番茄褐斑病菌产毒培养条件及其毒素的致病范围

对番茄褐斑病菌(Helminthosporiurn carposaprum)产毒条件和毒素对不同番茄品种的毒性进行了研究,结果表明,不同的pH值、温度、光照条件、培养天数所制备的毒素毒力差异显著,病菌的最佳产毒条件是室温25℃,光照12 h、pH值为6、振荡培养15 d;不同植物对病菌毒素的敏感性不同。     

苹果褐斑病菌侵染对苹果叶片光合机构功能的影响

为了探究苹果褐斑病菌侵染对苹果叶片光合机构的伤害机制,以‘寒富’苹果为试材,研究苹果褐斑病菌侵染对苹果叶片光合作用和光系统功能的影响。结果表明：随褐斑病菌侵染加重（叶片感病程度分0、1、2、3、4和5级）,叶片的叶绿素a含量和总叶绿素含量持续下降,其中2～5级与对照相比差异显著,病菌侵染提高了叶片类胡萝卜素含量,但仅以2级与对照差异显著。苹果褐斑病菌侵染显著降低了叶片的净光合速率（Pn）,3～5级病叶的Pn分别较对照下降44．9％、56．6％和70．3％,而胞间CO2浓度（Ci）上升,说明非气孔因素是光合作用的主要限制因子。褐斑病菌侵柒影响了光合电子传递效率,随病菌侵染程度加重,光系统Ⅱ反应中心、供体侧放氧复合体（Wk）和受体侧（Vj）受到的伤害加重,并引起苹果叶片PSII的光合性能指数用PIABS和PSI受体侧末端电子受体的量子产额（φRo）急剧下降。褐斑病菌侵染加重了苹果叶片的膜脂过氧化程度,1～5级感病叶片的丙二醛（MDA）含量均显著高于对照,引发超氧化物歧化酶（SOD）及过氧化物酶（POD）活性的上调。以上结果表明,苹果褐斑病菌侵染引起叶片光合色素降解,对PSII反应中心、受体侧和供体侧造成伤害,进一步影响了PSI的电子传递效率,并导致叶片膜脂过氧化,造成苹果叶片光合能力下降。     

西芹种子子浸提液对黄瓜枯萎病菌的化感作用

为探讨西芹种子浸提液对黄瓜枯萎病菌是否有化感作用及其化感作用强度的大小,采用蒸馏水、乙醇、丙酮作为浸提剂,获得西芹种子的浸提液.用生长速率法研究其对黄瓜枯萎病菌的化感作用.结果表明:西芹种子的水、乙醇、丙酮浸提液都对黄瓜枯萎病菌有化感作用,浓度越大化感作用越强;50 mg·ml-1浓度的3种浸提液处理后144 h时与对照相比抑制黄瓜枯萎病菌蒸馏水浸提液为31.1%,乙醇浸提液为49.6%,丙酮浸提液为57.5%;乙醇、丙酮浸提液的化感作用强度大于蒸馏水浸提液.     

黄瓜种子及其萌发期的化感作用研究

以大白菜、萝卜、番茄和黄瓜种子为受体,采用实验室培养皿种子发芽生物测试法研究了黄瓜种子浸提液、种子萌发、胚根和芽苗分泌物、芽苗腐解物和芽苗浸提液的化感效应。结果表明:(1)黄瓜种子浸提液对大白菜、萝卜、番茄和黄瓜种子萌发均有化感抑制作用,即黄瓜种子内含有某些化感抑制物质。(2)在水浸提过的黄瓜种子萌发过程中,它不仅对其近邻套种的大白菜、萝卜和番茄种子萌发产生化感抑制作用,而且其胚根和芽苗分泌物对后茬播种的4种蔬菜种子发芽也表现出不同程度的化感抑制作用;黄瓜芽苗腐解物和芽苗水浸提液也对各受体蔬菜种子发芽与生长产生不同程度的化感抑制作用,且随着腐解芽苗量的增加或浸提液浓度的升高,各受体蔬菜种子的发芽指标值、化感效应指数值和综合效应值随之降低。(3)黄瓜种子浸提液及芽苗各器官的化感物质对黄瓜种子的萌发与生长产生了自毒作用,且黄瓜芽苗腐解物、芽苗浸提液、胚根及芽苗分泌物对受体黄瓜的自毒作用均为最大。研究发现,黄瓜种子浸提液、种子萌发时期以及芽苗各器官的化感物质主要是通过抑制受体胚根的生长而起化感抑制作用,即受体蔬菜种子胚根对化感效应最为敏感;因黄瓜种子及萌发期释放化感物质的途径有所不同,导致受体大白菜、萝卜、黄瓜和番茄的化感响应也不相同;在黄瓜种子萌发和芽苗生长的早期,化感物质即开始在芽苗体内进行合成与积累,一部分可通过胚根和芽苗分泌途径释放到环境中,另一部分可通过芽苗腐解途径释放化感物质,并对受体蔬菜种子萌发与生长表现出较强的化感抑制作用。     

