井冈霉素A对水稻纹枯病菌的毒力和作用机理研究

根据水稻纹枯病菌 Rhizoctonia solani AG- 1IA在含系列浓度井冈霉素 A马铃薯葡萄糖琼脂培养基 (PDA)上的菌丝生长速率 ,计算出药剂的毒力回归方程为:Y=3.2 30 9+0 .872 0 X,r=0 .9910 ,药剂的 EC50 =10 6 .9μg/ m L,EC75=6 34.5 μg/ m L。在含 5 0 0 μg/ m L井冈霉素 A的 PDA上水稻纹枯病菌的菌丝生长抑制率为 74 .1% ,而田间水稻植株上人工接菌的药效试验结果表明 ,5 0 μg/ m L药液喷洒后 7d和 14 d的防效即可分别达到 77.4 %和 76 .7% ,即药剂在 PDA平板上的理论抑制作用仅是田间活体植株上对病菌实际作用效果的 1/ 10。比较室内毒力和田间药效试验的结果可以看出 ,井冈霉素 A具有对病原菌和寄主植物双重作用的特性。研究首次发现 ,在室内培养基上不能有效抑制病菌生长的 1μg/ m L的井冈霉素 A可以在水稻植株未喷药部位产生防御水稻纹枯病的作用 ,且能够持续诱导植物防御反应相关酶——过氧化物酶 (PO)和苯丙氨酸解氨酶 (PAL)的活性增高,表明该药剂可以激发水稻抗性防卫反应的表达。     

井冈霉素诱导水稻防御纹枯病反应机理的研究

 本研究通过比较井冈霉素在室内培养基(in vitro)条件下和水稻活体植株(in vivo)上对水稻纹枯病菌的毒素有效中浓度EC₅₀、通过田间和盆栽药试验(不同喷药方式)、通过对井冈霉素处理烟草后TMV的枯斑数目的变化、通过测定井闪霉素处理珊西烟和水稻后体内抗性防卫相关酶活性的动态变化,取得在下几方面的结果。     

新月弯孢CLE菌株胞外蛋白对水稻纹枯病的诱导抗性及其菌种鉴定

以井冈霉素为对照,比较了从感病稗草上分离的CLE菌株胞外蛋白增强水稻对纹枯病的抗性作用.结果表明,接种纹枯病菌后,CLE胞外蛋白处理的SOD和POD的活性比对照有不同程度的上升,MDA含量在接种48h后显著低于对照.CLE胞外蛋白处理显著降低了水稻植株的纹枯病病情指数,防治效果提高了17.9%.基于ITS序列的系统发育分析表明,菌株CLE与新月弯孢Curvularia lunata(有性阶段:异旋孢腔菌Cochliobolus lunata)系统发育关系最密切,以98.9%的ITS基因核苷酸序列相似性处于同一分支.结合其形态特性,将其鉴定为新月弯孢菌.     

几种药剂对水稻纹枯病的防治效果探究

使用250g/L嘧菌酯SC 30g/667m~2、240g/L噻呋酰胺SC 30ml/667m~2、5%己唑醇SC 80ml/667m~2、5%井冈霉素SP 100g/667m~2防治水稻纹枯病,于水稻纹枯病发病初期施第1次药,以后每隔7d施1次,共施3次,3次施药后10d各药剂的防治效果均达67.9%~88.9%。其中,嘧菌酯、噻呋酰胺和己唑醇这3种药剂的防效好且相当,为88.0%~88.9%,井冈霉素处理的防效差显著低于以上3种药剂处理的防效,为67.9%。     

防治水稻纹枯病药剂田间筛选试验

正水稻纹枯病是水稻上常发病害之一,由立枯丝核菌侵染水稻引起。主要为害叶鞘、叶片,致叶片枯死,使结实率下降,千粒重减轻,一般造成产量损失10%~30%,严重时50%以上。近年来,纹枯病受菌源量、气候及水稻种植密度等因素影响,发生呈趋重态势。生产中实际应用以井冈霉素为主的防治纹枯病的药剂,常规推荐剂量的防治效果逐年下降。2015年笔者在大田条件下开展了9种药剂防治水稻纹枯病的药效试验,比较     

