玉米黑粉菌基因组编码蛋白作用位点的计算机预测

利用已公布的玉米黑粉病菌基因组全序列数据及信号肽预测软件SignalP v3．0、亚细胞器中蛋白定位分布预测软件TargetP v1．01、跨膜螺旋结构预测软件TMHMM v2．0和膜锚定位点预测软件Big-PI Predictor预测分析了玉米黑粉病菌基因组编码蛋白的作用位点。结果表明,在6522个ORF中,具有分泌功能的有543个,占全基因组基因总数的8．3％;作用位点在线粒体的有1552个,占全基因组基因总数的23．4％;具有跨膜结构的有1269个,占全基因组基因总数的19．5％;锚定在膜上的有56个,占全基因组基因总数的0．9％。     

玉米小斑病菌T小种毒素诱导对玉米叶片苯丙氨酸解氨酶活性的影响

分别采用低浓度玉米小斑病菌Hel minthospolium maydis T小种毒素(HMT毒素)和玉米小斑病菌T小种培养滤液中的提取蛋白及菌丝细胞壁的提取液,预处理不同玉米品种3叶期叶片后再接种高浓度HMT毒素,在无菌条件下培养5 d后测量叶片病斑大小,并测定玉米叶片内苯丙氨酸解氨酶(PAL)活性变化。结果表明:只有纯化的低浓度HMT毒素能够作为激发子诱导玉米获得系统性广谱抗性,但不同玉米品种所需的最适合浓度有差异;TC103以质量浓度0.025μg/mL毒素预处理效果最好,PAL活性最高;TB37和TMo17 2个自交系,以质量浓度分别为0.025μg/mL和0.050μg/mL的毒素预处理效果最好。     

燕麦散黑穗病防治药剂筛选及其对燕麦幼苗生长的影响

为更好的防治燕麦(Avena sativa)散黑穗病(Ustilago avenae),筛选可行杀菌剂并测定其对病原冬孢子萌发及燕麦幼苗生长的影响,采用水琼脂平板培养冬孢子萌发法和培养皿滤纸发芽法测定5 种杀菌剂对散黑穗病菌冬孢子萌发影响以及药剂拌种对燕麦种子发芽、干物质重、根系性状的影响。结果表明:33.5%喹啉铜悬浮剂对燕麦散黑穗病病原菌冬孢子萌发抑制率为100%,且对种子发芽、干物质积累、根系生长具有促进作用;45%咪鲜胺水乳剂对燕麦散黑穗病病原菌冬孢子萌发抑制率为100%,但其拌种的燕麦种子发芽、干物质积累、根系性状均低于对照;25%嘧菌酯悬浮液、40%氟硅唑乳油、25%苯醚甲环唑乳油对燕麦散黑穗病冬孢子萌发均具有较高抑制作用,且对燕麦种子发芽、干物质积累和根系性状均无影响,其施药剂量分别为75 g·hm^-2,60 g·hm^-2和1000倍液。     

Demography of Digitaria sanguinalis: Effect of the emergence time on survival,reproduction, and biomass

Knowledge of weed population dynamics is crucial for designing effective weed management practises. A field experiment was carried out at Torre Marimon (near Barcelona, north‐eastern Spain) in 2006 and 2007 in order to study the effects of the seedling emergence time on Digitaria sanguinalis fitness. Three and four cohorts were monitored in 2006 and 2007, respectively. In 2007, the seedling density was fourfold greater than in 2006. At the end of the growing season, no statistically significant differences in survival were detected among the cohorts in 2006 (the mean survival rate was 88%); in contrast, in 2007, individual survival varied depending on the cohort, ranging from 25–88%. The reproductive traits and seed production were significantly influenced by the emergence time. In the cohorts that emerged very close in time, the individuals of the first cohort on average had more than threefold the amount of seed production than those of the last cohort. However, not all the surviving individuals were able to reproduce because they were infected by the smut, Ustilago syntherismae.     

玉米尾孢菌、弯孢菌叶斑病严重流行及防治对策

近几年来,由于气候适宜和感病品种多年的大面积种植,导致我国玉米种植区的玉米尾孢菌、弯孢菌叶斑病的危害越来越重,辽宁、河北、河南等地均有发生,尤以辽宁发生最为严重,一般减产10%～20%,个别地块的感病品种几乎绝产,所以必须引起高度重视,应以推广抗病品种为重点,采取合理的品种布局及药剂防治等进行综合防治。     

The mechanism of resistance to sterol 14α demethylation inhibitors in a mutant (Erg 40) of Ustilago maydis