两株镰孢菌的鉴定及其粗毒素对甜瓜幼苗的化感作用

从甜瓜枯萎病发病植株及其根际病土中分离到8株真菌,以甜瓜品种“西甜1号”为材料,采用回接试验和种子萌发试验确定真菌分离物对甜瓜的致病性和生长抑制作用;通过测定盆栽幼苗根系诱导酶活性、抗性物质含量及细胞膜相对透性,研究两株有害真菌粗毒素对甜瓜幼苗的化感作用;根据形态学特征及ITS序列分析对两株有害真菌进行初步鉴定.结果表明： 两株有害真菌TF和HF粗毒素对甜瓜种子萌发以及胚轴、胚根生长具有抑制作用,可导致甜瓜幼苗根系丙二醛(MDA)含量、可溶性蛋白含量及细胞膜相对透性增加,其中TF粗毒素原液处理下甜瓜幼苗根系MDA含量和细胞膜相对透性较对照分别增加108.6%和40.6%.两株有害真菌粗毒素可提高甜瓜幼苗根系保护性诱导酶活性,其中,TF粗毒素10倍稀释液处理下根系苯丙氨酸解氨酶(PAL)和过氧化物酶(POD)活性较对照分别增加25.6%和23.2%;HF粗毒素原液处理下根系PAL活性较对照提高30.0%.两株有害真菌TF和HF初步鉴定为木贼镰孢菌(Fusarium equiseti)和层出镰孢菌(F. proliferatum).两株镰孢菌虽然不能通过回接侵染甜瓜,但能通过分泌毒素影响甜瓜正常生长和生理生化代谢,同时提高甜瓜根系保护性诱导酶活性,具有有害和有益双重作用,其化感危害是引起甜瓜连作障碍的主要原因之一.     

两株镰孢菌的鉴定及其粗毒素对甜瓜幼苗的化感作用

从甜瓜枯萎病发病植株及其根际病土中分离到8株真菌,以甜瓜品种“西甜1号”为材料,采用回接试验和种子萌发试验确定真菌分离物对甜瓜的致病性和生长抑制作用;通过测定盆栽幼苗根系诱导酶活性、抗性物质含量及细胞膜相对透性,研究两株有害真菌粗毒素对甜瓜幼苗的化感作用;根据形态学特征及ITS序列分析对两株有害真菌进行初步鉴定.结果表明:两株有害真菌TF和HF粗毒素对甜瓜种子萌发以及胚轴、胚根生长具有抑制作用,可导致甜瓜幼苗根系丙二醛(MDA)含量、可溶性蛋白含量及细胞膜相对透性增加,其中TF粗毒素原液处理下甜瓜幼苗根系MDA含量和细胞膜相对透性较对照分别增加108.6％和40.6％.两株有害真菌粗毒素可提高甜瓜幼苗根系保护性诱导酶活性,其中,TT粗毒素10倍稀释液处理下根系苯丙氨酸解氨酶(PAL)和过氧化物酶(POD)活性较对照分别增加25.6％和23.2％;HF粗毒素原液处理下根系PAL活性较对照提高30.0％.两株有害真菌TF和HF初步鉴定为木贼镰孢菌(Fusarium equiseti)和层出镰孢菌(F.proliferatum).两株镰孢菌虽然不能通过回接侵染甜瓜,但能通过分泌毒素影响甜瓜正常生长和生理生化代谢,同时提高甜瓜根系保护性诱导酶活性,具有有害和有益双重作用,其化感危害是引起甜瓜连作障碍的主要原因之一.     

