棉子糖不被青枯菌同化,选择其进行后续试验;幼苗试验结果表明,L-阿拉伯糖和D-棉子糖均显著降低辣椒青枯病的发病率(P<0.05,下同);室内盆栽试验结果表明,L-阿拉伯糖对辣椒青枯病的防治效果最佳,达90.67%。分析L-阿拉伯糖与青枯菌的相互作用,结果表明,L-阿拉伯糖对青枯菌无抑菌作用且对其致病性没有影响,青枯菌对L-阿拉伯糖无趋化性。防御酶活性检测结果表明,L-阿拉伯糖处理能显著提高辣椒茎部POD、PAL和PPO活性,POD和PPO活性均随着青枯菌接种时间的推移呈增长趋势,在接种8 d后达峰值,分别为571.11和125.33 U/g;而PAL活性呈波动变化趋势,接种后第4 d达峰值,为24.13 U/g。【结论】L-阿拉伯糖对辣椒青枯病的防治效果最佳,其能通过提高植株体内防御酶活性来增强辣椒对青枯病的抗性,具有开发成新型辣椒青枯病防治药剂的潜力。

桃果实采后响应果生链核盘菌侵染的分子机制

褐腐病是采后桃果实最主要的侵染性病害之一,而我国桃褐腐病主要是由链核盘菌属引起,会严重降低果实品质,造成大量损失。为解析桃果实病原菌胁迫响应机制,该文采用分光光度法测定抗病相关酶活性并基于转录组学解析桃果实响应果生链核盘菌的分子机制。结果发现,桃果实的过氧化物酶、苯丙氨酸解氨酶和β-1,3-葡聚糖酶在侵染的不同时期启动了响应反应,参与了桃果实抵御果生链核盘菌侵染过程。基因本体(gene ontology,GO)和京都基因与基因组百科全书(Kyoto Encyclopedia of Genes and Genomes,KEGG)富集分析表明,桃果实对果生链核盘菌的侵染会产生复杂的防御反应。

马铃薯块茎蛾取食诱导的马铃薯防御反应

为探究马铃薯在应答马铃薯块茎蛾Phthorimaea operculella取食时相关抗虫指标的动态变化,本研究以‘青薯9号’‘合作88’‘米拉’3个马铃薯品种为材料进行室内盆栽试验,在马铃薯块茎蛾取食0、3、6、12、24、48、72、96 h时取样测定各品种生理指标。结果表明,被马铃薯块茎蛾取食的叶片中过氧化氢酶、多酚氧化酶、萜烯合成酶活性,单宁和类黄酮含量与对照相比都有不同程度的显著升高,总氨基酸含量显著下降,且各指标在马铃薯品种之间存在差异。从各指标平均增降率来看,‘合作88’对马铃薯块茎蛾取食的响应程度要强于‘青薯9号’和‘米拉’‘米拉’的响应程度最小。本研究为进一步明确马铃薯抗虫生理防御机制和害虫综合防治提供理论依据。

