假单胞菌对香蕉枯萎病菌的抑制作用

从已感染香蕉枯萎病的果园中分离到1株对香蕉枯萎病菌（Fusarium oxysporum f.sp.cubense）抑制作用很好的菌种,命名为G1。采用固体和液体培养法从不同角度证实了G1对香蕉枯萎病菌生长的抑制作用。结果表明,G1的发酵液、无菌滤液、挥发性物质、非挥发性代谢产物的平均抑菌率分别为92.5%、27.4%、73.8%、57.7%,可见抑制作用与活菌体有直接关系,其中产生挥发性物质尤其重要。液体培养的病原菌浓度为1.0×107cfu/mL经G1作用10d后,取样镜检发现G1通过抑制病原菌菌丝正常生长以至不能产孢,从而导致菌丝消融;通过吸附在孢子的周围,融解细胞壁,造成原生质泄露致使孢子死亡。     

香蕉枯萎病菌侵染香蕉根系的组织学过程

 为探明香蕉枯萎病菌侵染香蕉根系的过程,利用绿色荧光蛋白标记的香蕉枯萎病菌4号生理小种（Fusarium oxysporum f. sp. cubense race 4 tagged with green fluorescent protein,GFP-FOC4）,接种香蕉根系以观察病原菌侵染香蕉根系的组织学过程。结果表明,接种1 d后病原菌以菌丝体、大型分生孢子和小型分生孢子的形式附着于根系表皮细胞,优先沿细胞胞间层生长。接种7 d后,观察到病原菌以菌丝体、大型分生孢子和小型分生孢子的形式直接侵染维管束,在维管束内以两种方式扩展繁殖,一种在维管束内横向扩展,菌丝体随机分支,逐步形成网状分布;另一种是菌丝体在维管束内纵向生长,倾向于呈束状沿维管束单侧生长繁殖,形成大量菌丝体。本研究首次从组织病理学的角度观察并分析了GFP-FOC4侵染香蕉根系的过程,为研究香蕉枯萎病菌的致病过程机理提供参考。     

Sensitivity of Fusarium oxysporum f. sp. cubense to phosphonate

Phosphonate (0.1 mM) significantly reduced growth of Fusarium oxysporum f. sp. cubense (Foc) race 4 grown at an optimal phosphate concentration of 0.3 mM in vitro. At higher phosphate concentrations, closer to physiological conditions within the plant, the sensitivity of Foc race 4 to phosphonate was greatly reduced, with 25 mM phosphonate required to reduce growth by 50% at 1 mM phosphate. Two isolates of Fusarium oxysporum f. sp. dianthi and another race of Foc, race 1, were shown to be similar to Foc race 4 in their sensitivity to phosphonate, while another species of Fusarium, F. avenaceum , was more sensitive to phosphonate in vitro.     

Resistance sources to Fusarium oxysporum f. sp. cubense tropical race 4 in banana wild relatives

Target trait evaluation in crop wild relatives is an important prerequisite for efficiently using the potential useful genes located in this valuable germplasm. Over recent decades, Fusarium oxysporum f. sp. cubense tropical race 4 (Foc‐TR4) has seriously threatened worldwide banana plantations. Breeding new resistant cultivars from wild banana species is expected to provide invaluable additional resources. However, knowledge on resistance to Foc‐TR4 in wild Musa species is very limited. In this study, eight genotypes of wild banana relatives (Musa acuminata subsp. burmannica, M. balbisiana, M. basjoo, M. itinerans, M. nagensium, M. ruiliensis, M. velutina and M. yunnanensis) were characterized for resistance to Foc‐TR4 in both greenhouse and field conditions. Most wild bananas showed higher resistance levels to Foc‐TR4 than the reference cultivars ‘Brazilian’ (AAA, susceptible) and ‘Goldfinger’ (AAAB, moderate resistance). Among the wild species, M. balbisiana showed the highest levels of disease intensity followed by M. acuminata subsp. burmannica. Some individuals of M. yunnanensis, M. nagensium, M. ruiliensis and M. velutina showed low levels of rhizome discolouration in greenhouse conditions, but were resistant in the field. No symptoms were observed on M. basjoo and M. itinerans, suggesting higher levels of resistance to Foc‐TR4. The results revealed different sources of resistance to Foc‐TR4 in banana wild relatives, which constitute a valuable genetic resource for banana breeding programmes aiming to produce cultivars resistant to fusarium wilt.     