不同植物对小麦、黄瓜和萝卜幼苗化感作用潜力的初步评价

以小麦、黄瓜、萝卜为受体植物,用室内和田间生物测定方法,研究了甘肃省农区18种植物的化感作用.结果表明,黄花蒿、龙葵、曼陀罗植株茎叶的水抽提物对3种受体植物化感作用最强,其抑制综合效应(SE)分别为47.66%、32.89%和26.63%;其次是苍耳、马齿苋、刺儿菜、灰藜;其SE值分别为21.71%、20.93%、20.83%、20.2%.对受体植物化感作用较弱的是野豌豆(SE-3.5%)、狗尾草(SE2.2%)、鹅绒藤(SE1.97%);土荆芥(SE-103%)、丛枝蓼(SE-163%)、燕麦(SE-533%)对受体植物无明显化感作用.黄花蒿对受体萝卜、黄瓜、小麦、玉米的苗高、植株鲜重有显著影响,其SE值分别为54.07%、38.46%、33.35%、20.88%;黄花蒿对田间小麦植株生长抑制的综合效应为44.70%.可见黄花蒿具有一定的开发利用价值     

二斑叶螨取食抗、感螨木薯品种对茉莉酸信号途径基因表达的影响

明确二斑叶螨取食影响木薯茉莉酸信号途径基因表达的害螨密度和取食时间效应,为阐明茉莉酸信号途径在木薯抗虫性中的重要作用及抗螨种质资源鉴定评价提供理论依据及参考指标。以抗螨木薯品种C1115和感螨木薯品种面包为材料,分析与植物防御相关的茉莉酸号信号途径基因(DAD1、LOX2、OPR3和JAR1)在二斑叶螨以不同虫口密度(15、25、35、45、50和55头螨/叶)取食不同时间(1、2、4和8 d)后的表达量变化情况。结果表明,以45-50头螨/叶的害螨密度分别取食抗、感螨木薯品种2 d后,LOX2、OPR3和JAR1的表达量均较螨害前显著提高,并且上述3个基因在抗螨木薯品种中的表达量显著高于感螨木薯品种,而DAD1的表达量随害螨密度的提高和取食时间的增加波动较大。在较高的害螨密度和较短的为害时间处理时,茉莉酸信号途径基因LOX2、OPR3和JAR1在抗螨木薯品种中的表达量显著高于感螨木薯品种,LOX2、OPR3和JAR1可能与木薯对二斑叶螨的抗性有关。     

梨黑星菌粗毒素对抗病和感病梨离体叶片生理特性的影响

以不同抗病性梨品种为材料,研究了梨黑星菌粗毒素对梨离体叶片的过氧化物酶(POD)活性、苯丙氨酸解氨酶(PAL)活性、丙二醛(MDA)含量、细胞膜相对透性以及叶绿素含量变化的影响.研究表明,毒素接种后抗病和感病品种叶片的POD和PAL活性、MDA含量和相对电导率均呈上升趋势,其间会有1个或2个峰值出现,且抗病品种叶片的POD和PAL活性高于感病品种,而细胞内MDA含量和相对电导率增加比率低于感病品种;同时,毒素使梨离体叶片的叶绿素、类胡萝卜素含量下降,且感病品种的下降幅度大于抗病品种.总之,梨离体叶片POD和PAL的活性变化与梨品种抗病性呈正相关,叶片MDA含量和相对电导率变化与梨品种抗病性呈负相关,抗病品种离体叶片对毒素的毒害有更强的抵抗力.     

应用PCR-RFLP和巢式PCR检测黄瓜尖镰孢菌

以3株黄瓜尖镰孢菌(Fusarium oxysporum f.sp.cucumarinum)、23株镰孢菌属(Fusariumspp.)真菌和分离自土壤的20株真菌、6株细菌和7株放线菌为材料,采用化学裂解法提取总DNA,进行PCR-RFLP和巢式PCR检测,试验证明PCR-RFLP程序不能完全区分Fusarium属内不同种,而巢式PCR对黄瓜尖镰孢菌具有特异性.运用优化的PCR-RFLP和巢式PCR检测程序对染病黄瓜组织进行了检测,结果表明,两种方法均可在接种发病早期(未显症时)检测出黄瓜枯萎病菌,PCR-RFLP在感病品种接种后3d即可检测到病原菌,而巢式PCR在接种后5d才能检测到病原菌.     

