利用gusA基因在水稻组织中示踪和定量水稻白叶枯病菌的方法

 水稻白叶枯病菌(Xanthomonas oryzae pv. oryzae, Xoo)从自然孔口水孔或者伤口处侵入水稻叶片,在维管束中定殖、繁殖和扩展,引起典型的叶枯症状。可视化这个动态的病程过程和快速定量水稻组织中细菌的群体是Xoo-水稻互作研究中亟待突破的技术难点。本研究在PXO99^A菌株中表达gusA基因,将其置于lacZ启动子、hrpX启动子和不含有(T₁)₄终止子的hrpX启动子下,构建了3个示踪菌株PXO99^A_GUSRBS、PXO99^A_GUSX和PXO99^A_GUSX-。水稻上毒性测定结果显示,这3个示踪菌株与野生型PXO99^A展现相同的毒性。利用示踪菌株,通过注射接种法,能够观察到Xoo在水稻维管束中定殖和扩展的动态变化;通过喷雾接种法,能够观察到Xoo从叶尖或者叶缘侵入水稻叶片引起发病的特性;发现PXO99^A_GUSX和PXO99^A_GUSX-比PXO99^A_GUSRBS能够更加灵敏地反映这些病程。同时发现,PXO99^A_GUSRBS的细菌数量与受其侵染的水稻组织的GUS活性显著正相关。本研究也评价了利用GUS活性测定法精确和快速地定量水稻组织中细菌群体的可行性。以上结果表明这套GUS系统是非常有效的,能够示踪病原菌的侵染过程和监测细菌在水稻组织中的群体数量,这将为Xoo-水稻互作研究提供有力的技术支持。     

稻瘟菌双分病毒MoPV2特性研究

稻瘟病是稻瘟菌引起的一种世界性病害,每年造成水稻大幅减产。真菌病毒是指能够在真菌体内进行复制和繁殖的病毒,可以作为生物防治的资源。本实验从发病的水稻叶片上采用单孢分离的方法获得纯化培养的稻瘟菌菌株YC13。菌株YC13携带多条dsRNA片段,其中片段F1与Magnaporthe oryzae virus 2(MoV2)的Coat Protein(CP)和RNA-dependent RNA polymerase(RdRp)的氨基酸序列均具有99%的同源性,确定为MoV2的基因组;片段F4、F5序列与双分病毒Penicillium stoloniferum virus F(Ps V-F)的RdRp和CP的氨基酸序列分别具有69%和63%的同源性,命名为Magnaporthe oryzae partitivirus virus 2(MoPV2)。MoPV2的基因组含有2条dsRNA:dsRNA 1编码RdRp,dsRNA 2编码CP。根据MoPV2的RdRp编码的氨基酸序列将MoPV2归属于双分病毒科(Partitiviridae)G ammapartitivirus属,是一种新的真菌病毒。通过病毒粒子转染,将MoPV2转到稻瘟菌菌株RB11。与菌株RB11相比,带毒菌株RB11T25的分生孢子产生量显著减少,并且对大麦活体的致病性也有所降低,但其他生物学特征均无明显的影响。本研究在稻瘟菌中发现了一种新的真菌病毒,该病毒能够使稻瘟菌致病力下降,为稻瘟病的防治提供了潜在的病毒资源。     

拮抗水稻白叶枯病菌链霉菌的筛选、鉴定和防效研究

为寻找水稻白叶枯病天然生防药剂,本研究利用共培养和牛津杯法分离筛选植物根际土壤放线菌,共分离纯化获得65株放线菌菌株.在8株能够拮抗水稻白叶枯病菌Xanthomonas oryzae pv.oryzae(Xoo)放线菌菌株中,Sr-63菌株对水稻白叶枯病菌拮抗能力最强,其发酵液抑菌圈直径为46.4 mm±2.3 mm....     

