豇豆贮藏期软腐病病原菌鉴定及其生物学特性研究

豇豆是海南最主要的冬季瓜菜之一。2019年,调查发现豇豆贮运期间出现一种严重的软腐病。通过病原菌分离、致病性测定、形态学观察和分子生物学鉴定,鉴定该病原菌为瓜果腐霉[Pythium aphanidermatum (Edson) Fitzp.]。采用生长速率法对该病原菌生物学特性进行初步研究。结果表明：该菌菌落适宜生长温度范围为30~35 ℃,最适生长温度为35 ℃,菌落致死温度为50 ℃、10 min;适宜生长的pH为7.0~9.0,最适pH为9.0;最适碳源为可溶性淀粉;最适氮源为蛋白胨;不同光照条件对菌落生长没有显著影响。本研究首次报道瓜果腐霉（P. aphanidermatum）引起豇豆的采后病害。     

科技前沿摘编

选择被认为对水淹有较好抗性的6个大豆基因型品种，检测其在洪水灾害下土传真菌对大豆的作用。试验在1996年到1998年进行，6个基因型大豆进行垄上单行种植，设置不同水淹处理，分别为无水淹、出苗时水淹（持续3d）和第四个叶节期水淹（持续7d）。在水淹处理3~4d后，统计出苗率，并在每个小区采集15株大豆样本，进行称重，并调查根部褪色比率，分离鉴定根上真菌及其他丝状微生物。试验结果显示，与无淹水相比在出苗期淹水导致出苗率降低。与无水淹处理相比，在大豆生长期2个水淹处理的大豆根部褪色比率明显增加，而植株重量明显降低。在水淹处理中分到的丝状真菌，只有腐霉属（Pythium）真菌分离频率明显增加，依据腐霉菌在PDA、CMA和V8培养基上的菌落形态以及生长速度进行种的鉴定，并用60个腐霉菌菌株对大豆进行致病性测定，结果显示，其中有47%的腐霉菌菌株对大豆有较高的致病性。分离自大豆的致病腐霉菌种类包括：终极腐霉（P. ultimum）、瓜果腐霉（P. phanidermatum）、畸雌腐霉（P. irregulare）和钟器腐霉（P. vexans），另外也分离到了对大豆非致病性菌寡雄腐霉（P. vexans）。     

海南白蚁共附生放线菌的分离鉴定及其抗热带作物病原真菌活性研究

白蚁（Isoptera）的筑巢和觅食活动主要在土壤及腐烂的木材上进行,所以白蚁极易受到来自环境病原微生物的侵害。因此,白蚁需要依赖共附生微生物菌群形成防御体系,放线菌是其中一个重要的类群,且放线菌能产生具有抗菌活性的次级代谢产物。但是白蚁共附生放线菌能否对热带作物的病原真菌有抑制活性有待研究。为了挖掘在热带农业绿色健康发展中具有应用潜力的海南特色农用放线菌资源,以海南白蚁共生放线菌为研究对象,利用平板分离法从采集的健康白蚁体内分离纯化放线菌,利用平板对峙法筛选生防菌株;通过分子生物学确定其分类地位;平板对峙法研究拮抗菌株的抗菌稳定性、持效性和广谱性;滤纸片法研究抑菌物质的热稳定性。结果从海南白蚁体内分离得到1株拮抗活性较好的放线菌菌株W7,系统发育树分析结果表明该放线菌与链霉菌属（Streptomyces）亲缘关系接近。菌株W7的抗菌活性持久性强,平板接种30 d后仍对植物病原真菌具有抑菌活性,抗菌稳定性好;菌株W7抑菌谱广,对16株植物病原真菌有不同程度的抑菌活性,其中对芒果胶孢霉（Colletotrichum gloeosporioides Penz.）、香蕉炭疽霉（Colletotrichum musae）、辣椒棒孢霉（Corynespora cassiicola）、豇豆瓜果腐霉[Pythium aphanidermatum (Edson) Fitzp]抑制作用较强,对芦笋拟茎点霉（Phomopsis asparagi）、荔枝疫霉（Peronophythora litchi）抑制作用较弱;菌株W7发酵粗提物有较好的热稳定性,但是抑菌率会随着水浴温度的增高而降低。本文首次对海南白蚁共附生放线菌进行了分离鉴定,并从中筛选得到1株具有抑制多种热带作物病原真菌活性的生防菌株,为高效生防菌剂的研发提供新资源。     

2009年黑龙江省大豆新品系抗疫霉根腐病鉴定与评价

通过对21个大豆疫霉根腐病菌株进行鉴定,共鉴定出6个生理小种,即1、3、9、11、17、21号生理小种,其中54%的菌株为1号生理小种,表明1号生理小种仍是黑龙江省的优势生理小种.同时对346份黑龙江省大豆种质进行了大豆疫霉根腐病的抗病性鉴定与评价,鉴定出抗疫霉根腐病的资源15份,占供试材料的4.3%;中抗材料12份,占供试材料的3.5%;其它材料均为感病,占供试材料的92.2%.结果表明黑龙江省大豆疫霉根腐病抗性资源较少.     