Corynespora cassiicola leaf spot of pawpaw (Carica papaya L.) in Nigeria

Leaf spot of pawpaw is hereby reported for the first time in Nigeria. The symptom is characterized by a papery center surrounded by a yellow halo. The causal organism is Corynespora cassiicola. Ripe fruits and abaxial surfaces of the leaves were significantly more susceptible to infection than unripe fruits and adaxial surfaces of leaves. Growth and sporulation of the fungus on several media was investigated. The organism grew faster on malt-extract agar (MEA) derived media and slowest on potato-dextrose agar (PDA) supplemented with thiamine. Sporulation was highest on Czapek-dox agar (CDA) plus biotin and lowest on PDA and PDA + thiamine. Reasons for increased susceptibility of ripe fruit are discussed.This revised version was published online in October 2005 with corrections to the Cover Date.     

分离自黄瓜的多主棒孢霉不同表型菌株对杀菌剂的敏感性

【目的】通过对分离自黄瓜的多主棒孢霉不同表型菌株适宜生长温度、产孢量等表型特征和对8种杀菌剂的敏感性研究,为多主棒孢霉侵染引起的黄瓜叶斑病和茎疫病的化学防治提供技术支持。【方法】采用温度梯度法测定病菌适宜生长温度;采用PDA培养基25°C黑暗培养5 d和21 d,计测不同表型菌株单位面积产孢量;采用含药平板法测定不同表型菌株对8种杀菌剂的敏感性。【结果】分离自黄瓜的多主棒孢霉不同表型菌株适宜生长温度为25-30°C;在PDA平板25°C黑暗培养5 d,气生菌丝稀少型菌株cu-4、cu-5即大量产孢,产孢量明显多于气生菌丝丰茂型菌株;在试验浓度下,5个试验菌株对8种杀菌剂的敏感性依次为:代森锰锌氟硅唑戊唑醇苯醚甲环唑速克灵百菌清嘧菌酯多菌灵。【结论】分离自黄瓜的多主棒孢霉不同表型菌株在适宜生长温度、菌丝生长速度、产孢量及对杀菌剂的敏感性等方面均存在差异。在试验浓度下,供试菌株对多菌灵和嘧菌酯的敏感性极低(抑制率40%),这2种杀菌剂已失去对该地区黄瓜褐斑病的防控作用。     

Target leaf spot of tomato incited by Corynespora cassiicola,an emerging disease in tomato production under Gangetic alluvial region of West Bengal,India

Abstract

Tomato (Lycopersicon esculentum Mill.) is a cosmopolitan vegetable and widely cultivated in almost all the countries of the world including India. Irreversible investment – production ratio for tomato cultivation in recent Indian agricultural systems arise the question, is there any biotic backlogs responsible for such a production loss. Our present investigation is based on this fact. Target leaf spot disease of tomato is caused by Corynespora cassiicola, a serious and emerging disease in India. Prolonged real time surveillance of this disease on tomato from 2010–11 to 2016–17, reflects some remarkable features of pathogenic progress in Gangetic alluvial region of West Bengal. This pathogen is the natural barrier for tomato production with a disease severity ranged between 35% and 58% which ultimately causes tremendous loss of tomato foliage and fruits. C. cassiicola was identified on the basis of morpho-cultural (ITCC Accession No. 7542) and molecular characterization (Genbank Accession No. KJ767193). Homology searching of internal transcribed spacer region of CcHaTom isolate was highly matched with Genbank Accession No. KP666184 (Cynodondactylon/India), AB873045 (Vitex negundo/India) and JN541214 (Malvaviscus concinnus/USA) with 95% similarity. Phylogenetic analysis established that KJ767193 and C. cassiicola retrieved sequences were conspecific from a common ancestral origin, which supports its neighbourhood with this fungal pathogen. Optimum temperature between 24 and 25?°C, coupled with 80–85% relative humidity triggered the disease progress. From the emerging scenario, C. cassiicola infecting tomato is the real threat for indigenous cultivars.     