水稻白叶枯病菌北方菌株的分子鉴别和致病型分析

为了阐明水稻白叶枯病菌(Xanthomonas oryzaepv.oryzae,Xoo)北方菌株的毒性组成,对2008年和2009年从辽宁、吉林、河北、山东稻区采集的103个菌株进行了PCR分子鉴定,并利用一套水稻抗白叶枯病近等基因系作为鉴别品种,进行了致病性测定。结果表明,用3种不同引物对测定菌株基因组进行PCR扩增,均可以鉴别出与Xoo代表菌株完全一致、而与水稻条斑病菌明显不同的特异性扩增片段带型。6个水稻鉴别品种对测定菌株的感病反应明显不同,抗病性强弱依次为IRBB5IRBB13IRBB3IRBB14IRBB2IRBB24。103个菌株对6个水稻鉴别品种表现出毒力多样性,92个菌株(89.32%)表现与9个标准小种(R1~R9)代表菌株相同的致病型,其中36个R5和R8菌株为优势菌株,9个菌株为对6个水稻品种都致病的R9强毒力菌株;此外,新发现了其余11个菌株(10.68%)具有7种新的致病型(R10~R16)。     

稻瘟病标样中分离真菌的分析和鉴定

 通过分离稻瘟病标样中的病原真菌,回接稻瘟病菌普感的水稻品种—丽江新团黑谷,得到多个不能引发稻瘟病的菌株。随机选取2个致病的分离菌株和4个不致病的分离菌株,以稻瘟病菌Guy11为对照,观察它们的菌落形态和色泽、分生孢子形态和大小、分生孢子梗形态等生物学特性,发现6个分离菌株与Guy11的形态均较为相近。附着胞形成试验发现,不致病的分离菌株在疏水表面不能形成附着胞,但外源添加cAMP可使部分孢子形成附着胞。PCR扩增分离菌株的ITS、β-tubulin、actin和calmodulin等序列,测序并根据比对结果绘制相应的系统发育树,鉴定表明分离的2个致病菌株9-1、214属于Magnaporthe oryzae;4个不致病菌株18-1、18-2、122和132为梨孢属真菌Pyricularia。不致病菌株的发现和鉴定可为稻瘟病菌侵染机制研究和稻瘟病防治奠定基础。     

水稻类穗颈瘟梨孢菌新种的生物学特性及不同水稻品种抗性分析

稻瘟病菌引起的穗颈瘟严重影响水稻产量和质量。前期对江苏省稻区连续多年监测首次发现一类能引起类似穗颈瘟的梨孢菌新种Pyricularia sp. jiangsuensis,发生率高且在不同年份稳定存在。为了解该病原菌与稻瘟病菌之间的差异，本研究对该病原菌代表菌株P. sp. jiangsuensis 18-2与稻瘟病菌菌株P. oryzae Guy11在生长、产孢、各种胁迫及不同品种对两种病害的抗性等方面进行比较。结果表明，P. sp. jiangsuensis 18-2在PDA、CM和SDC三种培养基上的生长速度明显快于P. oryzae Guy11,但是P. sp. jiangsuensis 18-2的气生菌丝较为稀疏。在细胞壁胁迫因子和氧化压力下，P. sp. jiangsuensis 18-2对外源逆境的耐受性较P. oryzae Guy11更强，该病原菌更适应对外界胁迫的应答。进一步分析江苏省推广的主栽品种对类穗颈瘟的抗性，发现一些主栽品种对P. sp. jiangsuensis 18-2和P. oryzae Guy11引起的穗颈瘟存在抗性差异，鉴定筛选出品种镇稻448、盐粳1...     

影响水稻纹枯病菌营养体亲和性分化的因子

 为了探明影响水稻纹枯病菌营养体亲和性分化的因子,将水稻纹枯病菌菌株cx-2在不同水稻品种继代接种,并在含不同杀菌剂、具不同pH及不同温度条件的PDA平板上继代培养,用对峙法测定继代菌株与原始接种菌株的营养体亲和性。此外,对营养体亲和性分化菌株与原始菌株的AFLP指纹图谱进行比较。结果显示,在供试的30个水稻品种上连续接种4次后,从9个水稻品种中分离出与原始菌株营养体不亲和的菌株。菌株在不同pH值的PDA平板继代培养4次后,在pH偏碱性端(pH 10、pH 11)开始出现营养体亲和性分化的菌株。在不同农药和温度条件下继代培养10次的菌株中没有分离到营养体亲和性分化的菌株。营养体亲和性分化菌株与原始菌株的AFLP指纹图谱没有差异。     