黑龙江省大豆疫霉根腐病菌毒力类型分布及品种抗性评价

对2008～2009年从黑龙江北部、东部、中部、南部等大豆产区采集的典型大豆疫霉根腐病株和病土进行分离纯化,得到64个大豆疫霉菌株;用国际上通用的一套鉴别寄主进行毒力测定,将病原菌划分为10个毒力类型,在不同来源的发病样本范围内明确了不同菌株的毒力类型和分布.用下胚轴创伤接种方法鉴定了73个大豆品种对不同大豆疫霉根腐病菌菌株的抗性反应,结果有29个品种抗4个以上大豆疫霉根腐病菌株,占鉴定总数的39.7%;在被鉴定的新品系中抗性表现最好的是07-1-1,它对1、3、11、21、24分离物均表现为抗病.     

大豆种质对大豆疫霉菌株Pm8的抗性分析

采用黄化苗下胚轴接种法,利用大豆疫霉菌株Pm8对来自不同地区的355份大豆品种(系)进行疫霉根腐病接种鉴定。结果表明:96份材料表现为抗病类型,占鉴定总数的27%,106份表现为中间类型,占总数的30%。在所鉴定的品种(系)中,北京、浙江等省(市)抗大豆疫霉菌株Pm8的资源比较丰富;吉林、四川等省的抗性资源较贫乏。研究结果为大豆抗病育种选择亲本和利用品种布局进行大豆疫霉根腐病生态控制提供了依据。     

大豆接种疫霉根腐病菌后过氧化物酶活性的变化

通过分析不同抗性大豆品种接种疫霉根腐病菌l号生理小种后，根、茎、叶中过氧化物酶(POD)活性变化的规律，探讨了过氧化物酶在大豆抗疫霉根腐病中的作用。研究结果表明：抗感品种接种疫霉根腐病1号生理小种后，同一品种不同部位POD活性变化是不相同的，通过不同部位之间POD活性的变化来共同完成抵抗病原菌侵害的过程。大豆接种疫霉根腐病菌后过氧化物酶活性的变化，不宜作为一种生化指标来鉴定品种对疫霉根腐病的抗性。     

筛选用于防治大豆尖孢镰刀菌根腐病的木霉菌株

采用平板对峙培养、温室盆栽的方法筛选来自黑龙江省海伦大豆轮作区的木霉菌,用于防治大豆尖孢镰刀菌根腐病.共测试了80个木霉菌株,筛选出3个防治效果较好的木霉菌株MM35、MM9、MM3 ,相对防效分别为26.95%～66.34%、21.52%～63.70%、22.78%～51.05%.盆栽试验表明MM35能够降低大豆根腐病的主要病原菌-尖孢镰刀菌(Fusarium oxysporum)在土壤中的种群数目.其中MM9对大豆植株能起到增生作用,MM35、MM3则无明显的促生作用.     

伯克氏菌对群结腐霉引起的花生果腐病的生防潜力（英文）

花生果腐病是一种世界性的花生病害，群结腐霉是其主要致病菌之一，在花生生产过程中造成重大经济损失，生物防治是一种有效的绿色防控手段。为了控制花生果腐病的发生，从健康的花生植株上分离获得39株内生细菌，并筛选出5株对群结腐霉菌具有明显拮抗活性的菌株。结果表明，基于16S核糖体RNA序列和RecA序列，有5个菌株均被鉴定为洋葱伯克霍尔德菌(Burkholderia cepacia),其中，菌株PRI08对群结腐霉菌菌丝生长显示出较强的拮抗活性。通过温室和田间试验，接种洋葱伯克霍尔德菌PRI08后，再用群结腐霉侵染花生植株，发病率分别降低了29.5%和11.83%。此外，洋葱伯克霍尔德菌PRI08对花生有明显的促生作用，增加主茎高、侧枝长、荚果数量、饱果率和荚果产量，分别为20.44%,19.98%,26.61%,20.36%和21.52%。本研究表明，洋葱伯克霍尔德菌PRI08具有作为花生果腐病生物防治剂和花生生长促进菌的潜力。     

