椰子平脐蠕孢叶斑病病原鉴定及生物学特性测定

2012年10月,在海南省文昌市的椰子苗圃中,发现了一种新的叶斑病。显微观察表明,病原菌分生孢子稍弯曲,浅褐色,纺锤状或梭状,具有5~9个假隔膜、分生孢子梗多单生,直立或稍弯曲,表明其为平脐蠕孢属(Bipolari.sp)。ITS序列分析表明其和4株狗尾草平脐蠕孢的序列同源性(HE792936.1,JX462256,GUO73108.1,FJ606786.1)的同源性为99%。生物学特性研究结果表明:该菌菌丝适宜生长温度为20~30℃,菌丝生长和孢子最适萌发温度分别是25℃和30℃;最适p H值为4~11;玉米粉培养基(CAM)及马铃薯葡萄糖琼脂培养基(PDA)最适合菌丝生长,最佳碳源为蔗糖,甘油不适合菌丝生长;最佳氮源为蛋白胨,其次是磷酸氢二铵;完全光照有利于菌丝生长。菌丝及分生孢子的致死温度和时间分别是56℃,15 min。     

甘蔗环斑病菌鉴定及其生物学特性分析

甘蔗环斑病是甘蔗较为常见的一种真菌性病害。针对海南昌江十月田甘蔗种植地出现一种严重危害疑似环斑病的叶斑病,本文通过对其病原菌的形态学特征观察,并结合ITS序列系统聚类分析,将叶斑病病菌鉴定为引起环斑病的甘蔗小球腔菌Leptosphaeria sacchari。生物学特性分析结果表明:适宜该菌生长的温度为13~30℃,最适温度为25℃;适宜菌丝体生长的p H为4~11,最适p H为5,全黑暗有利于菌丝体的生长;适宜生长的碳源为麦芽糖和葡萄糖、氮源为硝酸钠和L-丝氨酸。采用生长速率法对6种杀菌剂敏感性进行了测定,结果揭示咪鲜胺、丙环唑、多菌灵、腈菌唑等4种药剂对甘蔗环斑病菌具有显著的抑制效果,其EC50值分别为0.397 6、2.251 9、2.163 4、4.827 3μg/m L。     

辣椒新叶斑病病原鉴定及其生物学特性

2015—2019年,笔者在对海南地区的辣椒病害进行调查时,发现一种和常见病害症状不同的新叶斑病。田间采集病样后,经病原菌分离、显微形态观察和分子生物学鉴定,证明该病由新月弯孢[(Curvularia lunata (Wakker) Boedijin]侵染引起,这是该种病原菌在中国危害辣椒的首次报道。生物学特性研究结果表明,玉米粉、30 ℃、pH 7.0、连续光照或光暗交替、麦芽糖和酵母提取物为病原菌最适培养条件,分生孢子最适萌发温度和致死温度分别为22~33 ℃和60 ℃（10 min）。12种杀菌剂的室内药剂筛选结果表明,45%咪鲜胺EW抑菌效果最好,浓度为1.0 mg/L时抑菌率达97.8%。16%乙霉威·10%嘧霉胺WP、25%三唑酮WP、65%代森锌WP和80%代森锰锌WP也有较好的抑菌效果,而70%甲基硫菌灵WP、80%多菌灵WP几乎无抑菌作用。     

木薯褐斑病菌的室内药剂筛选

采用孢子萌发法对分离自海南的木薯褐斑病菌进行了10种杀菌剂的室内筛选。结果表明,国光多菌灵(50%多菌灵WP)和咪鲜胺(25%咪鲜胺EC)的EC50值最小,抑菌效果最好;腐霉利(50%WP)的EC50值最大,抑菌效果最差。建议生产上使用多菌灵和咪鲜胺等来防治木薯褐斑病。     

温度调控对玉米弯孢叶斑病菌侵染的影响

玉米弯孢叶斑病菌菌丝生长的温度范围为6～40℃,最适为28～32℃;分生孢子萌发的温度范围为8～40℃,最适为25～35℃;病残体产孢的温度范围为8～38℃,且随着温度的升高,病残体产孢时间缩短,当温度为20～35℃时,保湿24h即可产生大量的分生孢子。弯孢菌在10～38℃都可以侵染玉米植株,使其发病;但在30℃时,病害的潜育期最短,病情发展最快。     