一株淡剑灰翅夜蛾病原性真菌莱氏绿僵菌的多基因序列鉴定

为明确从草坪害虫淡剑灰翅夜蛾Spodoptera depravata(Butler)罹病虫体分离得到的病原性真菌菌株DT2011N7的分类地位,通过形态学观察、BLAST序列比对以及基于ITS、β-tubulin和rpb2a的单基因序列分析和3个基因联合的多基因序列分析对菌株进行了鉴定。结果显示,菌株DT2011N7在萨氏麦芽糖酵母浸粉培养基上培养时,菌落初期呈白色,产孢后表面密布孢子呈淡绿色;分生孢子为椭圆形,大小为3.5~5.5μm×2.0~2.8μm。BLAST序列比对结果显示菌株DT2011N7与莱氏绿僵菌Metarhizium rileyi一致性最高,达99%~100%;在3个单基因及多基因系统进化树中,该菌株均与莱氏绿僵菌聚在同一进化分支中,自展值达99~100。结合形态学特征、同源性比对结果及系统进化树分析,将菌株DT2011N7鉴定为莱氏绿僵菌M.rileyi。     

稻瘟菌群体中dsRNA的多样性及稻瘟菌菌株QSP5中病毒对寄主生物学性状影响的研究

 真菌病毒在真菌中广泛存在,一些真菌病毒可以影响病原真菌营养生长、产孢和色素形成等性状。本文研究了真菌病毒在水稻稻瘟菌中的多样性以及其对寄主生物学性状的影响。采用单孢分离的方法从发病水稻叶片上分离获得了120个稻瘟菌菌株,其中约52%携带dsRNA片段。菌株QSP5被2个基因组为dsRNA的病毒即产黄青霉病毒1-C(Magnaporthe oryzae chrysovirus 1-C, MoCV1-C)和稻瘟菌病毒3(M. oryzae virus 3, MoV3)所侵染。对菌株QSP5进行单个的分生孢子纯化,获得了仅携带MoV3的菌株QSP5-9。菌株QSP5与QSP5-9的产孢量、菌丝形态以及菌落形态存在明显差异,经研究推测MoCV1-C与菌株QSP5 的产孢能力衰退、菌丝生长和产色素异常相关。同时对MoV3的稳定性进行了初步的研究。从稻瘟菌菌株QSP5获得了100个单孢分离物,通过对随机挑选的40个单孢分离物进行检测,结果表明这些分离物100%携带MoV3,只有部分单孢分离物携带MoCV1-C。另外,从稻瘟菌菌株QSP5-9获得了94个单孢分离物,对随机挑选的45个单孢分离物进行检测,结果表明这些分离物中均含有与菌株QSP5-9大小相同的dsRNA片段。根据以上结果推定MoV3在稻瘟菌菌株QSP5和QSP5-9及其无性后代中具有一定的稳定性。     

大丽轮枝菌培养性状的变异

 对棉花,茄子、辣椒等植物上分离到的大丽轮枝菌(Verticillium dahliae kleb)的36个菌株进行了培养性状变异的研究。试验以分生孢子稀释培养的方法,检查单孢菌落的变异率.从野生型(A型)菌株分离到的92,947个单孢菌落,形成绒毛型(B型)菌落的变异率为5.85%,形成菌膜型(C型)菌落的变异率为0.07%。在绒毛型菌株的1,773个单孢菌落中,形成菌膜型菌落的变异率为0.19%。大丽轮枝菌野生型菌株培养性状的变异率,因试验菌株、单孢个体、营养条件、菌种保存温度和保存时间不同而异.绒毛型变异体的培养性状比较稳定.根据试验结果,探讨了菌种保存的方法.     