大豆品种对四种腐霉菌的抗性研究

采用种子腐烂测试法,用对大豆有致病性的4种腐霉菌对83个大豆栽培品种进行抗性鉴定.在参试材料中,有抗1种腐霉菌的材料,也有同时抗两2种以上腐霉菌的品种,并获得4个对4种腐霉菌都具有抗性的品种;对于单个腐霉菌而言,抗性材料数量不同.对于P.aphanidermatum表现抗性的材料有19个,占供试材料的22.3%;对P.sylvaticun表现为高抗的材料有34份,占供试材料的41.0%;对P.irregulare表现为高抗的材料有12份,占供试材料的14.5%;对P.ultimum表现为高抗的材料有32份,占供试材料的38.6%.在参试品种中,以抗P.sylvaticun和P.ultimum的材料较多,有20个品种,占参试品种的24.1%,这表明在现有大豆品种资源中有较丰富的抗源.     

Effect of pythium root rot on yield of white bean, Phaseolus vulgaris L.

The effects of Pythium paroecandrum and P. ‘spherical’ on seed yield of white bean (Phaseolus vulgaris L.) were determined under field conditions. Fenaminosulf (Lesan) applied as a soil drench selectively suppressed Pythium populations in soil and increased seed yields by 47% in 1976 and by 33% in 1977. Fumigation of soil with DD-MIT (Vorlex), a commercial mixture of methyl isothiocyanate, dichloropropenes and dichloropropanes, reduced populations of Pythium and Fusarium in soil and increased seed yields by 79% in 1976 and by 29% in 1977. The combination of fenaminosulf and DD-MIT produced the greatest reductions in soil populations of Pythium and Fusarium and increased seed yields by 65%. Pythium paroecandrum and P. ‘spherical’ were associated with feeder-root necrosis and were the only bean-root pathogens detected at the experimental site. In this study, losses in seed yield of white bean due to Pythium root rot were estimated to be 44% in 1976 and 39% in 1977.     

Efficacy of biocontrol agents in planting mixes to colonize plant roots and control root diseases of vegetables and citrus

Tomato, bell pepper, celery and citrus were propagated in planting mixes amended with formulations of commercial biocontrol agents. Root colonization by selected biocontrol agents was evaluated for pepper, tomato and citrus, and found to be generally between 76 to 100% in both greenhouse ebb and flow, and bench-produced plants. Only colonization by Glomus intraradices was low, about 8%. All biological control agents, Trichoderma harzianum, Bacillus subtilis, G. intraradices, Gliocladium virens, and Streptomyces griseovirdis reduced crown rot of tomato in the field, with T. harzianum and B. subtilis being the most effective uniformly among four tests. Four biocontrols reduced Phytophthora root rot on citrus in the field, two applied as a drench to soil in pots reduced Thielaviopsis root rot on citrus, and two biocontrol agents in combination reduced celery root rot caused by Pythium and Fusarium spp., however, none improved above-ground plant growth or health of citrus and celery. Pepper crown and root rot caused by P. capsici was reduced by B. subtilis in one of two tests.     

Field tests of Trichoderma harzianum Rifai aggr. as a biocontrol agent of seedling disease in several crops and Rhizoctonia root rot of sugar beet

In field studies, mean stands of crops of snapbean, field corn, pea, soybean, and squash in New York were somewhat greater from seeds treated with conidia of Trichoderma harzianum applied in a Methocel slurry than from non-treated controls; however, stands were generally poorer than those from captan-treated seed. The biocontrol agent and captan had little effect on kidney bean and sweet corn since these crops are only slightly susceptible to seedling disease caused by Pythium spp. which were present in the field. In Colorado fields also infested with Pythium spp., stands of sugar beet from T. harzianum-treated seed (Pelgel slurry) tended to be greater than those from non-treated seed and equal to those from maneb-treated seed, but differences were not significant. In Colorado, Rhizoctonia solani, cause of root rot, was also present in the soil. A combined analysis of variance of treatments across 2 years showed that a preplanting-incorporated in-row application of T. harzianum in a wheat-bran carrier or a maneb seed treatment slightly, but significantly, reduced the severity of Rhizoctonia root rot in sugar beet as compared with the non-treated control. Seed treatments with T. harzianum had little or no effect. In plots where the agent was applied to the soil, numbers of Trichoderma propagules increased 600-fold by harvest; where maneb seed treatment was used, they increased only fivefold. Densities of the agent remained the same or decreased in plots where Trichoderma was used as a seed treatment.     