Resistance to DMI fungicides is a problem in both agriculture and medicine. Several mechanisms of resistance exist, but, as yet, few have been characterised in field resistant strains of plant pathogens. One approach to evaluating the role of mutations in the sterol 14α demethylase (14DM) target site requires cloning this gene and confirming its identity by complementation in an appropriate mutant. The azole‐resistant mutant, Erg 40, of Ustilago maydis which is totally blocked at the 14α demethylation step in sterol biosynthesis seems to be suitable for such expression studies. Transformation of Erg 40 with a plasmid containing the yeast 14α demethylase (CYP51A1) gene removed the block in sterol biosynthesis and generated azole‐sensitive transformants. Detailed analysis of these transformants failed to detect the presence of the yeast gene and suggested, instead, that changes in sterol biosynthesis resulted simply from the transformation protocol and not from the incorporation of extracellular DNA. Subsequent sequence analysis has revealed a mutation in the 14α demethylase gene of Erg 40. The results suggest that azole resistance in Erg 40 is not simply controlled by this mutation but involves some additional regulatory function, and consequently Erg 40 is not suitable for complementation studies with CYP51A1 genes. © 2000 Society of Chemical Industry     

哈茨木霉SH2303防治玉米小斑病的初步研究

哈茨木霉SH2303是本实验室分离获得的1株具有生防效果的菌株,该菌株能够较好的防治玉米小斑病。通过离体叶片试验确定哈茨木霉SH2303诱导玉米抗小斑病的持效期达15 d。盆栽及大田试验表明,防治玉米小斑病防效分别达到78.1%和56.3%。盆栽试验表明,哈茨木霉 SH2303处理的叶片在挑战接种小斑病菌后第36 h,玉米体内防御反应酶系PAL和SOD活性达到峰值。同时,防御基因Pal和Sod的表达水平也明显上升。综合分析表明,哈茨木霉SH2303的诱导抗性作用是防治玉米小斑病的重要机制之一。     

谷子黑穗病田间接菌方式试验

谷子黑穗病是山西省谷子的一个主要病害,近年来有加重的迹象。试验通过对谷子黑穗病设立不同的接菌方式和接菌的定量指标,分析接菌效果,以便准确地鉴定谷子黑穗病的发病情况,更好地研究谷子黑穗病,具有较强的实际指导意义。     

低浓度玉米小斑病菌C小种毒素培养滤液诱导寄主抗性的研究

利用低浓度玉米小斑病菌C小种毒素培养滤液作为激发子诱导玉米获得抗病性。以一对同核异质玉米B37自交系为试材,采用离体叶片接种法检测适宜诱导抗性的低浓度玉米小斑病菌C小种毒素培养滤液作为激发子诱导玉米抗病性的适宜诱导浓度,测定与抗病性相关酶的变化。经用1∶50和1∶60的低浓度玉米小斑病菌C小种毒素培养滤液预处理植株,再接种高浓度(1∶10)毒素培养滤液处理的病斑面积分别为(0.30±0.14)和(0.36±0.17)mm2,而对照为(2.70±0.24)mm2,是处理的7.5~9倍,差异极显著。经0~72 h的动态检测,以1∶60预处理效果为最佳,与对照相比,苯丙氨酸解氨酶(PAL)活性平均提高了23.4%,过氧化物酶(POD)活性平均提高了65.9%,有害物质丙二醛(MDA)的含量平均降低了28.2%。叶片内部所产生的生化反应与叶片表面的抗性病理反应相吻合,证实低浓度玉米小斑病菌C小种毒素滤液本身能够成功地作为激发子来诱导寄主-玉米获得抗性。     

菰黑粉菌MAPKK同源基因UeMkk1的全长克隆及表达

菰黑粉菌(Ustilago esculenta)是菰(Zizania latifolia)植株体内的内生真菌,其二型态转换与茭白孕茭密切相关,而丝裂原活化蛋白激酶(mitogen activated protein kinase,MAPK)途径在真菌二型态转换中具有重要调控作用.本研究利用酵母型及菌丝型菰黑粉菌的差异蛋白表达及转录组分析数据,克隆了菰黑粉菌中一个丝裂原活化蛋白激酶激酶(mitogen activated protein kinase kinase,MAPKK)基因UeMkk1(GenBank登录号:KR870332).该基因cDNA序列全长2 204 bp,开放阅读框2 043 bp.与模式菌酵母的MAPK途径蛋白进行聚类分析表明,UeMkk1属于MAPKK蛋白,NCBI中Blast比对结果及进一步的系统发育分析表明,UeMkk1与黑粉菌属真菌的Mkk1同源性较高,其中与大麦坚黑穗病菌(Ustilago hordei)的MKK1一致性达到84％,其丝/苏氨酸双特异性蛋白激酶催化结构域在不同真菌中高度保守.同时,本研究通过大肠杆菌(Escherichia coli)原核表达系统成功表达并从蛋白裂解上清液中纯化得到了纯度较高的UeMkk1蛋白.另外,对不同碳源诱导后菰黑粉菌的生长特征观察及UeMkk1的表达分析表明,蔗糖能诱导菰黑粉菌菌丝的形成及生长,UeMkk1的表达量在菌丝生长后期下调表达;PDA、葡萄糖及麦芽糖培养基中菰黑粉菌保持酵母型生长,UeMkk1呈周期性上调表达.以上研究工作为进一步开展UeMkk1基因的功能研究,阐明其在菰黑粉菌二型态转换及茭白孕茭中的作用提供了基础材料.