氯胺磷与井冈霉素对水稻纹枯病菌的混配增效作用研究

在室内恒温条件下,用菌落直径法测定了氯胺磷、井冈霉素及其5种不同比例的混配对水稻纹枯病菌的毒力。结果表明,85%氯胺磷可溶性粉剂和5%井冈霉素水剂对水稻纹枯病菌的制剂EC50是168.2 mg/L和467.8 mg/L,前者毒力大于后者;两者以4〖DK1〗∶1、1〖DK1〗∶1混配具有显著的增效作用,增效系数分别为2.26、2.25。考虑综合经济效益和增效作用两方面,1∶1配比为最佳。     

井冈霉素A对水稻抗性相关酶活性的影响

测定了用井冈霉素A处理后3、7、14和21天后盆栽水稻植株的海藻糖酶、内切几丁酶和内切几丁酶和内切β-1，3-葡聚糖酶的活性。结果表明，药剂处理后14天内水稻植株体内的海藻糖酶活性明显比对照(清水处理)下降；内切几丁酶的活性一直比对照明显增高；内切β-1，3-葡聚糖酶的活性在药剂处理后第3天最高，之后逐渐下降。海藻糖酶活性下降、内切几丁酶和β-1，3-葡聚糖酶活性动态增高的结果与盆栽水稻叶面药剂处理控制纹枯病的效果和持续时间相吻合。这为揭示井冈霉素的作用机理和深入理解农用抗生素的作用方式提供了新的线索。     

30%苯醚甲环唑·丙环唑乳油防治水稻纹枯病效果

用30%苯醚甲环唑·丙环唑乳油（爱苗）与对照药剂20%井冈霉素可溶性粉剂防治水稻纹枯病。试验结果表明,30%苯醚甲环唑·丙环唑乳油对纹枯病的平均防治效果达84.14%,比20%井冈霉素可溶性粉剂的防治效果（76.52%）提高7.62个百分点。示范用药区每667 m2产量527.9 kg,比20%井冈霉素每667 m2产量（496.7 kg）增产31.2 kg,增产6.28%。示范区每667 m2减少施药用工2.5元,增加效益62.9元。建议每667 m2用30%苯醚甲环唑·丙环唑乳油30 mL对水45 kg在纹枯病发生初期对水稻叶面进行均匀喷雾。     

30%爱苗乳油防治水稻纹枯病试验

经田间试验,30%爱苗乳油15ml/667m2在纹枯病发病初期和隔10d施药2次的处理防治纹枯病效果最佳,达到65.3%;30%爱苗乳油15ml/667m2在破口前三天和齐穗期用药2次跟20%井冈霉素粉剂30g/667m2在纹枯病发病初期和隔10d施药2次的处理防治效果分别达到61.7%和61.9%,50%水稻病菌清可湿性粉剂50g/667m2在破口前三天和齐穗期用药2次处理防治效果为57.2%。30%爱苗乳油对水稻有增产效果,2个处理比空白对照分别增产7.69%和6.15%,比20%井冈霉素处理增产1.54%的水平分别高6.15和4.61个百分点。     

水稻纹枯病拮抗菌的筛选及田间小区防治水稻纹枯病的效果

水稻纹枯病 (Ｒｈｉｚｏｃｔｏｎｉａｓｏｌａｎｉ)是水稻三大病害之一。当前 ,生产上主要用井冈霉素加以防治 ,但长期使用此药 ,已使纹枯病菌产生了抗药性。本研究针对四川稻区纹枯病菌ＡＧ Ｉ融合菌丝群 ,进行拮抗细菌的筛选及生防潜力研究。1　材料和方法1 1　供试菌　水稻纹枯病菌菌丝融合群ＡＧ Ｉ菌株及供试木霉 (Ｔｒｉｏｈｏｄｅｒｍａｖｉｒｄｅ) ,由四川农业大学水稻研究所病理研究室分离 ;水稻品种两优 6 81Ｆ1代种 ,由四川农业大学水稻研究所杂交稻中试开发公司提供。1 2　拮抗细菌的分离和筛选　将从各地采集的水稻根、茎、…     

12种杀菌剂防治水稻纹枯病田间试验研究

本文报道了12种杀菌剂防治水稻纹枯病的田间试验研究。结果表明:噻呋酰胺24%悬浮剂339g/hm2、嘧菌酯25%悬浮剂500g/hm2、丙环唑25%乳油750g/hm2在2次药后15d对水稻纹枯病的防治效果分别为91.5%、88.1%、86.6%,显著高于其他处理;肟菌·戊唑醇75%水分散粒剂防效为77.0%,稍次于丙环唑25%乳油;其他8种杀菌剂的防效在54.1%~68.7%之间,防效不太理想;井冈霉素20%可湿性粉剂的防效仅为56.6%,故笔者认为在水稻纹枯病大发生年份,尽量选用其他高效的杀菌剂进行预防和防治。     