油梨根腐病病原菌的鉴定、生物学特性及室内药剂筛选

根腐病是油梨的毁灭性病害之一,该病害为害根部,引起根部变黑腐烂,严重时导致植株死亡。从发病典型的植株根部分离、纯化菌株,并开展致病性测定、形态学特征和多基因位点（ITS、LSU和COXⅡ）系统发育树分析相结合的病原菌鉴定。结果表明,引起海南油梨根腐病的病原菌为樟疫霉（Phytophthora cinnamomi）。还研究了不同培养条件和10种药剂对病原菌菌丝生长的影响。结果表明,病原菌在PDA培养基上生长较好,最适生长温度为28 ℃,最适pH为8,黑暗条件更适合病原菌的生长;烯酰吗啉对病原菌的抑制作用最强,EC₅₀为0.0929 μg/mL。本研究结果为油梨根腐病的田间防控提供了一定的理论依据。     

New sources of resistance to Phytophthora megakarya identified in wild cocoa tree populations of French Guiana

Cocoa black pod rot, a disease caused by oomycetes of the genus Phytophthora, causes substantial yield losses throughout the world, particularly in Africa with the very aggressive species Phytophthora megakarya. In order to reduce the impact of that pathogen, priority is given to genetic control through more resistant cultivars, and breeders are seeking sources of resistance in wild cocoa trees. Wild cocoa trees were surveyed in French Guiana between 1985 and 1995, leading to the collection of abundant plant material from more than 200 mother trees originating from five river basins. We present here the results of tests to assess resistance to the species P. megakarya (a species only existing in Africa), conducted at CIRAD in Montpellier, France, on circa 40 genotypes collected in the Camopi river basin, along with approximately 20 genotypes from other populations (Kérindioutou, Borne 7, Euleupousing, Pina and Oyapok). The strain used for artificial inoculation was NS269, isolated in Cameroon. Seven cacao clones were classified as “highly resistant” and 29 as “resistant”, some of which displayed greater resistance to P. megakarya than the reference resistant clone IMC 47. This study suggests that the wild material from French Guiana could play a significant role in controlling P. megakarya in Africa and also Phytophthora palmivora in all cocoa-producing zones.     

大豆根腐病的研究

大豆根腐病病原物的分离鉴定结果表明,病原菌为Fusarium solani(Mart.)Sacc和Fusarium oxysporum var.redoles(Wollenw、)Gordon。前者除危害根和茎基部皮层外,还可侵入植株中下部维管束,引起萎蔫。后者仅引起根腐,严重时植株枯死。病田种子不带菌,病田土壤和病残体是该病侵染源。粘质土壤较砂质土壤发病重。大豆品种间的抗病性差异显著。     

大豆根腐病的发生及其综合防治策略

系统地介绍了大豆根腐病的发生及病原菌病害综合防治,明确了该病的发生与品种、土壤类型及气象等诸方面的关系,为病害的防治提供了理论依据,证明了带菌土壤和种子是该病害主要侵染和传播途径,同时建立了综合防治体系。     

大豆对疫霉根腐病抗病性鉴定方法

应用下胚轴伤口接种方法鉴定８５份大豆种质对大豆疫霉菌１号生理小种的抗病性,在两次鉴定中有９５．２９％的大豆品种（系）表现一致的抗病或感病反应。本方法所获鉴定结果稳定可靠,利用注射器接种可以极大地提高工作效率,建议作为我国鉴定大豆种质资源对大豆疫霉根腐病抗病性的基本方法。     

广东花生黑腐病病原菌鉴定及防治药剂的室内毒力测定

花生黑腐病是花生的重要病害,对生产造成严重影响,被列为我国进境植物检疫性病害。为明确花生黑腐病的病原菌种类和筛选有效防治药剂,采用形态学特征与分子生物学技术相结合的方法,对花生黑腐病害进行了病原菌鉴定,同时采用菌丝生长速率法测定了8种杀菌剂对花生黑腐病菌的抑制作用。结果表明：花生黑腐病害的病原菌为冬青丽赤壳Calonectria iliciola。8种杀菌剂室内毒力测定结果显示,10%戊唑醇EC对花生黑腐病菌的毒力最强,EC₅₀值为1.12 μg/mL;300 g/L苯甲·丙环唑EC、29%吡萘嘧菌酯SC、25%咯菌腈SC、15%吡唑嘧菌酯SC和22.5%啶氧菌酯SC对花生黑腐病菌也有较好的抑制作用,EC₅₀均低于10 μg/mL;30%精甲恶霉灵的抑制作用最差,EC₅₀值为76.71 μg/mL。以上研究结果可为花生黑腐病的防治提供理论依据。