Plant and fungal cells are surrounded by a cell wall rich in diverse polysaccharides and proteins.It has become apparent in recent years that the carbohydrates in the cell wall function not only to maintain cell shape and integrity,but also may serve as signals in plants(Mohnen et al.,1993).Oligogalacturonic acid(OGA),a well studied elicitor,is derived from plant cell walls(Nothnagel et al.,1983).When added to cultured plant cells,it induces an oxidative burst within minutes,releasing ROS via a pathway that involves receptor binding,activation of a G-protein,influx of Ca2+,stimulation of phospholipase C,and induction of a number of kinases(Apostol et al.,1989;Horn et al.,1989;Legendre et al.,1992;Chandra et al.,1995;Legendre et al.,1993).Purified OGAs 13 to at least 26 residues long stimulate pp34 thiophosphorylation in vitro(Philippe et al.,1995).OGAs are also involved in the induction of the jasmonate pathway during plant defense response to E.carotovora subsp.Carotovora attack(Cecilia et al.,1999).The first response observed after the addition of OGAs that is clearly involved in plant defense is the production of active oxygen species,including H2O2,and O2-.This response,termed the oxidative burst,occurs within a few minutes after the addition of OGAs to suspension-cultured soybean,tobacco,and tomato cells.Reactive oxygen species are thought to have direct(through cytotoxicity)and indirect(through signaling)roles in the plant cell death required for the HR.Reactive oxygen species induce the expression of defense related genes,and are implicated as second messengers that elicit other defense responses,including systemic acquired resistance(SAR)and the HR(Brent etal.,2001).Different elicitors are thought to activate different sets of second messengers.The two signaling events that appear to participate in the OGAs inducing plant defense include the oxidative burst and NO accumulation.Inhibitors of mammalian nitric oxide synthase reduced both OGA-induced NO ac-cumulation and NOS activity,suggesting that OGA-induced NO production occurs via a NOS-like enzyme(Hu et al.,2003). Nitric oxide(NO)is a highly reactive molecule that rapidly diffuses and permeates cell membranes.During the last few years NO has a significant role in plant resist-ance to pathogens by triggering resistance-associated cell death and by contributing to the local and systemic induction of defense genes.NO stimulates signal transduction pathways through protein ki-nases,cytosolic Ca2+mobilization and protein modification(María et al.,2004). Most of the ex-perimental data available on NO detection during plant-pathogen interactions come from studies of infections by biotrophic pathogens(María et al.,2004). Additionally,an increase in NOS activity correlated with the pathogen resistance response has been observed in resistant tobacco during TMV infection( Durner et al.,1998;Chandok et al.,2003).Here we report that OGAs induced a range of defense responses in tobacco,including oxidative burst,NO accumulation and stimulation of superoxide dismutase(SOD)activity and catalase(CAT)activity.Furthermore,we show that tobacco plant sprayed with OGAs developed a resistance against infection by tobacco mosaic virus.We also provide evidence that the defense response induced by OGAs was connected with H2O2 and NO pathway.Plants of tobacco(Nicotiana tabacum var.sam sun NN)were grown from seeds in a greenhouse and were used at the 4~6-leaf stage after 2 months in culture.The plants were kept in a growth chamber at(23±1)℃ with a photoperiod of 16 h and 70%~80%relative humidity for several days before treatments.Diphenylene iodonium(DPI),2-(N-morpholino)ethanesulfonic acid(MES),Sodium nitroprusside(SNP),catalase(CAT,from bovine liver),NG-nitro-L-arginine-methyl eater(L-NAME)and 4,5-diaminofluorescein diacetate(DAF-2 DA)were obtained from Sigma.2′,7′-dichlorofluorescin diacetate(H2DCF-DA)from Biotium.All other reagents were from Shanghai Chemical Reagent CO.,LTD,Tianjin Kermel Chemical Development Centre,or Beijing Chemical Plant.OGAs was prepared from enzymatic hydrolysis of pectin and separated with membrane according to the report(H Zhang et al.,1999).An aliquot of OGAs was dissolved in water and analyzed with a matrix-assisted laser desorption-ionization time-of-flight mass spectrometer(MALID-TOF-MS,Bruker,Germany).Tobacco mosaic virus(TMV)that came from our collection was multiplied in N.tabacum.TMV was extracted from systemic infected plants by homogenization of infected leaves in 0.05mol/LH3PO4 buffer(0.05mol/L KH2PO4,0.05 M Na2HPO4 pH 6.8)with subsequent clarification of the extract by centrifugation at 2000g for 6 min.The supernatant extract was used for mechanical inoculation.All leaves of plant were sprayed with 50μg/ml of OGAs,the control plants were sprayed with water.24h~25d after OGAs application,plants were inoculated mechanically with TMV.The lesion caused by TMV was investigated at 7d after inoculation.Results were analyzed using Duncan's multiple range test at P= 0.05.For measurements of SOD and CAT activities,tobacco leaves treated with OGAs were kept in liquid nitrogen.The enzymes in the frozen powders were extracted by adding 0.05g polyvinylpyrrolidone and 5ml 0.05mol/L sodium borate buffer at pH 8.8 and