Comparative Proteomic Profiling of Methicillin‐Susceptible and Resistant Staphylococcus aureus

Staphylococcus aureus is a highly successful human pathogen responsible for a wide range of infections. This study provides insights into the virulence, pathogenicity, and antimicrobial resistance determinants of methicillin‐susceptible and methicillin‐resistant S. aureus (MSSA; MRSA) recovered from non‐healthcare environments. Three environmental MSSA and three environmental MRSA are selected for proteomic profiling using isobaric tag for relative and absolute quantitation tandem mass spectrometry (iTRAQ MS/MS). Gene Ontology annotation and Kyoto Encyclopedia of Genes and Genomes pathway annotation are applied to interpret the functions of the proteins detected. 792 proteins are identified in MSSA and MRSA. Comparative analysis of MRSA and MSSA reveals that 8 of out 792 proteins are upregulated and 156 are downregulated. Proteins that have differences in abundance are predominantly involved in catalytic and binding activity. Among 164 differently abundant proteins, 29 are involved in pathogenesis, antimicrobial resistance, stress response, mismatch repair, and cell wall synthesis. Twenty‐two proteins associated with pathogenicity including SPA, SBI, CLFA, and DLT are upregulated in MRSA. Moreover, the upregulated pathogenic protein ENTC2 in MSSA is determined to be a super antigen, potentially capable of triggering toxic shock syndrome in the host. Enhanced pathogenicity, antimicrobial resistance, and stress response are observed in MRSA compared to MSSA.     

Suppression by Red Light Irradiation of Corynespora Leaf Spot of Cucumber Caused by Corynespora cassiicola

The effect of red light irradiation on development of Corynespora leaf spot of cucumber plants (Cucumis sativus L. cv. Hokushin) caused by Corynespora cassiicola (Berk. & Court.) was investigated in greenhouses. In a greenhouse without red light (?Red), lesions enlarged, coalesced, and finally covered the entire leaves of cucumber. In a greenhouse with red light (+Red), however, lesion appearance was delayed relative to that under ?Red and its development was also significantly suppressed. Such difference in disease development was also observed in cucumbers grown under +Red and ?Red in the same greenhouse. Disease suppression under red light was also observed in glasshouse‐grown C. cassiicola‐inoculated cucumbers. Red light did not inhibit the infection behaviour of the pathogen. Our results indicated that the delay and suppression of Corynespora leaf spot of cucumber under +Red were due to induction of resistance in cucumber, and not to differences in environmental conditions or fungal population between the two greenhouses. Red light‐induced resistance might contribute to the development of new methods for controlling Corynespora leaf spot of greenhouse‐grown cucumber.     

Histopathology of Sclerotinia Sclerotiorum Attack on Flower Parts of Helianthus Annuus heads in Tolerant and Susceptible Varieties

Sunflower head rot is a major disease caused by Sclerotinia sclerotiorum. Sunflower varieties which are tolerant to the fungus have been developed. The changes occurring in flower parts at different times after inoculation with pathogen ascospores were studied for two sunflower varieties (tolerant HA 302 and susceptible HA 89). In variety HA 302 there was cell collapse, changes in cell wall composition, and an increase in phenolic compounds in the tissues of corolla and style, which prevented the pathogen from advancing. This response was weaker in susceptible variety HA 89, and occurred only in the style, so did not stop the pathogen from developing and reaching the ovary. Phenolic compounds were found in HA 302 corolla and style tissues only when the pathogen was present, constituted an induced response that prevented further development of the fungus. Principal component analysis (PCA) showed that at the beginning of the infection there was no difference in behavior between the two varieties. The difference arose during the final observation times, when in variety HA 89, the pathogen colonized ovary, style and base of filaments and produced noticeable colonization of the corolla.     

不同抗、感水稻品种对褐飞虱肠道菌群的影响

本研究旨在探究取食不同抗性水稻品种对褐飞虱肠道菌群多样性及丰度的影响.将生长一致的3龄褐飞虱若虫分别置于高抗水稻品种RHT、高感水稻品种TN1以及中等抗性水稻品种ZH11,取食1d和3d后,分别对褐飞虱肠道进行取样,提取总DNA并通过HiSeq 2500平台对肠道细菌16S rRNA-V4区进行测序.对测序结果进行分析...     

黄萎病菌粗毒素接种对感病和抗病茄子品种的一些酶类活性和光合特性的影响

以黄萎病菌粗毒素接种不同茄子品种的结果表明:接种后抗病品种比感病品种的过氧化物酶(POD)、超氧化物歧化酶(SOD)活性高,而多酚氧化酶(PPO)和苯丙氨酸解氨酶(PAL)活性则相对稳定;前者叶的净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)和细胞间CO2浓度(Ci)的变化幅度比后者小,但72 h后二者的叶片Pn、Gs、Tr都明显呈下降趋势.