Infection of Rice Plants with the Sheath Blight Fungus Causes an Activation of Pentose Phosphate and Glycolytic Pathways

The response of key regulatory enzymes of the pentose phosphate and glycolytic pathways in disease development was assessed in genetically-related rice plants resistant and susceptible to the sheath blight fungus, Rhizoctonia solani. The plants were grown and maintained under greenhouse conditions and inoculated at 50% flowering. Uninoculated healthy plants served as controls. The activities of pentose phosphate pathway enzymes (glucose-6 phosphate dehydrogenase and 6-phosphogluconate dehydrogenase) increased more than two-fold in both the resistant and susceptible plants. Activities of ATP- and pyrophosphate-dependent phosphofructokinase and phosphoenolpyruvate phosphatase increased in infected plants while activity of phosphoenolpyruvate carboxylase in infected plants was lower than in the healthy plants. Furthermore, for enzymes with increased activity, the levels were higher in the resistant line than in the susceptible line. The enhancement of the enzyme activities correlated well with the post infection period. These data suggest that altered carbohydrate metabolism in sheath blight infections may play an important role in modulating the rice plant's response to infection. The isolation of an infection-induced gene encoding a basic enzyme of pentose phosphate and glycolytic pathways could be used to develop plants with more resistance towards sheath blight disease.     

广西水稻内生细菌的动态分布及其对水稻纹枯病菌的拮抗作用

从广西稻区74种水稻品种中采集了222个水稻标样,分离出1903株内生细菌。经形态和生理生化测定,确定这些菌株分属于芽孢杆菌属Bacillus、鞘胺醇单孢菌属Sphingomonas、土壤杆菌属Agrobacterium、伯克霍尔德氏菌属Burkholderia、肠杆菌属Enterobacter和成团泛菌属Pantoea。其中,Bacillus和Enterobacter为主要类群,Bacillus为优势类群。水稻内生细菌的类群随不同的水稻品种和栽培地区而变化。水稻内生细菌在植株器官中的分布以根部数量最多,其次是叶鞘和叶。内生细菌的总量在水稻生育期的变化趋势是从苗期到孕穗期上升,从灌浆期到乳熟期下降。分离到的1903株内生细菌中,有412个菌株对水稻纹枯病菌Rhizoctoniasolani有拮抗作用。     

3种药剂防治水稻纹枯病、稻曲病和稻瘟病田间药效试验

采用田间药效试验方法,比较3种药剂对水稻纹枯病、稻曲病、稻瘟病的防治效果。结果表明:3种药剂对水稻纹枯病、稻曲病、稻瘟病都有一定防效。其中75%肟菌戊唑醇水分散粒剂225 g/hm2对水稻纹枯病、稻瘟病防效最好,防效分别为85.74%、85.19%;43%戊唑醇悬浮剂225 mL/hm2对稻曲病的防治效果最好,防效为88.25%。综合防治效果表明,75%肟菌戊唑醇水分散粒剂150～225 g/hm2对水稻纹枯病、稻曲病、稻瘟病的防效最好,43%戊唑醇悬浮剂225 mL/hm2对稻曲病和纹枯病防治效果较好,在实际生产上可广泛应用。     

水稻内生细菌B196的鉴定及其对水稻纹枯病的防治作用

从水稻体内分离得到的细菌菌株B196对水稻纹枯病菌Rhizoctonia solani的生长有较强抑制作用.通过形态学和生理生化鉴定及16S rDNA序列分析,将菌株B196鉴定为巨大芽孢杆菌Bacillus megaterium.采用浸种和喷雾的方法将菌株B196接种到水稻植株后,均能在稻株体内回收到该菌株,表明菌株B196能在水稻体内定殖.菌株B196对水稻纹枯病的盆栽和田间防效分别为64.29%和55.13%.     