homogenized at 4℃.SOD activities were measured as described by Zhu Guanglian(Zhu Guanglian et al.,1990).CAT activity was determined using the method of Beers&Sizers(Beer et al.,1952).NO and H2O2 measurement was performed using their fluorescent indicator dye DAF-2 DA and H2DCF-DA as described previously by H.Kojima(H.Kojima et al.,1998)with slight modifications.The epidermis was peeled carefully from abaxial surface of the leaves and cut into 5-mm length.Epidermal strips were placed into Tris/KCl buffer(Tris 10 mmol/L and KCl 50mmol/L,pH 7.2)containing DAF-2 DA at a final concentration of 10μmol/L for 30min,or H2DCF-DA at 50μmol/L for 10min,at 26℃ in the dark.The epidermal sections were removed and transferred to a dish of fresh Tris/KCl buffer(without probe)to wash off excess fluorophore apart from light.Then the epidermal strips were placed in Tris/KCl buffer containing OGAs and inhibitors.Examination of peels was performed using laser scanning confocal microscopy(Leica,TCS SP2)with exciting wavelength 488 nm,emitting wavelength 505~530nm.Plants were sprayed with 0.01 and 0.1 mmol/L of sodium nitroprusside(SNP),50μg/ml of OGAs,1 mmol/L,10mmol/L and 100 mmol/L H2O2,H2O2 scavenger catalase(CAT,100unit/ml)and OGAs cotreatment,H2O2 scavenger ascorbic acid(0.1mmol/L)and OGAs cotreatment and NOS inhibitor L-NAME(1mmol/L)for 30min before OGAs respectively.The control plants were sprayed with water.In all cases,24h after OGAs and other materials applications,plants were inoculated with TMV.The lesion caused by TMV was investigated at 7d after inoculation.The effect of OGAs,SNP and H2O2 on local infection was calculated from the ratio of the number of local lesion produced on the treated leaves to that on the control leaves treated with water.The TOF-MS profiles of OGAs sample were showed in Figure 1.The mass spectrum indicated that peaks corresponding to the mass numbers of( M+ Na)+of trimer to enneamer were detected.So the sample was composed mainly of OGAs having degree of polymerization( DP)2-8.Figure 1 TOF-MS of oligochitosan sampleThe results of control effects on TMV with OGAs at different concentration(50～100μg/ml)showed that the best concentration was 50 μg/ml(data not shown).The effects of application of OGAs at different time were summarized in Table 1.It was found that tobacco leaves treated with OGAs were protected against TMV infection.When the inoculation occurred at 19d after spraying 50μg/ml OGAs on tobacco plants,the relative control effect was 53.42%.We concluded that the resistance induced by OGAs became better with the inducing time until 19d.The resistance was reduced after 19d.Dayof50μg/mlgalacturonideappliedNumberoflesioncausedbyTMVRelativecontroleffect(%)vcdsaw1d125±5814.40a?4d116±3920.55a?7d120±4217.81a10d84±3742.47ab13d97±4433.56ab16d90±3238.36ab19d68±3453.42b22d71±3451.37b25d89±3739.04bck146±51—Table 1We examined the effects of OGAs on the activity of plant resistance correlated enzymes.The results(Figure 2 and Figure 3.)indicated that OGAs increased activity of SOD and CAT compared with the H2O-treated ones.There are no distinct differences on the activity of POD and PPO of tobacco leaves treated with OGAs or water(data not shown).SOD and CAT are concerned with eliminating oxygen free radical.Within one hour,activities of CAT and SOD were induced to maximum.Figure 2 Time course of SOD activity in tobacco leaves treated by 50μg/ml OGAs or H2O as CKFigure 3 Time course of CAT activity in tobacco leaves treated by 50μg/ml OGAs or H2O as CKBecause of activity of SOD and CAT induced by OGAs and the two enzymes correlative with oxygen free radical,we examined the production of H2O2 induced by OGAs.To study the effects of OGAs on the production of H2O2 in tobacco cells,the H2O2-sensitive fluorophore H2DCF-DA were used.The results of production of H2O2 in epidermal cells of tobacco leaves induced by OGAs were shown in Figure 4.It was found that OGAs caused an increase of intracellular H2DCF-DA fluorescence in epidermal cells and guard cells of tobacco leaves,indicating the production of H2O2.Fluorescence became visible along the plasma membrane and in organelles in the epidermal cells of tobacco leaves treated with OGAs(Figure 4C),but the fluorescence was very faint in the epidermal cells only loaded with H2DCF-DA(Figure 4A).The Figure 4E and G showed that CAT and DPI could inhibit the level of H2DCF-DA fluorescence in the cells of tobacco leaves treated with OGAs.The results revealed that CAT and DPI could suppress the production of H2O2.Figure 4 Laser scanning confocal microscopy of OGA-induced production of H2O2 in epidermal cells of tobacco leaves. (A) The cells loaded with H2DCF-DA. (B) Bright field image of the cells loaded with H2DCF-DA. (C) The cells loaded with H2DCF-DA before treatment with OGA. (D)Bright field image of the cells loaded with H2DCF-DA before treatment with OGA. (E) The cells loaded with H2DCF-DA and elicited by OGA in the presence of the CAT. (F) Bright field image of the cells loaded with H2DCF-DA and elicited by OGA in the presence of the CAT. (G) The cells loaded with H2DCF-DA and elicited by OGA in the presence of the DPI. (H) Bright field image of the cells loaded with H2DCF-DA and elicited by OGA in the presence of the DPI.The NO-sensitive