香蕉枯萎病菌SIX2基因序列及特异性分析

依据侵染的香蕉品种范围不同,引起香蕉枯萎病的尖孢镰刀菌古巴专化型(Fusarium oxysporum f.sp.cubense,Foc)分为4个生理小种。Foc在寄主植物木质部分泌的SIX(secreted in xylem)蛋白可能与不同生理小种侵染的香蕉品种范围不同存在密切关系,找到Foc 4号生理小种(Foc4)特有的SIX蛋白编码基因将有利于进一步分析Foc4寄主范围更广的原因,从而开展抗病育种工作。采用PCR方法比较分析了国内不同地理区域及来源于澳大利亚与南非的Foc1、Foc2、Foc3、Foc4共56株菌株中的SIX2基因,并以8个以上其他专化型或其他种或属的热带作物病原菌共39株菌株分析了Foc4 SIX2基因序列的特异性,分析了SIX2基因的灵敏度及利用其检测感病植株。仅从供试的Foc4菌株基因组DNA中扩增出SIX2基因序列,检测的DNA灵敏度达5pg/25μL,并可用于检测感病的球茎组织。Foc4中特有的SIX2基因序列为特异性鉴定感病植株病原菌种类提供了快速分子检测技术,为明确该基因是否决定性影响Foc4对寄主差异性的选择研究提供了基础。     

香蕉枯萎病菌生理分化研究摘要本研究

本研究对香蕉枯萎病菌菌株FOCAAA9(来自香蕉)和FOCABB1(来自粉蕉)进行培养试验和接种试验;在含粉蕉和香蕉组织浸提液的培养基上2个菌株的培养性状、菌丝生长速度、孢子形态、大小型孢子比率和产孢量显示出差异;接种结果FOCAAA9能侵染香蕉(MusaAAA)品种巴西蕉、红香蕉和台蕉引起枯萎病,而FOCABB1对3个香蕉品种无致病性。研究结果表明侵染香蕉和粉蕉的古巴尖镰孢[Fusariumoxysporumf.sp.cubense(E.F.Smith)Snyder]存在生理分化现象。     

香蕉枯萎病菌生理分化研究

本研究对香蕉枯萎病菌菌株FOCAAA9（来自香蕉）和FOCABB1（来自粉蕉）进行培养试验和接种试验；在含粉蕉和香蕉组织漫提液的培养基上2个菌株的培养性状、菌丝生长速度、孢子形态、大小型孢子比率和产孢量显示出差异；接种结果FOCAAA9能侵染香蕉（Musa AAA）品种巴西蕉、红香蕉和台蕉引起枯萎病，而FOCABB1对3个香蕉品种无致病性。研究结果表明侵染香蕉和粉蕉的古巴尖镰孢[Fusarium oxysporum f．sp．cubeilse（E．F．Smith）Snyder]存在生理分化现象。     

香蕉枯萎病菌RAPD分析及4号生理小种的快速检测

 用随机扩增多态性DNA(RAPD)技术,对采自广东、广西的香蕉和粉蕉上的30个香蕉枯萎病菌(Fusarium oxysporum f.sp.cubense)菌株和3个其它尖孢镰刀菌专化型的菌株进行比较及聚类分析。在遗传相似系数0.67时,可将供试菌株划分为3个RAPD群(RGs),其中香蕉枯萎病菌4号生理小种(FOC4)共15个菌株属于RGⅠ,1号生理小种(FOC1)共15个菌株属于RGⅡ,供试的其它尖孢镰刀菌专化型的3个菌株则属于RGⅢ。这说明香蕉枯萎病菌和供试3个其它专化型菌株与致病性间存在明显的相关性。1号生理小种内菌株间的遗传分化大于4号生理小种内菌株间的遗传分化。从90条RAPD随机引物中筛选出2条引物可产生4号生理小种的RAPD标记2个。将这2个RAPD标记电泳切胶回收、克隆及测序,并根据这2个特异片段序列设计SCAR上下游特异引物,通过对30个菌株的PCR扩增检验,其中一个RAPD标记成功地转化为SCAR标记,初步建立了以此为基础的4号生理小种快速检测技术,其检测灵敏度为2 ng新鲜菌丝。对采自不同地区的显症样品、吸芽、室内接种未显症的香蕉苗以及发病的香蕉植株不同部位进行检测,能够准确灵敏地鉴定出4号生理小种,从而为香蕉枯萎病菌的快速检测及防治奠定了基础。同时,快速检测结果发现,田间发病植株果柄的各部位及果实内并没有枯萎病菌的存在。     