Changes in agronomic practices and incidence and severity of diseases in winter wheat in England and Wales between 1999 and 2019

In continuation of the annual national surveys of winter wheat, which began in 1970, samples from between 250 and 350 randomly selected wheat crops in England and Wales between 1999 to 2019 were visually assessed for disease symptoms during the milky ripe development stages (GS 73–75). Septoria tritici blotch was the most prevalent and severe foliar disease each year, although annual levels fluctuated considerably and there was no overall significant change over the two decades. Incidence of brown rust, yellow rust, take-all, and barley yellow dwarf virus also showed no significant overall change during the survey period, whereas glume blotch, powdery mildew, eyespot, and sharp eyespot all showed significant decline. Fusarium ear blight has significantly increased in both incidence and severity, causing a serious epidemic in 2012, when 96% of crops were affected. Tan spot has been the third most prevalent foliar disease since 2009 although severity is still very low. Regional disease levels were consistent over the two decades, providing reliable baselines to measure changes in seasonal disease severity. There were significant changes in agronomic practice with a rise to predominance of minimum tillage over the use of ploughing, decreases in overall disease susceptibility of cultivars grown, a major increase in the use of oilseed rape in the rotation and a long-term trend towards earlier sowing. Fungicide use increased considerably, with over 98% crops sprayed and an average of 3.5 applications made per crop each year since 2014. Implications of changes over the last 21 years are discussed.     

吡虫啉和百菌清在设施内外葫芦和黄瓜中的残留特性比较

采用高效液相色谱和气相色谱法,分别研究了吡虫啉和百菌清在薄膜大棚设施内外葫芦叶和黄瓜中消解动态及其在葫芦和黄瓜中的残留量,并结合气象因子对产生残留差异的原因进行了分析。样品中的吡虫啉经乙腈和盐酸溶液提取,中性氧化铝和弗罗里硅土层析柱净化后,用高效液相色谱检测;百菌清经乙腈提取,中性氧化铝层析柱净化后,用气相色谱检测。结果表明:吡虫啉在设施内外葫芦叶和黄瓜中均消解迅速,施药7 d后,其在设施内外葫芦叶上的消解率分别为90.4%和98.7%,在黄瓜中的消解率分别为67.8%和85.9%;而百菌清在葫芦叶上的消解速率均比在黄瓜中的稍慢,施药7 d后其在设施内外葫芦叶上的消解率分别为15.4%和38.1%,在黄瓜中的消解率分别为87.8%和91.5%。表明2种农药在设施外2种蔬菜上的消解速率均快于设施内的。两种农药均是在设施外葫芦及黄瓜中的残留量低于设施内的,而降雨和光照强度可能是引起农药在设施内外蔬菜上残留差异的主要因子。     

中国的沙暴、尘暴及其防治

沙尘暴在进入 90年代以来有进一步加剧趋势 ,其原因在于此期我国西北地区气候干暖化态势明显 ,人类超负荷开发资源加剧 ,从而导致沙尘暴的频繁发生 ,但总体上仍属于正常的灾害现象。我国沙暴只能发生于干旱半干旱区 ,尘暴则可波及半湿润与湿润区 ,由此而论 ,北京的沙尘暴属于尘暴范畴 ,北京不会形成沙漠区。防治沙尘暴必须采取水、土、植被综合防治措施 ,基本对策是 :1 .搞好流域为单元的水土资源合理利用规划 ,进行水土保持综合防治 ;2 .增加地表植被复盖 ,搞好防护林体系建设 ;3 .减轻土地利用强度 ,恢复提高土地抗蚀能力 ;4.加强管理体系建设 ,依法建设生态环境。建议国家设立水土保持为主要职能的生态环境建设委员会 ,统一协调布署我国的生态环境建设工作。     

Plant-pathogen interactions of sunflower and Macrophomina phaseolina in vitro and in vivo

The relative pathogenicity of isolates of Macrophomina phaseolina was comparable both on sunflower tissue cultures and on mature plants and seedlings. The relative susceptibility of the different sunflower lines in vitro showed a similar pattern for cotyledon callus cultures, but not for immature embryo cultures. Although these protocols appear to be unsuitable for the selection of novel disease resistance, they do offer the potential for a rapid, non-destructive screen for resistant material.     