fluorophore DAF-2DA was used to observe NO accumulation.The observed LSCM results of OGAs-induced production of NO in epidermal cells of tobacco leaves were shown in Figure 5.It was found that OGAs could enhance the level of intracellular DAF-2DA fluorescence in epidermal cells of tobacco leaves,indicating massive production of NO.Production of NO and/or accumulation was observed in organelles and along the plasma membrane in the epidermal cells of tobacco leaves treated with OGAs(Figure 5C).However,the DAF-2DA fluorescence indicating production of NO was not observed in the epidermal cells only loaded with DAF-2DA(Figure 5A).The results also indicated that CPTIO and L-NAME could inhibit the level of H2DCF-DA fluorescence in the cells of tobacco leaves treated with OGAs(Figure 5E and G).The results representedthat CPTIO and L-NAME could suppress the production of NO.Figure 5 Laser scanning confocal microscopy of OGA-induced production of NO in epidermal cells of tobacco leaves. (A) The cells loaded with DAF-2 DA. (B) Bright field image of the cells loaded with DAF-2 DA. (C) The cells loaded with DAF-2 DA before treatment with OGA. (D) Bright field image of the cells loaded with DAF-2 DA before treatment with OGA. (E) The cells loaded with DAF-2DA and elicited by OGA in the presence of the CPTIO. (F) Bright field image of the cells loaded with DAF-2DA and elicited by OGA in the presence of the CPTIO. (G) The cells loaded with DAF-2DA and elicited by OGA in the presence of the L-NAME. (H) Bright field image of the cells loaded with DAF-2DA and elicited by OGA in the presence of the L-NAME.As H2O2 and NO appear to be a key factor associated with plant induced defense disease,it was interesting to test the effect of exogenous NO and H2O2.The effect of OGAs,NO donor SNP and H2O2 at different concentrations and some scavengers are summarized in Figure 6.It was found that treatment with OGAs,SNP and H2O2 protected tobacco leaves against TMV local infection.The least lesion was observed at the treatment of 50μg/ml OGAs among the all treatments.The inhibition effect of H2O2 showed dependence on the amount of H2O2.The lesion of co-treatment of OGAs and the H2O2 scavenger CAT or ascorbic acid on TMV infection was as high as CK.We also observed SNP inducing resistance was dose-dependent.When the tobacco plants were treated with L-NAME before OGAs,the induced resistance was depressed.Therefore,we can presume NO and H2O2 are important factors participating in OGAs inducing resistance to TMV.Figure 6 Effect of OGAs and exogenous NO and H2O2 on disease symptomPectic oligosaccharides,produced by microbial enzymes,are well-known oligosaccharins,eliciting defence responses in diseased plants(Dumville et al.,2000).A broad spectrum of OG-induced pathogenesis-related defense responses has been reported(M.T.Esquerré-Tugayé et al.,2000).Most defense and developmental responses are induced by OGAs with a degree of polymerization(DP)between 10 and 15 galacturonic acid residues.OGAs with a DP less than 8 can also trigger defense responses in plants:they induce accumulation of protease inhibitors(T.Moloshok et al.,1992),ethylene production(S.D.Simpson et al.,1998)and elicitation of genes involved in jasmonic acid metabolism in tomato(C.Norman et al.,1999).In this report,we observed the OGAs with a DP between 2~8 could induce tobacco resistance to TMV.The concentration of OGAs used was also discussed.OGAs-induced plant growth has been reported(LoSchiavo et al.,1991;Filippini et al.,1992),and the maximal effect to growth was about 10-4 M(Stephen et al.,1993).To elicit plant defense responses,OGAs concentration higher than those usually required for control developmental process.In our experiments,50μg/ml was the best concentration to induce resistance within 100μg/ml(data not shown).It showed the efficiency of the OGAs in inhibition of virus infection was not depended on the dose of OGAs.But the inhibition effect was dependent on the treatment time.We observed the inducing effect of resistance to TMV was gradually elevated before 19d,but the mechanism of this needed further study.Research showed that lag period of the induced resistance of glucohexaose was about 7days and the protection period was about 28 days(Li Hongxia et al.,2005).Furthermore,tobacco plants treated by sulfated fucan or linear β-1,3 glucan showed resistance to TMV or bacterium E.carotovora after 5 days(Olivier Klarzynski et al.,2003;2000).So far no oligosaccharides were reported to have so long time inducing effect.Therefore,OGAs have more predominance to be applied in agriculture.Experimental results also showed that NO and H2O2 played important roles in OGAs inducing tobacco resistance to TMV.NO and H2O2 as important signaling active molecules in pathogen defense reaction has been extensively studied(Levine et al.,1994;Mehdy et al.,1996;Baker et al.,1995;Jabs et al.,1996;Delledonne et al.,1998;Rout-Mayer et al.,1997?;Binet et al.,1998).First,we examine the activity of plant resistance correlated enzymes.Because the activity of PAL has been confirmed elevated by many reports(Messiaen et al.,1994;Lapous et al.,1998;Dixon et al.,1989;Tepper et al.,1990),we just mensurated the PPO,POD,SOD and CAT.This includes the activity of SOD and CAT