香蕉枯萎病菌生理小种鉴定及其SCAR标记

 通过室内人工接种蕉类鉴别寄主,对采集于广东蕉区的18个蕉类枯萎病菌菌株进行鉴定,KP021、KP022、GZ981和JL021 4个菌株属Racel,其余14个菌株属Race4,说明广东蕉区同时存在尖孢镰刀菌古巴专化型Race1和Race4。用RAPD技术对上述18个菌株进行分析,从200条随机引物中筛选出8条引物可产生生理小种RAPD标记12个,其中标记Racel的8个,标记Race4的4个。对这些RAPD标记带分别进行回收、克隆、测序,根据这些特异片段序列分别设计相应的SCAR引物,通过对18个菌株的PCR扩增检验,有4个RAPD标记成功地转化为SCAR标记,其中Race1-SCAR标记1个、Race4-SCAR标记2个、同时能鉴定出2个小种的SCAR标记1个。应用这4个SCAR标记同时对采自田间的9个病菌分离物进行检测,能够准确地鉴定出广东蕉区的尖孢镰刀菌古巴专化型Racel和Race4,这为下一步开展香蕉枯萎病菌生理小种的分子鉴定及各生理小种田间流行动态监测奠定了基础。     

根癌农杆菌介导的香蕉枯萎病菌4号生理小种的转化

 本文针对香蕉枯萎病菌4号生理小种这一对我国香蕉生产构成了极大威胁的检疫性有害生物,建立了根癌农杆菌介导的该生理小种的转化体系,确定了影响转化效率主要因子的最佳条件分别是:共培养乙酰丁香酮(AS)浓度为200μmol/L、共培养时间为48 h、培养温度为25℃、诱导培养基pH值为5.5。此条件下,转化效率达到21~24个转化子/10⁴香蕉枯萎病菌孢子。PCR和Southern杂交分析表明外源的T-DNA已经成功随机地整合到该病原菌基因组中,且多为单拷贝。应用该转化体系已获得近25 000个转化子,为研究该生理小种致病机制奠定了基础。     

香蕉枯萎病生防菌对杀虫剂的适应性研究

将4株香蕉枯萎病生防细菌bio ZK11、bio HN2、bio HN10和bio F4分别与杀虫剂噻唑磷、毒死蜱、辛硫磷混合,测定其混合液对香蕉枯萎病病菌孢子萌发的抑制作用以及杀虫剂对生防菌生长繁殖的影响。结果显示,噻唑磷对生防菌bio ZK11的抑菌作用没有影响,而毒死蜱和辛硫磷增强bio ZK11的抑菌作用;噻唑磷和毒死蜱增强bio HN2的抑菌作用,辛硫磷则对bio HN2的抑菌作用没有影响;噻唑磷、毒死蜱和辛硫磷增强了生防菌bio HN10的抑菌作用;噻唑磷、毒死蜱和辛硫磷对生防菌bio F4的抑菌作用没有影响。辛硫磷对生防菌bio HN2的菌落生长有一定的影响,对另外3种生防菌没有影响;噻唑磷对4种生防菌菌落大小都没有影响;毒死蜱对香蕉枯萎病生防菌bio HN10的菌落大小没有影响,但使生防菌bio ZK11、bio HN2和bio F4的菌落变小。3种杀虫剂除了对生防菌bio F4的生长量没有显著影响,对其他3种拮抗菌的生长都有一定的影响。     

香蕉枯萎病颉颃放线菌的分离和筛选

从采自内蒙古、海南的土样中经分离、纯化得到64株优势放线菌,采用平板对峙培养法对香蕉枯萎病菌(Fusarium oxysporum f.sp.cubense)进行颉颃放线菌的筛选.通过皿内颉颃试验,获得4株抑菌效果较好的颉颃放线菌,以HN3菌株的抑菌效果最为明显,发酵液抑茵试验表明,其抑菌物质存在于菌丝内.     

