The reactive oxygen species network pathways: an essential prerequisite for perception of pathogen attack and the acquired disease resistance in plants

Availability of complete Arabidopsis(Arabidopsis thaliana) and rice(Oryza sativa) genome sequences, together with molecular recourses of functional genomics and proteomics have revolutionized our understanding of reactive oxygen species (ROS) signalling network mediating disease resistance in plants. So far, ROS have been associated with aging, cellular and molecular alteration in animal and plant cells. Recently, concluding evidences suggest that ROS network is essential to induce disease resistance and even to mediate resistance to multiple stresses in plants. ROS are obligatory by-products emerging as a result of normal metabolic reactions. They have the potential to be both beneficial and harmful to cellular metabolism. Their dual effects on metabolic reactions are dosage specific. In this review we focus our attention on cellular ROS level to trigger beneficial effects on plant cells responding to pathogen attack. By exploring the research related contributions coupled with data of targeted gene disruption, and RNA interference approaches, we show here that ROS are ubiquitous molecules of redox-pathways that play a crucial role in plant defence mechanism. The molecular prerequisites of ROS network to activate plant defence system in response to pathogen infections are here underlined. Bioinformatic tools are now available to scientists for high throughput analysis of cellular metabolisms. These tools are used to illustrate crucial ROS-related genes that are involved in the defence mechanism of plants. The review describes also the emerging findings of ROS network pathways to modulate multiple stress resistance in plants.     

Map-based cloning of the tomato genomic region that spans the Sw-5 tospovirus resistance gene in tomato

Two yeast artificial chromosomes (YACs) containing genomic DNA from tomato have been isolated using CT220, an RFLP marker which is tightly linked to the tomato spotted wilt virus resistance gene, Sw-5. High-resolution mapping of the YAC ends and internal YAC probes demonstrated that one of the YAC clones, TY257 (400 kb), spans Sw-5. By chromosome walking in a cosmid library, the position of Sw-5 has been delimited within the YAC to a maximal chromosomal segment of 100 kb, spanned by nine overlapping cosmid clones. Received: 13 March 1997 / Accepted: 11 may 1997     

Peroxidase isoenzymes in the defense response of Capsicum annuum to Phytophthora capsici

Quantitative and qualitative changes in isoperoxidase patterns from stems of three cultivars of pepper ( Capsicum annuum L.). one susceptible, one intermediate and one resistant, were found upon inoculation with Phytophthora capsici using a decapitation method. The peroxidase activity was determined in the intercellular fluid as well as in the cytosolic fraction of the necrotic, healthy and intermediate zones of stems of the three cultivars, 6 days after inoculation. In the intercellular fluid, peroxidase activity of the susceptible cv. Yolo Wonder increased somewhat from 4.7 (healthy zone) to 12.9 (intermediate zone) μmol mg⁻¹ protein min⁻¹, whereas in the intermediate cv. Americano, the peroxidase activity decreased from 123 (healthy zone) to 78 (intermediate zone) μmol mg⁻¹ protein min⁻¹. The most dramatic increase (5.7 to 662 μmol mg⁻¹ protein min⁻¹) in intercellular peroxidase activity was found in the resistant cv. Smith-5. This, in conjunction with the appearance of an additional acidic isoperoxidase (pI 4.4) specific for the cv. Smith-5, could be the reason for the resistance of this cultivar against the fungus attack. The release of peroxidase into the intercellular space as a defense reaction was confirmed by histochemical analysis, showing that peroxidase activity occurred in the intercellular spaces of those stems of the resistant cultivar that had not yet been invaded by the fungus, but was detected neither in the other cultivars nor in the intercellular spaces of such stems of the intermediate and susceptible cultivars that contained growing mycelium of P. capsici. The lack of staining in the intercellular spaces of the susceptible cultivars could be attributed to their low content in peroxidase.     

A revised nomenclature for chitinase genes

The nomenclature for chitinase genes has been revised to correspond to the nomenclature of PR-proteins and to distinguish classes from families. Accordingly, there are now four families of chitinases, two of which are further divided in classes.     

Elicitins与植物的抗病性

Elicitins是一类分子量约为10kD的小分子蛋白激发子,由Phytophthora和Pythium两个属的植物病原卵菌胞外分泌产生,在烟草上引起过敏性反应(hypersensitive response,HR)和系统获得抗病性(systemic acquired resistance,SAR)。中从Elicitins结构与功能、生物学意义、基因表达调控,Elicitins在植物上诱发的信号传导和转Ebcitins基因的抗病基因工程5个方面概述了Elicitins的研究进展。     

利用转基因技术培育抗病虫水稻进展中的问题与对策

近年来,转基因技术在水稻抗病、虫育种的研究得到广泛开展。人们利用转基因手段,已获得一批对病、虫害有一定抗性的水稻植株。并利用这些抗性植株转育得到了一批具有应用潜力的籼、粳稻栽培品系。但要将这些品系真正应用于商品化生产仍有一段距离。针对国内外在这一领域的研究进展作一简单介绍,并就水稻抗虫、抗病分子育种中存在的问题发表一些看法,同时提出解决这些问题的初步思路。     