elevated,so we estimated the extra H2O2 production.To evaluate the stimulatory effect of OGAs on tobacco cells,we measured the production of H2O2 and NO in tobacco cells.The data indicated that OGAs induced the production of H2O2 and NO in epidermal cells of tobacco within a short time.These results were in agreement with the reports by Xiangyang Hu,who claimed OGAs stimulated NO accumulation in the growth medium of ginseng suspension cultures(Hu et al.,2003).Rout-Mayer and Binet discovered respectively H2O2 production within a few minutes after the addition of OGAs to suspension-cultured tobacco cells(Rout-Mayer et al.,1997;Binet et al.,1998).Many reports show H2O2 and NO exist are correlated to plant defense.H2O2 is involved in the induction and/or execution of hypersensitive reaction(C.S.Bestwick et al.,1997).H2O2 is required for the cross-linking of plant cell wall components as a part of the structural defense response(C.Lamb et al.,1997).The production of H2O2 may also lead to the development of an antimicrobial environment within the apoplast(M.Peng et al.,1992).In many cases,H2O2 collaborate with NO to execute invading pathogens.H2O2 and NO production were induced almost at the same time by cryptogein,a fungal elicitor(Foissner et al.,2000).NOS inhibitors compromise the hypersensitive resistance response in Arabidposis and tobacco(Delledonne et al.,1998?;Huang et al.,1998).TMV infection could elevate NOS(nitric oxide synthase)activity,and NO could induce PR-1 expression(Durner et al.,1998).NO,as well as other ROS,have been shown to stimulate the accumulation of SA(Durner et al.,1999),which play a critical signaling role in the activation of plant defense responses after pathogen attack.Furthermore,to test whether OGAs functions on inducing resistance in tobacco via NO and H2O2 pathway,we examined the effects of OGAs,exogenous NO donor SNP and H2O2 on inducing resistance to TMV.It was found that all of these treatments reduced lesion caused by TMV.But co-treatment with OGAs and H2O2 scavenger CAT or ascorbic acid blocked the inducing resistance.The tobacco plants inhibited NOS activity by L-NAME were not induced resistance by OGAs.So the defense response induced by OGAs was connected with NO and H2O2 pathway.The study reported herein reveals that OGAs can induce the production of H2O2 and NO,and induce the defense response against TMV.Our understanding of OGAs induced resistance is sketchy.The mechanisms of OGAs eliciting defense responses of tobacco need further investigation.

产业集群是在某个特定区域内以一个主导产业为核心，大量产业联系密切的企业及相关支撑机构在空间上集聚并形成强劲、持续竞争优势的现象。高新技术产业是由处于时代前沿的先导性技术发展起来的产业。与传统产业相比，高新技术产业是一种具有高技术、高投入、高风险、高附加值特征的产业，知识和技术是其投入要素，技术创新能力的形成是决定其生存和发展的关键。高新技术产业集群是指在高技术领域内具有相互关联的企业和机构在一定的地域内聚集，形成上、中、下游机构完整、外围支持产业体系健全、充满创新活力的有机体系。目前，高新技术产业集群有两种基本形式：与大企业共生的中小企业聚集网络和依靠技术合作与创新形成的企业聚集网络。高新技术产业的国际通行做法是根据R&D（研究开发）投入在总产出中所占比例来界定高新技术产业，科学技术的创新和转化将直接影响着高新技术产业的发展。实践表明，高新技术企业往往以“集聚”的方式集中布局，形成高新技术产业集群。与传统意义上的产业集群相比，高新技术产业集群有许多新的特征。高新技术产业集群中的企业主体以相当数量的技术为依托，以创新为基础，企业间联系以知识、信息为核心。集群中的环境因素有利于技术的创新、传播。技术的创新是高新技术产业最重要的竞争手段，企业集聚就是为了利用区域中的创新资源，提高创新效率。高新技术产业集群的产品附加值高，产业带动性强，可迅速成为区域经济的主导。高新技术产业集群一旦形成，可以带动本地区的经济快速发展。例如中关村科技园区虽然只有20多年的历史，其新增国民生产总值已经占到北京市新增产值的一半，成为北京经济发展的重要支柱。另外，与传统产业集群还有不同的是，新型人力资本因素和区域产品链和产业链的配套能力已经成为决定高新技术产业集群优势高低的主要因素。技术创新的研究经历了一个从“线性范式”到“网络范式”的转变。在熊彼特创新理论的影响下形成了创新研究的“线性范式”。该范式认为技术创新一般经历发明—开发—设计—中试—生产—销售等简单的线性过程，研究局限于单个企业内部的技术过程。后来的研究发现外部的信息交换及协调对于创新具有重要的作用，它可以有效克服单个企业技术创新时的能力局限，降低创新活动中的技术和市场不确定性。此后，创新研究的视野从单个企业内部转向企业与外部环境的联系和互动，导致“网络范式”的兴起。“网络范式”最初应用在国家层面，形成了“国家创新系统”理论。随着全球化的发展，经济意义上的“国家状态”日益让位于“区域状态”，区域成为了真正意义上的经济利益体，关键的商业联系集中于区域范围内。进一步的研究发现创新网络的成效似乎跟创新主体的空间分布有很大的关系，地方化的创新网络似乎比跨国技术联盟更能持久。区域发展理论和国家创新理论构成了区域创新系统理论。当创新系统研究发展到区域创新阶段，已经开始与产业集群的研究结合起来了。产业集群与技术创新的关联性也日益密切。技术创新是企业整合创新资源进行创新的过程，技术创新资源包括专业化人才、资金、信息、公共服务等等，其中，专业化人才是企业技术创新活动中最重要的创新资源。在高新技术产业集群内，一方面，有为企业提供人才供给的大学、科研机构、培训机构等；另一方面，高新技术产业集群本身对人才的强烈吸纳能力造成大量人才慕名而来，也形成专业化人才的供给。高新技术产业集群内激烈的竞争为企业技术创新提供了动力。竞争是企业进行技术创新的基本推动力，而竞争会随着市场上参与企业个数的增多而加剧。在产业集群的相对狭窄的地理范围内通常聚集着几十家甚至上百家企业并进行着同类或相似产品的生产，集群内的竞争非常激烈。由于集群内的企业之间在资金、技术等方面的竞争优势差异很小，从而迫使企业必须通过不断地技术创新来获取竞争优势。不管是走低成本路线还是走产品差异化路线，企业都必须通过技术创新来确立自己的独特地位。因此，迫于生存压力，集群内的企业与集群外的企业相比，更具有实施技术创新的动机。另一方面，在集群内，企业进行创新的可见度较高，创新者的领先效益和示范效应突出，率先进行技术创新的企业所取得的超额垄断利润，无形中给其他的企业以很大竞争压力和利润驱动力，从而推动所有企业重视技术创新。技术创新是由市场的需要引起，企业通过组合各种创新资源，运用科学的方法与手段创造出新产品、新工艺，并进行生产，最终进行商业化，当它商业化成功、企业取得利益时，这项技术创新才算成功（也有人认为企业技术创新的过程还包括技术扩散）。在高新技术产业集群中，比邻而居的企业之间由于频繁的交往和经常性的合作，产生了面对面的观察与学习的便利性，一项技术创新很容易为其他企业所发现，其他企业通过对此项技术创新的消化、吸收与模仿，在此基础之上进行技术改良，又导致渐进性的技术创新不断发生，从而形成强大的挤压效应。另外，在产业集群中各行动主体因地域的接近、交往的频繁、亲友的情缘等因素形成与积累了丰厚的社会资本，减少了学习与交流的交易费用。企业只有进行技术创新，才能不断降低成本，不断提高产品质量和服务水平，从而更好地适应市场需求的变化，最终才能在激烈的市场竞争中生存和发展。企业发展了，由企业组成的高新技术产业集群才能生存、发展。同时企业只有进行技术创新才能实现产品、工艺的升级和换代，这也推动了高新技术产业集群技术水平和产业结构的优化和升级，从而增强了高新技术产业集群的活力，延长了高新技术产业集群的生命周期。企业技术创新能力是一个产业集群长久地保持竞争优势的关键。在产业集群内，企业的竞争力决定了产业集群的竞争力。在开放式市场经济条件下，企业面临的不仅仅是区域内、国内同行的竞争，而是全球同行的竞争，其中不乏本行的佼佼者。面对这么激烈的竞争和自身拥有资源的不足，企业要想生存下去的最好方法就是从我做起，提高自身的竞争能力——进行技术创新就是众多方法中较好的一个。无数公司成功、失败的经验教训已经证明了这一点。以市场需求为导向，进行技术创新，在提高企业竞争力的同时，也提高了以企业为基础的产业集群的竞争力。使高新技术产业集群在竞争中能生存下来，并不断发展，使技术创新成为高新技术产业集群竞争力的源泉。技术创新是一个极其复杂的过程，单个企业是难以支配创新的全过程的，因而企业与外部环境的联系就显得十分重要。在创新过程中集群企业不是孤立的，他们处于由客户、供应商、竞争者、大学、科研机构以及其他机构构成的社会网络中。企业技术创新是一个系统过程，在这个系统中，企业是技术创新的主体，也是创新投入、产出以及收益的主体，是创新体系的核心。但需要大学与研究机构、其他企业、政府、中介机构以及金融机构五大行动主体构成的技术创新支持系统。这种企业技术创新系统的发展很大程度上得益于产业集群。