2017年与2014年西安极端高温天气及其环流特征对比分析

借助观测资料与FNL全球分析资料,对比研究2017年与2014年西安高温天气基本特征与有利环流形势,结果表明：① 2 a西安均发生了40 ℃以上的长时间持续高温天气,其中2014年属于常规高温年份,而2017年西安高温则提前1个月发生,高温的提前发生主要是因为南亚高压强于正常年份同期强度;② 不同于我国南方地区的闷湿高温,西安高温属于干性高温,且昼夜温差较小,由此造成24 h对人体的不适;③ 详细描述了西安高温发生的典型环流特征,即南亚高压与西太平洋副热带高压（简称副高）同时增强,并在对流层中高层相互贯通;④ 南亚高压是影响我国西北地区的主要热源基地,在较大经向度的有利环流背景下,强风速可将热气团向南向东深度输送至下游地区（即西安）;⑤ 在“上辐合、下辐散”的散度场配置下,西安500 hPa以下高空维持明显的下沉气流,加之有利的局部要素相配合,最终造成该地区高温天气的发生。     

Trends and expectations for research and technology in weed science in Thailand

There are many possible ways to improve the economic crisis in Thailand, and it is agreed that development of agricultural production is ideal for improving the economic situation in an agricultural country such as Thailand. A strategic plan for agricultural and agro‐industry research is included in the national research agenda and can be classified into nine groups covering different research areas. Most research is based on the agricultural production of four main product groups: (i) crops; (ii) aquatic animals/plants and fisheries products; (iii) poultry, livestock and animal products; and (iv) forest resources. Trends in research and development in weed management for crop production will continue to support the food demands and the development of efficient production of quality products.     

Pesticide residues in soil and foodstuff I. Chlorinated pesticides in cattle feed and milk produced in orchard and non-orchard areas

Milk, hay and silage produced in orchard and non-orchard areas have been analysed for their content of chlorinated pesticides. The residue levels in milk produced in orchard areas were about double those in milk produced in non-orchard areas. The levels in hay were much higher (30% up to sevenfold) in the hay produced in orchard areas and the levels in silage from the two areas showed small differences. Milk collected after cattle had been grazing in an orchard for 3 to 4 days contained 10% more pp′-DDT and 2-, 3-, 7- and 15-fold morepp′-DDE, pp′-TDE and heptachlor epoxide, gamma-BHC and pp′-TDE olefin [1-chloro-2,2-bis(p-chlorophenyl)ethylene], respectively, than did the samples collected one day before the cattle grazed in the orchard.     

Comparative ecophysiology of grain sorghum and Abutilon theophrasti in monoculture and in mixture

Selection of crop genotypes that are more competitive with weeds for light interception may improve crop yield stability in the presence of weeds. The effects of interference on ecophysiological characteristics of Abutilon theophrasti Medic. and three morphologically diverse grain sorghum hybrids was evaluated to determine the relative tolerance and suppressive ability of the three hybrids and specific traits that may contribute to those differences. A tall hybrid was more tolerant to A. theophrasti interference than two medium stature hybrids. Early leaf area growth of two medium-stature sorghum hybrids was reduced by A. theophrasti interference, whereas early growth of a tall hybrid was unaffected. The height of A. theophrasti was greater than two moderate-stature hybrids but lower than the tall hybrid. Greatest leaf area density (L_D) of the tall sorghum hybrid was above that of A. theophrasti , whereas greatest L_D of medium-stature hybrids was below that of the weed. In monoculture, the partitioning of new biomass to various plant organs was similar among sorghum hybrids, whereas the tall sorghum hybrid partitioned less biomass to leaves and more to stems than medium hybrids in mixture. The results indicate that the three hybrids differ in their susceptibility to A. theophrasti competition. Crop traits that may contribute to greater crop competitiveness include greater maximum height and its growth rate and greater height of maximum leaf area distribution.