Effect of benzothiadiazole,an inducer of systemic acquired resistance,on the pathogenesis of wheat brown rust

We studied the effects of systemic acquired resistance inducer, benzothiadiazole (BT, benzo-(1,2,3-thiadiazole-7-carbothionic acid S-methyl ester, commercial name BION), on the development of brown rust caused by the fungus Puccinia triticina Erikss. in nearly isogenic lines of common wheat (Triticum aestivum L, cv. Thatcher) carrying the resistance genes Lr19 and Lr24. A dependence of BT efficiency on the time between treatment with the inducer and inoculation with urediniospores was observed. A difference in BT action on pathogenesis during wheat line infection with virulent and avirulent P. triticina clones was detected. In compatible combinations, the morphogenesis of virulent clone mycelium was suppressed without the hypersensitive response. The inhibition of the development of avirulent clone colonies was accompanied by the intense hypersensitive response. Treatment with cycloheximide enhanced avirulent clone development during 3 days after inoculation; however, later colony growth ceased.     

Antioxidant enzymes as redox-based biomarkers: a brief review

The field of redox proteomics focuses to a large extent on analyzing cysteine oxidation in proteins under different experimental conditions and states of diseases. The identification and localization of oxidized cysteines within the cellular milieu is critical for understanding the redox regulation of proteins under physiological and pathophysiological conditions, and it will in turn provide important information that are potentially useful for the development of novel strategies in the treatment and prevention of diseases associated with oxidative stress. Antioxidant enzymes that catalyze oxidation/reduction processes are able to serve as redox biomarkers in various human diseases, and they are key regulators controlling the redox state of functional proteins. Redox regulators with antioxidant properties related to active mediators, cellular organelles, and the surrounding environments are all connected within a network and are involved in diseases related to redox imbalance including cancer, ischemia/reperfusion injury, neurodegenerative diseases, as well as normal aging. In this review, we will briefly look at the selected aspects of oxidative thiol modification in antioxidant enzymes and thiol oxidation in proteins affected by redox control of antioxidant enzymes and their relation to disease. [BMB Reports 2015; 48(4): 200-208]     

A linkage map of diploid Avena based on RFLP loci and a locus conferring resistance to nine isolates of Puccinia coronata var. ‘avenae’

An F₂ oat population was produced by crossing the diploid (n=7) species Avena strigosa (CI 3815) with A. wiestii (CI 1994), resistant and susceptible, respectively, to 40 isolates of Puccinia coronata, the causal agent of crown rust. Eighty-eight F₂ individuals were used to construct an RFLP linkage map representing the A genome of cultivated hexaploid oat. Two hundred and eight RFLP loci have been placed into 10 linkage groups. This map covers 2416 cM, with an average of 12 cM between RFLP loci. Eighty-eight F₃ lines, derived from F₂ individuals used to construct the map, were screened for resistance to 9 isolates of P. coronata. One locus, Pca, was found to confer a dominant resistance phenotype to isolates 203, 258, 263, 264B, 290, 298, 325A, and 345. Pca also conferred resistance to isolate 276; however, an unlinked second gene may also be involved.Journal Paper No. 15143 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project No. 3134 and 2447     

宠物抗病育种

宠物的抗病育种研究具有重要的意义,本文对开展抗病育种的必要性、宠物免疫抗病系统、疾病抗性遗传机制、免疫反应的遗传控制、宠物抗病常规育种、宠物抗病分子育种以及抗病育种方法的现状、存在的问题、展望进行了介绍。说明了对疾病抗性的选择有一个坚实基础。抗病育种是控制疾病的有效方法,应用前景美好。     

Isolation and linkage mapping of NBS-LRR resistance gene analogs in red raspberry (<Emphasis Type="Italic">Rubus idaeus</Emphasis> L.) and classification among 270 Rosaceae NBS-LRR genes

Plant R genes confer resistance to pathogens in a gene-for-gene mode. Seventy-five putative resistance gene analogs (RGAs) containing conserved domains were cloned from Rubus idaeus L. cv. ‘Latham’ using degenerate primers based on RGAs identified in Rosaceae species. The sequences were compared to 195 RGA sequences identified from five Rosaceae family genera. Multiple sequence alignments showed high similarity at multiple nucleotide-binding site (NBS) motifs with homology to Drosophila Toll and mammalian interleukin-1 receptor (TIR) and non-TIR RNBSA-A motifs. The TIR sequences clustered separately from the non-TIR sequences with a bootstrap value of 76%. There were 11 clusters each of TIR and non-TIR type sequences of multiple genera with bootstrap values of more than 50%, including nine with values of more than 75% and seven of more than 90%. Polymorphic sequence characterized amplified region and cleaved amplified polymorphic sequence markers were developed for nine Rubus RGA sequences with eight placed on a red raspberry genetic linkage map. Phylogenetic analysis indicated four of the mapped sequences share sequence similarity to groupTIR I, while three others were spread in non-TIR groups. Of the 75 Rubus RGA sequences analyzed, members were placed in five TIR groups and six non-TIR groups. These group classifications closely matched those in 12 of 13 studies from which these sequences were derived. The analysis of related DNA sequences within plant families elucidates the evolutionary relationship and process involved in pest resistance development in plants. This information will aid in the understanding of R genes and their proliferation within plant genomes. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