产业集群的技术创新网络反映了集群中创新行为主体之间的关系，通过横向、纵向的联结，信息、技术、资源在网络内部不断流动和优化配置，从而促进了集群中企业的技术创新行为。不仅产业集群内的同类企业之间要形成一种网络关系，更重要的是还要与非同类企业之间也要结成一定的网络关系。产业的区域集聚就为形成创新的产业网络奠定了基础。企业技术创新是一个动态的系统过程。首先，在产业集群内，由于有大量相关企业的存在，以及中介服务机构和消费者，需求信息流量大、快而且集中，使企业在感知市场动向方面比较方便，能够迅速抓住市场需求，把握市场机会，进行技术创新，以填补市场需求空白。在研发阶段，创新资源大量积聚，如人才、资金等，同时大家对彼此又十分了解，合作的可能性更大，这也降低了创新的风险。面对竞争的压力、利益的驱动力，各个企业必然积极主动地进行技术创新；在产品化阶段，由于集群内集聚了大量相关企业，以及由此形成的交易、技术、社会网络，各个企业通过分工与合作方式进行生产，既降低生产成本，又节省了创新时间，同时相匹配的创新也会在先创新企业的带动下进行起来，这种创新的波动效果会使新产品的相关配套设施迅速完备，加快新产品商业化的过程；最后，在商业化阶段，由于产业集群内已经形成了完善而发达的各种渠道和中介服务机构，加上产业集群本身已经形成的品牌效应，使商业化的时间更短，商业化成功的可能性也更大。集群呈现繁荣景象，完整的创新链形成。成熟的企业技术创新系统是一个高度动态的有序的自组织的创新系统，大量的渐进创新不断涌现出来，产品和工艺不断被更新，它们之间或是互相竞争、互相替代或是互相协同、互相促进。成熟的企业技术创新系统的根本动力来自多样化的市场需求、规模扩张以及子系统之间的竞争和协同。技术创新的真正意义和实际价值，不在于创新本身，而在于这种创新的扩散。技术创新对一个国家或地区经济的影响取决于创新成果在整个经济系统中的扩散效果。技术创新扩散是技术创新通过一定的渠道在潜在使用者之间传播采用的过程。技术创新通过技术扩散系统在潜在使用者之间传播、推广和应用，从而提高产业集群内各企业的技术水平，高集群内企业的经济效益和竞争能力。事实上，产业集群内并非每个企业都有能力和条件进行技术创新，少部分企业的技术创新对产业集群的经济增长、效率提高、竞争能力增强等多方面的影响，绝大部分是通过技术创新扩散形式实现的。也就是说，产业集群内技术创新的成功并不仅仅依靠技术的深度和创新的先进性，更大程度上还要根据市场的接受程度，即技术创新的扩散程度来判断。因此，从某种意义上讲，作为技术创新的后续过程，产业集群内技术创新扩散比技术创新更为重要。培育高新技术产业集群，需要加强技术创新能力与政府的相关政策作用。政府在高新技术产业集群技术创新能力提高的进程中应该积极制定培育政策，采取相关措施推进技术创新的顺利进行。第一，政府在扶植高新区发展时，一方面应增加R&D的投入，另一方面还应积极制定R&D优惠政策，给予积极创新的企业以一定的补偿。由于技术的非独占性，社会希望技术溢出越多越好，而从企业出发，创新的技术溢出越少越好，所以政府必须在二者之间保持一种平衡，使创新的私人受益率与社会受益率趋于协调。政府应建立健全知识产权保护法和完善的产权交易制度，保护创新主体的正当权益，并通过使创新者享有某种特定的津贴，比如税收优惠、利率优惠等政策，调动创新者的积极性。第二，制定有利于高新技术产业集群发展的人才培养和吸引政策，积极引进国内外发展高新技术企业的各种人才。鼓励大学和科研院所的科技人员、研究生以各种形式直接参与高新产业集群的技术创新活动，加强产学研的合作机制。政府通过建立和完善技术入股制度，科技人员持股经营制度、技术开发奖励制度等符合高新技术产业发展的分配形式，鼓励科技人员的技术创新。第三，完善风险投资机制，吸引风险投资机构参与到高新技术产业集群的技术创新中来，转化和扩大企业投资主体，解决高新技术产业发展中的资金“瓶颈”，以便有充足的资金投入给优秀的项目和有很大潜力的高技术项目，从而得到资金保障。积极寻求相匹配的国外直接投资，引进先进的技术、设备和先进的管理经验，为风险投资基金提供规范化的运作经验，从而有利于集群质量的改善和集群稳定地发展。高新技术产业集群是区域产业组织的一种形式，产业的空间集聚对产业创新起到了至关重要的作用。现实的经济发展表明，一个国家的经济增长越来越多地依赖于技术和信息，技术的进展已经成为经济增长的主要推动力，依靠科技进步，实现经济增长方式的明显转变。由于外部经济对高新技术产业发展的特殊意义，外部规模经济使得集聚区内的技术信息增加和共享，为创新提供了更多容易捕捉的机会，企业能更方便地接近市场，了解顾客的消费倾向，减少企业的学习成本，促进技术进步，加速企业的技术创新，推动社会经济的快速发展。

正向（经典）遗传学是通过生物的表型来推测其遗传物质的组成、分布和传递规律等，而反向遗传学是在已知基因序列的基础上，利用现代生物理论和技术，通过核苷酸序列的定点突变、缺失和插入等创造突变体并研究突变所造成的表型效应。随着基因组测序技术、侵染性克隆的构建技术、定点突变技术和报告基因的使用等，反向遗传学技术在研究植物病毒基因功能、侵染过程和致病机理等方面的应用越来越广泛。本文报道了该技术在研究马铃薯Y病毒（PVY）HC-Pro和甘薯褪绿矮化病毒（SPCSV）P22功能方面的部分结果。PVY HC-Pro基因由本实验室提供，SPCSV的有关基因由芬兰赫尔辛基大学Valkonen教授提供，PVX201质粒由Baulcombe教授提供。突变试剂盒（Quick Change XL Site-Directed Mutagenesis Kit）购自STRATAGENE公司，大肠杆菌菌株DH5α由本实验室保存，PCR突变引物由赛百盛公司合成。Figure 1 Symptoms of Nicotiana benthamiana plants inoculated with different constructs based on PVX 201将SPCSV P22、P28和RNaseIII等基因克隆到PVX201载体上，根据接种后出现的症状判断哪个基因能增强PVX对本氏烟的致病力。将PVY HC-Pro克隆到PVX201载体上，针对HC-Pro的KITC和IGN等位点设计合适的突变引物，参考突变试剂盒（Quick Change XL Site-Directed Mutagenesis Kit）说明进行突变。通过测序证实所得突变体的准确性。大量提取法提取质粒PVX201、PVXHC或相应的突变体，摩擦法接种本氏烟（Nicotiana benthamiana），观察所致症状的差别。PVX201载体在本氏烟上引起轻微的斑驳和褪绿花叶症状，但不引起植株的死亡。SPCSV P28和RNase III等基因连接到PVX201后对症状无影响，但P22能提高PVX对本氏烟的致病力，导致了接种植株的死亡，说明P22是致病性的增强子。携带P22的PVX（PVX-p22）首先在接种叶上引起坏死斑点。坏死斑点扩展后，沿着叶脉到达茎部，引起上部组织坏死，最终导致本氏烟整株枯死。RNA沉默抑制因子HC-Pro也能提高PVX对本氏烟的致病力。表达HC-Pro的PVX（PVX-HC）在接种后7天出现严重明脉和卷曲，10～14天时首先心叶出现坏死，随后整株萎蔫死亡。但在接种叶上没有坏死斑，看不到明显的扩展迹象。KITC是HC-Pro的一个重要基序，参与病毒的蚜虫传毒、协生和抑制RNA沉默等过程。我们在测定烟草脉带花叶病毒（TVBMV）全基因组序列时发现，TVBMV（YND分离物）HC-Pro KITC基序中的K变成了R，而且也有蚜虫传毒活性。我们把PVY HC-Pro的KITC突变成RITC后，再接种本氏烟，发现该突变仍能引起本氏烟植株的死亡。把K突变为A（突变体1，K52A）后，突变体也能引起本氏烟死亡，说明HC-Pro KITC基序中的K可能不参与和PVX的协生。但把KITC基序中的C缺失后（突变体2，C55Del）就不能引起植株死亡，说明KITC基序中的C对于协生作用是不可缺少的。对于HC-Pro其他突变体的功能分析正在进行中。

核盘菌是普遍存在的坏死性真菌病原，能够侵染75科408种植物。在寄主植物中尚未发现免疫种或单基因抗性，包括十字花科。然而在禾本科等非寄主植物中该病菌是不致病的或弱致病的。为研究非寄主抗性机制，我们用该病菌接种了竹子、小麦、玉米和油菜。接种后24 h，这些植物对病菌的反应是不同的，竹子和玉米上无病斑，小麦上有小的病斑，但不同品种有变化，而油菜上产生了大的病斑。扫描电子显微镜研究表明，接种的竹子叶表面形成了一层膜，但在光学镜下菌丝穿透进入了上表皮细胞。菌丝进入竹子和油菜叶表皮细胞的方式是不同的。在油菜上菌丝很快进入上表皮细胞和细胞间隙，但竹子中菌丝仅限于上表皮和叶肉细胞。我们推定禾本科植物叶表面物质和细胞壁成分可能是阻止菌丝进入细胞的重要障碍。需要进一步分析这些成分。Sclerotinia sclerotiorium(Lib.)de Bary is a ubiquitous necrotrophic fungal pathogen capable of infecting at least 408 plant species of 75 families.No highly resistant varieties or germplasm is found in hosts including Cruciferae plants.On non-host plants such as some Gramineae species,however,the pathogen is avirulent or weak virulent.To understand how these non-hosts resist the pathogen,we inoculated S.sclerotinia mycelium to the leaves of bamboo,wheat,maize and oilseed rape as well.There were different responses in these plants after 24 hpi(hours post inoculation).No lesion was found on bamboo and maize leaves.Small lesions were observed on wheat,but the lesion size varied among different cultivars.Larger lesions were observed on oilseed rape leaves than any other Gramineaes at earlier time after inoculation.The scanning electron microscope(SEM)study showed clearly that inoculated bamboo leaf formed a layer of membrane on the leaf surface,but the slides under a light microscope unveiled hyphae penetration into the epidermal cells.The modes that hyphae grew into the leaves were also different between bamboo and oilseed rape.The hyphal growthfast under the oilseed rape epidermal and in the intercellular space,but in bamboo the growth was limited in the epidermis and mesophyll cells.We assumed that surface substance and cell wall composition are important obstacles of the hyphal penetration in non-host Gramineae plants.Further work needs to be done to analyze these compounds in comparison with oilseed rape.