树木伯克霍尔德氏菌DHR18诱导橡胶树抗病性相关防御酶分析

为探究树木伯克霍尔德氏菌(Burkholderia arboris)DHR18诱导橡胶树对胶孢炭疽菌优势种(Colletotrichum siamense)的抗性,以橡胶树苗GT1为材料,检测不同浓度的树木伯克霍尔德氏菌DHR18发酵液处理以及DHR18与胶孢炭疽菌CH-1协同处理下橡胶树叶片中多酚氧化酶(polyphenol oxidase,PPO)、过氧化氢酶(catalase,CAT)、过氧化物酶(peroxidase,POD)、苯丙氨酸解氨酶(phenylalanin ammonialyase,PAL)和超氧化物歧化酶(superoxide dismutase,SOD)5种防御相关酶的活性变化。结果表明:经3个浓度(1×10^(8)、1×10^(7)、1×10^(6) CFU/mL)的DHR18发酵液处理后,橡胶树叶片中CAT、POD、PAL、SOD和PPO活性均高于对照,其中1×107CFU/mL浓度处理的5种防御酶活性最高,防御酶活峰值分别为1 009.14、29 138.67、110.24、902.42、148.00 U/g,分别是对照的2.68倍、3.35倍、1.88倍、3.97倍、4.51倍。树木伯克霍尔德氏菌DHR18与胶孢炭疽菌CH-1协同处理下,先喷施DHR18处理组的5种防御酶活性均高于其他处理组,显著高于对照,其CAT、POD、PAL、SOD和PPO活性峰值分别为1 230.85、45 504.67、117.53、1342.17、134.40 U/g,分别是对照的4.56倍、3.10倍、2.04倍、3.28倍、5.98倍;菌株DHR18对胶孢炭疽菌的平板抑制率为71.56%,在橡胶树苗上对胶孢炭疽病预防效果为81.79%,防治效果为44.35%。研究结果表明,树木伯克霍尔德氏菌DHR18可促使橡胶树防御相关酶的活性提高,诱导橡胶树产生系统抗性,诱导抗病性可能是树木伯克霍尔德氏菌DHR18拮抗胶孢炭疽病的原因之一。

大气CO_(2)浓度升高和温升对水稻纹枯病侵染后的相关蛋白和防御酶的影响

纹枯病(sheath blight)作为一种土传病害,其发生和发展严重威胁到水稻(Oryza sativa L.)的生产。目前,大气CO_(2)浓度([CO_(2)])和温度升高如何影响感病植株内病程相关蛋白(pathogenesis related proteins,PR蛋白)和防御酶尚不清楚。本研究以纹枯病易感品种(Lemont)和抗性品种(YSBR1)为实验材料,利用田间开放式自由大气[CO_(2)]和温度升高(T-FACE)平台设置四个处理:对照、[CO_(2)]升高([CO_(2)]升高至590μmol·mol^(-1))、温升(冠层温度升高2℃)及[CO_(2)]升高和温升交互,通过人工接种Rhizoctonia.solani,探究不同抗性品种叶片和茎鞘PR蛋白与防御酶活性,以及土壤基本理化性状的响应。研究结果表明:高[CO_(2)]和温升下耕作土制成的土壤浸提液培养基中R.solani生长速率无显著差异,接种R.solani后病斑发展速率与土壤基本理化性状无关。水稻植株感病后,两个品种叶片和茎鞘中PR蛋白和相关防御酶表现出明显差异,且在高[CO_(2)]和温升条件下,该差异进一步增大。对于茎鞘中的PR蛋白和防御酶,高[CO_(2)]和温升交互处理明显增加Lemont和YSBR1茎鞘中过氧化氢酶(CAT)、苯丙氨酸解氨酶(PAL)、β-1,3-葡聚糖酶(GLU)和超氧化物歧化酶(SOD)活性。对于两个水稻品种,当R.solani入侵后,在各处理下,YSBR1叶片中PR蛋白和相关防御酶以及茎鞘中SOD和CAT活性均显著高于Lemont,且YSBR1病斑发展速率显著低于Lemont。在整个发病过程中,温升处理及其与高[CO_(2)]互作处理均显著增加易感品种Lemont的病斑发展速率(增加了21%~45%),而对抗性品种YSBR1的病斑发展速率无显著影响。相关性分析结果表明,各处理下Lemont和YSBR1植株纹枯病病斑的发展速率均与其茎鞘中GLU活性存在显著正相关。因而,在R.solani侵染后,抗病品种中较高的PR蛋白和防御酶活性形成的防卫反应,能够有效减轻未来高[CO_(2)]和温升条件对纹枯病病斑发展速度的影响。研究结果对选育纹枯病抗性品种来适应未来气候变化背景下的水稻生产提供重要的借鉴意义。