苯并恶唑嗪酮类化合物功能与生物合成研究进展

苯并恶唑嗪酮(benzoxazinoids,BXs)是植物体内一种重要的次生代谢物,因其具有防御作用和化感作用得到了广泛的关注和研究。随着基因组学及分子生物学的发展,苯并恶唑嗪酮的生物合成在分子领域的研究取得了很大的进展。介绍了苯并恶唑嗪酮概况、苯并恶唑嗪酮的功能以及苯并恶唑嗪酮生物合成参与基因及表达调控。     

植物抗病基因克隆的进展

抗病基因是抗病分子生物学和抗病育种的基因,本文介绍了近几年植物抗病基因克隆的进展,抗病基因克隆的新策略以及抗病基因结构特点与抗病机制的研究进展,讨论了抗病基因克隆的应用前景。     

Bifunctional α-amylase/trypsin inhibitor activity previously ascribed to the 22 KDa TL protein, resided in a contaminant protein of 14 KDa

The previously reported inhibitory activity of a 22 KDa protease and α-amylase inhibitor extracted from maize seeds, was re-investigated in order to confirm or rectify its ability to inactivate protease and α-amylase activities. The same inhibition was detected when the 22 KDa protein was purified following the original methodology (Richardson et al. 1987). However, when a new ion-exchange chromatography step was introduced after the RP-HPLC, the apparently homogeneous 22 KDa protein was further resolved into five different fractions. Four of them corresponded to different isoforms of the 22 KDa protein, all of which lacked inhibitory activity. The other small band corresponded to a contaminant protein, which was identified as the 14 KDa α-amylase/trypsin inhibitor. This protein was responsible for the reported double inhibition (protease and α-amylase inhibition), previously assigned to the 22 KDa protein. With this result, it was then possible to settle the question concerning the ability of this 22 KDa protein to inhibit those enzymatic activities. Interestingly, the four isoforms of the 22 KDa protein fractions showed anti-fungal activity when tested in vitro. In summary, we suggest that both the PR-proteins, as well as the inhibitor's family classification, should now be corrected. Thus, the 22 KDa protein should no longer be considered as a member of either the protease or of the amylase inhibitor families. Similarly, the inhibitory activity assigned to the PR-proteins should no longer be considered.     

Elicitation of peroxidase activity and lignin biosynthesis in pepper suspension cells by Phytophthora capsici

Cell suspension cultures of three varieties of Capsicum annuum L., each with a different degree of sensitivity to the fungus Phytophthora capsici, responded to elicitation by both lyophilized mycelium and fungus filtrate with a hypersensitive reaction. They showed the synthesis or accumulation of PR-proteins with peroxidase (EC 1.11.1.7) activity and the accumulation of lignin-like polymer (as measured by derivatization with thioglycolic acid). The cultivation medium was optimised for both plant and fungus growth in order to avoid any stress during their combination. The resistant pepper variety, Smith-5, showed a more intense response to the elicitor preparations than the sensitive varieties, Americano and Yolo Wonder. This was particularly evident when the cell suspensions were elicited with the filtrate. After elicitation, the cell walls thickened through the accumulation of lignin, as can be observed by staining microscope preparations with methylene blue. Elicitation also reduced the level of total peroxidase activity in the susceptible varieties, while such activity increased in resistant varieties, and was accompanied by de novo expression of acidic peroxidase isoenzymes in the extracellular and cell wall fractions. Of note was the PR protein of pI 5.7 showing peroxidase activity, which was induced by both elicitor types in the elicited cell suspensions of the resistant variety alone, making it a marker of resistance. The increases in the activity of these peroxidases in the resistant variety are in concordance with the accumulation of lignin observed 24 h after inoculation by both elicitors from the fungus. The possible role of these isoenzymes in lignin biosynthesis, used to reinforce the cell walls against fungal penetration of the cells, is discussed. These results are in accordance with those previously observed in plant stem sections.     

微生态调节剂对提高中国对虾抗病力的研究

应用从健康中国对虾肠道中分离筛选出的无毒、无害菌群（ＪＸ５、ＪＸ６）制成微生态调节剂,将其作为饲料添加剂饲养中国对虾,对感染暴发性流行病的抗病力进行试验研究。结果表明：（１）微生态调节剂能够明显地提高中国对虾感染后的成活率,使死亡高峰时间延迟;（２）感染后的血液病理指标显示,病虾的血清总蛋白、白蛋白、球蛋白等指标下降,甘油三酯、碱性磷酸酶、乳酸脱氢酶等指标上升;（３）投喂微生态调节剂的试验组与对照组经感染致病后,其血液指标与健康虾比较变化幅度不同,试验组虾血液指标变化幅度小于对照组。本文同时对微生态调节剂抗病力的作用机制进行了初步探讨。