Rice stripe(RSV)has been known to distribute in rice areas all over the world,and it is very hard virus,transmitted by insect vectors,small brown planthopper(SBPH),Laodelphax striatellus,Fallen.Once the rice is infested,there is still no very effective measures to control,even the chemicals.The chemicals'effect is not ideal and more or less they could cause some environmental risks,so there is the common opinion in the IPM system that the rice varieties having resistance to rice stripe is one of the basic and effective measures to control this disease.In 2006 and 2007 for finding the resistant rice varieties that could be used for large scale in the field,the evaluation and screening of rice varieties were conducted in Jiaxing,Zhejiang Province.In 2006,there were 40 varieties provided for the experiement,just like Chunjiang 050,Xiushui 63,Y1,Zheda 510,Tai 03126,HZ586 and so on,and Jia 991 was set to be the control.Similar to 2006 studies,in 2007,there were 20 varieties used in 2006,and newly introduced into 17 varieties,just like Leyou 2,Jiaheyou 261,Bing 04～123,Jiashao 3.The control was still Jia 991.In 2006,the experiment was conducted in the yard of Shuangqiao Academic of Agricultural Science,Xiuzhou,Jiaxing.Last year in this plot rice was planted,and in winter no crop was planted.The water and fertilizer condition was good.The rice was seeded in 2th June,and transplanted to the field in 1st July.Randomed blocking design,and the size of every plot is 30m2,with three replications.The field management was as usual,except for no chemicals use for controlling the SBPH and RSV.In 2007,the experimental field was chose to north suburb of Jiaxing,where last year the RSV occurred hard.The experimental field condition and design were familiar with 2006,and total 111plots.Investigated Methods In 2006,after 5d from 1st July when the rice were transplanted,the investigation was conducted every 5d in field,till the diseases was stable,at that time the total rice tiller and the diseased tiller amount were recorded.Num.VarietiesDiseasepercentageinthefield(%)SSRP=0.05P=0.011Jiahe2156.03aA2Y25.33bB3Jiajing36485.24bB4Y33.9cC5Shaojing04-463.49dD6Jia991(CK)3.07eE7Yongjing04683.02efEF8Y62.88fgEFG9Tai04-42.83gFG10Xiushui032.73ghGH11Qianghu9142.73ghGH12Y102.59hiHI1336You7482.52ijHI14Xiushui092.51ijHI15ZH2512.42jkIJ16Xiushui1102.27klJK17Jingzhi202.27klJK18Y42.23lmJKL19Jia04-332.14lmnKLM20Jiahua12.11mnKLM21Xiushui632.04nLM22Jiahe2182nM23Zheda5101.99nM24Bing01-1131.74oN25R41011.69oN26Y51.59oN27Jingzhi270.94pO28Chunjiang0500.91pO29Chunjiang0510.91pO30Bing03-1230.88pO31Jiaheyou28880.87pO32Zheda5320.86pO33Y80.86pO34Y10.81pO35Ning04-450.45qP36Tai031260.44qP37HZ5860rR38Y70rR39Y90rR40JiaheyouTR0rRTable 1In 2007,after 15th May,when the seeds were seminated,the investigation was conducted periodically in seedling stage till 20th June,when the rice was transplanted,the total rice tiller and the diseased tiller amount were recorded.And in field,30th July,when the disease was stable,the same indexes were recorded.By the total rice tiller and the diseased tiller amount,the disease percentage could be got,and by DPS software the resistance of different rice varieties could be made with ANOVA method.From table 1,we could get that in 2006 the RSV occurred softly in the experimental field,the CK,Jia 991'disease percentage was just 3.07%.Shaonuo 04~46,Y3,Jiajing 3648,Y2,Jiahe 215's were higher than CK;but there were four varieties,Jiaheyou TR,Y9,Y7,HZ586,which no typical RSV was found.By ANOVA analysis,the resisstance of rice varieties were obviously different.Jiaheyou TR,Y9,Y7,HZ586,which no typical RSV was found,the resistance were the highest;the Yongjing 0468,Y6 and CK were in the same level and at P=0.01 there were no obvious difference;and Shaonuo 04～46,Y3,Jiajing 3648,Y2,Jiahe 215 resistance were weak.In 2007,in the field the RSV occurred seriously in the experimental field,the CK,Jia 991'disease percentage was 19.12%(Table 2).Disease percentage of Shi 1 and Yongjing 0468 were 27.8%and 25.65%,respectively;there were 16 varieties,for example Jia 991,the disease percentage were above 10%;and the disease percentage of HZ586,Chunjiang 051,Jiahe 218,Jiaheyou 555 and Y9 were below 2%.By ANOVA analysis,the resistance of these rice varieties were seriously different.Disease percentage of Shi 1 and Yongjing 0468 were obviously higher than CK,their resistance were weak;the disease percentage of HZ586,Chunjiang 051,Jiahe 218,Jiaheyou 555 and Y9 were far below from other variety,their resistance were high;and others resistance were in the middle level.In 2007,in the seedling field the disease percentage of Bing 04～132,Zheda532,Xiushui 09,Xiuishui 110 and Bing 05～15 were all above 5%;the disease percentage of was just 0.07%,and in the Chunjiang 051 there was no RSV found;Other varieties percentage of disease were in the middle of 5%and 0.07%(Table 2).Num.VarietiesDiseasepercentageinthefield(%)SSRP=0.05P=0.01VarietiesDiseasepercentageintheseedlingfield(%)SSRP=0.05P=0.011Shi127.8aABing04-1325.68aA2Yongjing046825.65aAZheda5325.6aA3Bing04-0819.62bBXiushui095.39aAB4Jia991(CK)19.12bBXiushui335.24abAB5Xiushui11018.5bBXiushui1104.85abcABCTable 2 Evaluation of rice varieties resistance to RSV (Jiaxing, 2007)Num.VarietiesDiseasepercentageinthefield（%）SSRP=0.05P=0.01VarietiesDiseasepercentageintheseedlingfield（%）SSRP=0.05P=0.016Bing05-1517.83bBCShi14.34abcdABCD7Bing01-11317.76bcBCJiahua14.34abcdABCD8Y517.33bcBCYongjing04684.24abcdABCDE9Jiahua116.5bcdBCBing05-154.15abcdeABCDEF10Xiushui3316.4bcdBCY53.78abcdefABCDEFG11Ning04-4516.26bcdBCBing04-083.66abcdefgABCDEFGH12Bing04-13215.75bcdBCJia991（CK）2.9bcdefghABCDEFGHI13Zheda53215.69bcdBCY22.88bcdefghABCDEFGHI14Y215.18bcdBCDBing01-1132.81bcdefghiABCDEFGHI15Shi215.06bcdBCDNing04-452.77cdefghijABCDEFGHI16Xiushui0914.99bcdBCDY12.66cdefghijABCDEFGHI17Y112.96cdeBCDEQianghu1712.52cdefghijkABCDEFGHI18Qianghu17112defCDEBing05-1142.48cdefghijkABCDEFGHI19Bing03-019.22efgDEFShi22.26defghijkBCDEFGHI20Bing04-1138.25fghEFGBing03-012.14defghijkBCDEFGHI21Jiaheyou6127.18ghiEFGHBing04-1131.69efghijkCDEFGHI22Bing03-1235.76ghijFGHJiaheyou2611.39fghijkDEFGHI23Leyou25.42ghijFGHJiaheyou6121.23ghijkDEFGHI24Jiaheyou2615.23ghijFGHBing03-1231.11hijkDEFGHI25Jiaheyou16204.76ghijFGHY71hijkEFGHI26Shaonuo04-464.36hijFGHChunjiang0500.99hijkEFGHI27Jiashao34.3hijFGHJiahe2180.94hijkFGHI28Chunjiang0503.22ijFGHLeyou20.9hijkFGHI29Y73.18ijFGHJiaheyou62230.72hijkGHI30Jiaheyou62233.1ijFGHJiaheyou5550.7hijkGHI31台031262.97ijFGHJiaheyou16200.5hijkGHI32Bing05-1142.9ijFGHY90.38hijkHI33HZ5861.83jGHHZ5860.32ijkI34Chunjiang0511.81jGHShaonuo04-460.24jkI35Jiahe2181.78jGHJiashao30.24jkI36Jiaheyou5551.53jHTai031260.07kI37Y90.94jHChunjiang0510kI续表2By ANOVA analysis,the different resistance of these rice varieties also existed.the disease percentage of Bing 04～132,Zheda532 and Xiushui 09 were higher,and their resistance were weak;the disease percentage of six varieties,Chunjiang 051,Tai 03126,HZ586,Shaonuo 04～46,Jiashao 3 and Y9,were lower,and they had comparatively high resistance.Through the rice varieties screening for resistance to rice stripe virus(RSV)in the seedlingstage and in the field in Jiaxing,in 2006 and 2007,the difference of rice varieties resistance to RSV could be found,and the resistance trends between different developmental stage and different year kept in the same trends.Chunjiang 051,Y9,Jiahe218,Jiaheyou 555,Tai 03126 and Bing 03~123,and so on,had the high resistance to RSV.Though most of the results showed that the varieties resistance behave the same in different developmental stage and different year,we also should notice that few varieties did not obey this trends,for example,Shaonuo04～46,in 2006 in the field it showed very weak resistance,but in 2007 in the seedling field it showed high resistance.This perhaps tell us that just use the index of disease percentage is not enough,and at the same time we could ignore that there is still no very clear criterion to evaluate the varieties resistance to RSV.These factors could influence our evaluation.In 2006 the RSV occurred softly in the experimental field,the CK,Jia 991 disease percentage was just 3.07%,but in 2007 the CK,Jia 991's disease percentage was 19.12%,far higher than that in 2006.That is because in 2007 we chose the field where in year before the RSV occurred seriously,and advanced the seeding date and transplanted date accordingly,which the two steps could make the optimal RSV occurring conditions.On other hands,in the same cultivated condition,the disease percentage different varieties could behave 10-folder difference,it could show us clearly that the varieties resistance could exert important role in the RSV IPM system.Research was funded by a grant from Zhejiang province Science and Technology Bureau.