铜绿假单胞菌ZJ1999对水稻纹枯病的防治及其在水稻上的定殖

利用拮抗菌铜绿假单胞菌ZJ1999产生的粗提液进行防治水稻纹枯病研究的结果表明，抑制病菌侵染的活力随着粗提液浓度提高和处理时间的延长而增强。该菌株的定殖时间与最初引进时的浓度密切相关，其最低应用浓度为10^8cfu／ml，在接种纹枯病病菌后第一天的喷施防效最佳。拮抗菌ZJ1999在发病的秧苗、成株期植株茎杆和叶片上，14d后的菌量分别维持在10^2-10^3和10^3～10^4cfu／g。     

Effects of Elevated Atmospheric CO(2) Concentration on the Infection of Rice Blast and Sheath Blight

ABSTRACT The effect of elevated atmospheric CO(2) concentration on rice blast and sheath blight disease severity was studied in the field in northern Japan for 3 years. With free-air CO(2) enrichment (FACE), rice plants were grown in ambient and elevated ( approximately 200 to 280 mumol mol(-1) above ambient) CO(2) concentrations, and were artificially inoculated with consist of Magnaporthe oryzae. Rice plants grown in an elevated CO(2) concentration were more susceptible to leaf blast than those in ambient CO(2) as indicated by the increased number of leaf blast lesions. Plants grown under elevated CO(2) concentration had lower leaf silicon content, which may have contributed to the increased susceptibility to leaf blast under elevated CO(2) concentrations. In contrast to leaf blast, panicle blast severity was unchanged by the CO(2) enrichment under artificial inoculation, whereas it was slightly but significantly higher under elevated CO(2) concentrations in a spontaneous rice blast epidemic. For naturally occurring epidemics of the sheath blight development in rice plants, the percentage of diseased plants was higher under elevated as opposed to ambient CO(2) concentrations. However, the average height of lesions above the soil surface was similar between the treatments. One hypothesis is that the higher number of tillers observed under elevated CO(2) concentrations may have increased the chance for fungal sclerotia to adhere to the leaf sheath at the water surface. Consequently, the potential risks for infection of leaf blast and epidemics of sheath blight would increase in rice grown under elevated CO(2) concentration.     

Host-Specific Toxin Production by Rhizoctonia solani, the Rice Sheath Blight Pathogen

ABSTRACT Rhizoctonia solani, the rice sheath blight pathogen, produces a toxin that reproduces all symptoms of the disease. The toxin has been partially purified and it was found to be a carbohydrate containing glucose, mannose, N-acetylgalactosamine, and N-acetylglucosamine. The toxin was also detected in infected leaves. Highly virulent isolates produced more toxin than less virulent isolates. Several R. solani isolates from rice and one each from cotton and tomato produced a similar toxin. All rice cultivars tested were susceptible to the pathogen and sensitive to the toxin. Host specificity of the toxin has been demonstrated using hosts and nonhosts of the pathogen.     

水稻细菌性条斑病和纹枯病生防细菌的复筛、室内防效及应用评价

采用活体生测法对前期工作中离体初筛出的5株水稻细菌性条斑病生防菌和5株水稻纹枯病生防菌分别进行复筛、温室防效测定和应用评价。结果表明,菌株GN233、GN222和GN223的菌悬液对水稻苗期细菌性条斑病有一定的防治效果,其中菌株GN233对细菌性条斑病的温室防效最好,达到28.90%,而药剂"稻丰TM多·福"可湿性粉剂的温室防效为34.20%;5株生防菌对水稻纹枯病均有不同防治效果,其中菌株GN222和GN211菌悬液的防治效果较好,分别达到44.4%和27.8%,而药剂"稻丰"可湿性粉剂的防效为33.3%;此外,筛选出的生防菌株GN222、GN233和GN211均对水稻生长具有促生作用。本研究结果可为水稻细菌性条斑病和水稻纹枯病的生物防治奠定基础。     

哈茨木霉在水稻体内的定殖及其对水稻纹枯病抗性的影响

以具有抗腈菌唑标记哈茨木霉TUV-13菌株的分生孢子悬浮液对水稻种子分别进行浸种、蘸根、叶面接种,栽培至2叶1芯期,从秧苗各组织分离回收菌株TUV-13。对经菌液处理的秧苗进行显微及超微观察结果表明,浸种处理能使TUV-13菌株在水稻秧苗的根、茎、叶中稳定定殖;而蘸根处理、叶面接种,TUV-13菌株只能在处理的局部区域定殖。TUV-13菌株定殖后,水稻秧苗与抗病相关的酶活性显著提高,对水稻纹枯病防效达82.9%。