香蕉枯萎病菌群体多样性研究进展

香蕉枯萎病严重威胁世界香蕉产业,而目前尚无有效防治药剂。开发快速诊断技术以加强检疫,控制其传播速度,同时加快选育抗病品种是有效控制该病的根本策略。然而,无论是研发快速诊断的分子技术还是进行抗病品种的选育,都需要深入了解病原菌的群体结构及其基因多样性背景。香蕉枯萎病菌经过一个多世纪的变异与进化,已分化出4个生理小种,23个营养亲合群和多个基因多样性类群。本文从香蕉枯萎病的起源及其病原菌培养性状、生理小种、致病性、营养亲合群及基因多样性等方面研究进展进行梳理和分析,以期为下一步的研究提供思路和启发。     

Fusarium Wilt of Banana Is Caused by Several Pathogens Referred to as Fusarium oxysporum f. sp. cubense

ABSTRACT Fusarium wilt of banana (also known as Panama disease) is caused by Fusarium oxysporum f. sp. cubense. Where susceptible cultivars are grown, management is limited to the use of pathogen-free planting stock and clean soils. Resistant genotypes exist for some applications, but resistance is still needed in other situations. Progress has been made with this recalcitrant crop by traditional and nontraditional improvement programs. The disease was first reported in Australia in 1876, but did the greatest damage in export plantations in the western tropics before 1960. A new variant, tropical race 4, threatens the trades that are now based on Cavendish cultivars, and other locally important types such as the plantains. Phylogenetic studies indicate that F. oxysporum f. sp. cubense had several independent evolutionary origins. The significance of these results and the future impact of this disease are discussed.     

FoAP1基因在香蕉枯萎病菌致病过程中的功能分析

 为了探究AP1转录因子在尖孢镰刀菌古巴专化型4号生理小种(Foc4)中是否参与香蕉枯萎病的致病过程,借助尖孢镰刀菌Fo5176菌株(GenBank序列号:AFQF01001482.1)全基因组序列,通过PCR和RT-PCR技术克隆获得了Foc4中AP1转录因子的基因组DNA和cDNA编码序列.利用PEG介导的原生质体转化法获得AP1基因敲除转化子。利用qRT-PCR分析AP1可能调控的下游基因表达。利用灌根法(直接在根部浇菌)检测了AP1缺失突变体的致病能力。结果表明Foc4的AP1转录因子cDNA编码序列长1770bp,编码63.9kDa(589aa)蛋白,是一个典型的bZIP型转录因子,命名为FoAP1;FoAP1缺失突变体的气生菌丝大量减少,菌丝的入侵生长受到严重限制。对外源氧化胁迫不敏感,但致病能力减弱。     

Evaluating the potential of soil management to reduce the effect of Fusarium oxysporum f. sp. cubense in banana (Musa AAA)

European Journal of Plant Pathology - Fusarium oxysporum f. sp. cubense (Foc) causes Fusarium wilt in banana (Musa AAA). Foc Race 1 devastated the subgroup Gros Michel during the first half of the...     

Genetic structure of Fusarium oxysporum f. sp. cubense in different regions from Brazil

Panama disease, caused by Fusarium oxysporum f. sp. cubense (Foc), is ranked among the most destructive diseases of banana. The use of resistant varieties is the most desirable and effective control measure. Information on the pathogen population structure is essential, as durability of the resistance and effective cultivar deployment are strongly linked to this structure. In this study, 214 Foc isolates from different banana producing states in three regions of Brazil (northeastern, southeastern and southern) were analysed. Initially, nine microsatellite markers (SSR) were tested, which revealed 52 distinct haplotypes distributed in the different geographical regions and cultivars. While amova analysis showed that 68·01% of the total variation occurred within states, correlation between genetic and geographical distances was only found in the southern region. Results indicated that isolates from different states comprise a single population, which is predominantly clonal. When isolates representing different haplotypes were inoculated in four banana cultivars, differences in severity were found, with the high severity values being caused by isolates from haplotypes H7, H31 and H41. The diversity found here points to the need for additional studies, as this characteristic may be related to Foc's evolutionary potential and possibly to its ability to overcome the resistance from breeding programme‐generated cultivars. This is the most comprehensive study on population biology of Foc in Brazil.     

香蕉枯萎病生防细菌的筛选、鉴定及其抑菌作用

采用平板对峙法,从香蕉根部土样中分离到1株枯萎病拮抗芽孢杆菌XY-10。根据形态特征及16S rDNA分析将其鉴定为多粘类芽孢杆菌Paenibacillus polymyxa。拮抗试验表明菌株XY-10不同浓度的发酵滤液均可抑制病原菌孢子萌发和生长,当发酵滤液浓度分别为10%、30%和50%时,其在高度抑制水平上的抑制率分别为7%、23%和40%。经发酵滤液处理,病原菌菌丝末端膨大成球状、菌丝破裂、消解,菌丝体分枝增多。