植物的诱导抗病性，又称系统获得性抗性，是植物在一定的诱抗剂刺激下，对随后的病原菌侵染具有抵抗性的特征。植物诱抗剂又名激发子，一般将能够诱导寄主防卫反应的生物来源和非生物来源的物质统称为激发子。这些物质在很低浓度下即可被植物识别为信号物质，诱发植物自身的免疫系统，最终使植物获得抵御病害的能力。寡糖类激发子是人类研究的最早、最为充分的一类激发子，并且由于其具有良好的环境相容性，因此是很有发展潜力的生物农药。壳寡糖已经应用于生产，防治作物病害，但对其进行结构修饰的寡糖，其诱抗活性还不清楚。新的寡糖—褐藻酸钠寡糖诱抗活性也未见报道。本文研究了稀土络合的壳寡糖（壳寡糖-铈配合物）以及褐藻酸钠寡糖诱导烟草抗烟草花叶病毒，为其作为生物农药提供依据。1.1.1 供试药剂 壳寡糖-铈配合物、壳寡糖，由中国科学院大连化学物理研究所研制。褐藻酸钠寡糖，由中国农业科学院饲料所研制。1.1.2 供试植物 枯斑三生烟（Nicotiana tobacum L.SamSun NN）。1.1.3 供试毒源 烟草花叶病毒（TMV），本实验室保存于普通烟上。接种病毒汁液为每克含TMV的烟草病叶，加入5倍体积0.05mol/L的磷酸缓冲液（pH7.0），在研钵中研磨后纱布过滤。1.2.1 试验处理 供试药剂：对照药剂壳寡糖50μg/ml，喷雾。供试药剂壳寡糖-铈配合物浓度分别为1μg/ml，10μg/ml，25μg/ml，50μg/ml，100μg/ml，喷雾；供试药剂褐藻酸钠寡糖浓度为25μg/ml，50μg/ml，100μg/ml，喷雾。1.2.2 试验方法 选取大小一致6～8叶期的烟草植株，叶面喷雾施药。24h后汁液摩擦接种TMV病毒。在病毒汁液中加入少量石英砂，用毛笔蘸取汁液摩接种。枯斑三生烟苗采用半叶法接种，每株接4片叶。接种后每天观察发病情况。待全面发病后，调查病斑数。重复3次。抑制率（%）=[（对照叶片病斑数-处理叶片病斑数）/对照叶片病斑数]×100%最初的试验结果表明（表1），壳寡糖-铈配合物对抑制烟草花叶病毒引起的枯斑有抑制作用。在1～100μg/ml的浓度范围里，25μg/ml的诱抗效果最好，抑制率为55%，但是略低于阳性对照壳寡糖50μg/ml，抑制率63.9%。处理斑点数抑制率（%）壳寡糖-铈配合物1μg/ml43±18c37.025μg/ml31±13b55.050μg/ml38±18cd44.0100μg/ml42±19c37.7壳寡糖50μg/ml24±14b63.9CK68±26a—表1 壳寡糖-铈配合物不同浓度喷施对烟草花叶病毒病的防效 （P由于1μg/ml的壳寡糖-铈配合物依然有诱抗活性，并且25μg/ml的诱抗活性较好，因此将取浓度10μg/ml的壳寡糖-铈配合物，进行诱抗活性的检测试验。结果表明（表2），浓度为10μg/ml的壳寡糖-铈配合物比25μg/ml具有更好的诱抗活性，抑制病毒产生枯斑的抑制率为67.4%。但是与25μg/ml没有显著性差异。因此，10～25μg/ml的壳寡糖-铈配合物具有良好的诱抗活性，说明壳寡糖与稀土的络合物可以在低于壳寡糖的使用浓度时，依然具有较高的诱抗活性。处理斑点数抑制率（%）壳寡糖-铈配合物10μg/ml43±17c67.425μg/ml57±13cd56.750μg/ml73±22d45.0100μg/ml107±27a18.9壳寡糖50μg/ml28±13b78.7CK132±46a—表2 壳寡糖-铈配合物不同浓度喷施对烟草花叶病毒病的防效 （P在褐藻酸钠诱导抗性的试验中，试验结果表明，在25～100μg/ml的浓度范围内，褐藻酸钠具有诱抗活性，可以显著抑制病毒引起的枯斑的产生。其中浓度为50μg/ml诱导抗性效果最好，抑制率为71.8%，25μg/ml的褐藻酸钠也有较高的诱抗活性，抑制率为67.4%，均略高于壳寡糖50μg/ml（抑制率64.1%）。处理斑点数抑制率（%）褐藻酸钠25μg/ml59±27bc67.450μg/ml51±21c71.8100μg/ml74±32b59.1壳寡糖50μg/ml65±26b64.1CK181±32a—表3 褐藻酸钠不同浓度喷施对烟草花叶病毒病的防效（P多糖类化合物在自然界中分布广泛，是生命物质的重要组成成分。它不仅能够控制细胞的分化、分裂，调节细胞的生长和衰老以及维持生命有机体的正常代谢，还能够调节动植物细胞免疫以及其间信息的传递。目前，多糖作为生物激发子用于抗植物病害研究比较多，其中已报道氨基寡糖素、毛头鬼伞多糖、硫酸化的葡聚糖以及脱氧半乳聚糖[1～4]等具有诱导烟草抗烟草花叶病毒的生物活性。褐藻胶是一种来源于褐藻细胞壁的水溶性酸性多糖，主要从海带、巨藻、马尾藻等褐藻中提取得到，具有独特的结构和生物活性。褐藻胶由α-L-古罗糖醛酸和β-D-甘露糖醛酸通过1，4糖苷键连接而成的直链多糖[5]。褐藻胶还有很强的抗病毒活性，如抑制TMV，抑制程度随着褐藻胶浓度的增加而增强，且随着褐藻胶中古罗糖醛酸含量的增加而增强。电镜分析表明，TMV在培养基中呈单一分散悬浮，加入褐藻胶后则形成团聚物。团聚物的形成阻止了TMV在被感染细胞表面的脱衣壳过程，而阻止了TMV的RNA穿过细胞膜，从而防止感染[6]。但由于其凝胶性强，不容易被吸收，在应用方面收到很大的限制，将其水解为寡糖后，水溶性好，利于吸收。因此本文研究褐藻酸钠水解为褐藻酸钠寡糖后的生物活性，以期在生产实践中具有更加广泛的应用。结果发现褐藻酸钠寡糖具有良好的诱抗活性，并且好于阳性对照壳寡糖，但是其具体机理还有待于进一步的研究。近几年研究发现，稀土离子，尤其是Ce，有较广泛的抑菌作用，而且有降解有机磷的能力。壳聚糖-铈配合物对黄瓜中的硫磷农药残留有一定的降解作用，其降解产物是氨基对硫磷，基本解除了毒性[7]。研究已经发现壳寡糖能够诱导烟草抗烟草花叶病毒，本文研究了壳寡糖-铈配合物是否依然保持具有诱导抗性的活性。结果表明，壳寡糖-铈配合物尽管诱抗效果不如壳寡糖明显，但仍然具有较高的诱抗活性，至于是否有降解有机硫磷的作用，需要进一步的研究。经过化学修饰的壳寡糖-铈配合物可以改变壳寡糖的理化特征，产生新的活性，这对于加强寡糖应用的广泛性和多功能性具有重要的价值。

核盘菌（Sclerotinia sclerotiorum）所致的油菜菌核病是毁灭性的。抗病性鉴定方法是抗病材料筛选和育种的关键。本研究探讨了一种有效的田间病害圃鉴定筛选的方法，该方法中维持适中的病害压力是鉴定区别油菜品系抗性的关键。病害圃中每年连作油菜，在播种前每行施两粒菌核。在开花期利用喷雾系统喷雾保湿。于成熟期按0～4级分级调查病害。在两年的试验中，90个品系发病率在3.3%～100%。发病率和病情指数在重复之间显著相关。小区的病情指数和相对抗性指数基本为正态分布。研究结果表明该方法是有效的、有用的和灵敏的。Sclerotinia sclerotiorum causes a highly destructive disease in oilseed rape(Brassica napus).Methods for identification of resistance to S.sclerotiorum are crucial to screening and selection of resistance materials.In the study,we described a field disease nursery method efficient for resistance screening of breeding lines or germplasm of oilseed rape where maintaining of a suitable disease pressure is considered to be most important in order to differentiate levels of resistance existed in different lines.In the disease nursery,S.sclerotiorum inoculum had been maintained by growing oilseed rape consecutively and by placing two sclerotia in each row before sowing in each of the previous four seasons.During the flowering time,all plants were sprayed with water using a spray system.At maturity,disease severity was assessed on a 0~4 scale and disease index was calculated.In tests of two years,percent diseased plants of 90 lines(3 replicates in each year)ranged from 3.3%~100%.The percent of diseased plants and disease indices were significantly correlated between replicates(P<0.05).The frequency distributions of both disease indices(each plot)and relative resistance indices were in a normal form while the frequency distribution of percent diseased plants was negatively skewed.These data indicated that the method is efficient and useful to differentiate resistance of oilseed rape varieties.

中二软占是广东省农业科学院水稻所以粳籼21为母本，长丝占为父本杂交育成的早、晚兼用常规优质稻品种，于2001年通过广东省农作物品种审定。中二软占的丰产性和适应性好，米质良好，但中感稻瘟病。作者等将中二软占品种的种子经密封后送到酒泉卫星发射基地（部分中二软占种子留在地面作为非诱变原种对照），于2003年11月3日随“中国返回式科学试验卫星”升空，经过18天的太空旅行，于11月21日返回地面。2004年早造将中二软占诱变和非诱变原种对照单株种植，采用稻瘟病菌株GD0193接种到3到3片半叶的种苗上，发病7天后调查，792株经过空间诱变的种苗，病级为0～3级的抗病植株有208株，占总数的26.3%；病级为4～5级的植株有368株，占46.5%；病级在6级以上的有216株，占27.3%；80株原种对照种苗的病级均在6级以上。试验结果表明，中二软占的种子经过返回式卫星搭载后，对稻瘟病产生抗性变异，其中抗性明显提高的占26.3%；抗性比原种提高（病级0～5级）的植株数占72.7%。对中二软占空间诱变SP2代材料的抗性分离规律进行研究。从空间诱变中二软占SP1中选取33株抗病和2株感病植株的种子作为SP2的接种材料，原种中二软占作对照，接种稻瘟病菌株采用GD0193菌株。空间诱变中二软占SP1的2个感病植株在SP2抗性没有产生分离，33个抗病植株在SP2抗性产生分离，而且各株系抗感分离的比例也不一样。对33个抗病SP2株系抗感分离的比例进行X2分析，结果表明有21个株系抗感分离比例符合理论比值3：1，说明这21个株系可能受一个位点的抗性基因控制；有8个株系抗感分离比例符合理论比值15：1，说明这8个株系可能受两个位点的抗性基因控制。另外，有4个株系抗感分离比例既不符合3：1也不符合15：1。表明这4个株系的遗传基础比较复杂。由于目前对水稻空间诱变的染色体变异的遗传机理还不是很清楚，诱变除了导致基因的位点突变以外，也可能导致染色体的缺失、重复、倒位、易位等畸变。这些畸变将影响水稻的性状，而且使其在SP2的基因的分离规律变得更复杂。从33个空间诱变中二软占抗病植株的SP3-SP4代株系中连续两造各筛选出5株农艺经济性状较好的单株，考种及抗病性鉴定结果表明，与原种中二软占比较，抗病性有不同程度的提高，而且穗长、总粒数、结实率、粒长、谷粒长宽比、千粒重等性状与原种中二软占的相比，也有不同程度的提高。将33个空间诱变中二软占抗病植株和1个感病植株的SP4代株系进行抗谱测定，采用38个不同致病型代表菌株接种结果，原种中二软占和空间诱变感病株系的抗谱分别为29.0%和34.2%，33个空间诱变抗病株系中，抗谱达到80%以上的诱变株系有32个，其中抗谱在90%以上的诱变株系有24个，抗谱在80%～90%间的诱变株系有8个。中二软占是优质但中感稻瘟病的品种，从其空间诱变后代中有望筛选出对稻瘟病抗性及农艺经济性状比原种好的株系，可为抗稻瘟病育种提供新材料及优良抗源。目前作者等正重点开展有关优质、抗病的中二软占诱变品系的抗性遗传基础分析、抗病基因标记定位、空间诱变抗性变异机理研究等。