甜瓜棒孢叶斑病病原菌鉴定及其生物学特性研究

对海南三亚发生的甜瓜棒孢叶斑病的危害症状进行了系统的描述,采用致病性试验、形态学观察及分子生物学的方法对引起该病的病原菌进行了鉴定,同时采用菌落生长法和玻片法测定了病原菌的生物学特性。结果表明：甜瓜棒孢叶斑病的病原菌为多主棒孢霉[Corynespora cassiicola（Berk. & Curst.）Wei];病原菌菌丝生长的最适宜培养基为大豆培养基,最适温度为 24~28 ℃,致死温度和时间为55 ℃、15 min,最适pH为 8~10,光照有利于菌丝生长,最适碳源为乳糖,最适氮源为NaNO3;分生孢子萌发的最适温度为 24 ℃,致死温度和时间为50 ℃、20 min。     

海南大棚西瓜枯萎病病原菌生物学特性及室内毒力测定

对供试菌株海南大棚西瓜枯萎病病原菌尖孢镰刀菌西瓜专化型进行了生物学特性的研究及杀菌剂室内毒力测定。生物学测定结果表明：菌丝在西瓜汁培养基上生长最好;菌丝生长和孢子萌发的最适温度分别为28和30℃;菌丝生长和孢子萌发最适pH值分别为7～8和7～9;光暗交替有利于菌丝生长;孢子致死温度为60℃、5 min;果糖和葡萄糖作为碳源利于菌丝生长;酵母浸粉和蛋白胨作为氮源利于菌丝生长。室内毒力测定结果表明：50%咪鲜胺锰盐WP对西瓜枯萎病菌的抑菌效果最好,其EC50为0.730 9 μg/mL;32.5%苯甲嘧菌酯SC、30%苯甲·丙环唑EC、10%苯醚甲环唑WG、25%溴菌·多菌灵WP和25%溴菌腈WP对海南大棚西瓜枯萎病菌也有较好的抑制效果,其EC50为1.884 7～8.161 0 μg/mL,该研究为田间防治海南大棚西瓜枯萎病提供了基础数据。     

巴西橡胶树棒孢霉落叶病病原菌的生物学特性

研究多主棒孢菌(Corynespora cassiicola)的生物学特性,结果表明,菌丝生长的最适温度为28℃,最适pH为6～9,孢子萌发的最适温度为28～30℃。该菌能有效利用各种碳源和氮源,碳源以麦芽糖最好,氮源以蛋白胨最好。光照处理对菌丝生长速度影响不显著,交替光照有利于产孢。菌丝致死温度是60℃,15min;分生孢子的致死温度是55℃,5min。在PDA,PSA,Czapek等培养基上生长良好,但不能大量产孢,在保湿的卫生纸、玻璃片和橡胶离体叶片上,能大量产孢。     

中国木薯白点病发生调查及病原生物学特性研究

2007—2018年,本课题组在对中国木薯主栽区的病害调查中发现了一种国内尚未记载的叶斑病。病害主要危害叶片,形成圆形或不规则形、常密集分布的白色至黄褐色的病斑,故命名为白点病。该病在云南、海南、广西等地区均有发生,绝大多数主栽品种和部分新育成种质均受害。经病菌分离和回接实验以及病菌形态观察、核糖体基因间隔区和β-微管蛋白基因序列分析,将该病病原鉴定为链格孢(Alternaria alternata)。病菌离体培养实验表明,菌丝生长最适条件为V9、OA、CA或CMA培养基,28℃,D-麦芽糖、D-山梨醇或D-乳糖,硝酸钠,光暗交替,pH8。分生孢子萌发最适温度为28℃,而致死温度为60℃处理5min。杀菌剂敏感性测定结果表明,在所测试的10种药剂中,10%苯醚甲环唑WG和25%吡唑醚菌酯WG的EC50值分别为0.12、0.47 mg/L,对菌丝生长抑制率最高。     

中国2种橡胶树炭疽病菌对咪鲜胺敏感性比较

炭疽病是橡胶树上一种重要的叶部病害,主要病原有胶孢炭疽菌和尖孢炭疽菌。为了解中国各植胶区炭疽菌对咪鲜胺的敏感性,采用生长速率法室内测定来自海南、云南、广东和广西4省(区)22株橡胶树胶孢炭疽病菌和15株尖孢炭疽菌对咪鲜胺的敏感性。结果表明:供试的37株橡胶炭疽病菌菌株对咪鲜胺的EC_(50)值为0.022 0~0.272 1 mg/L,平均为(0.061 7±0.055 4)mg/L,EC_(50)最大值是最小值的12.5倍。其中89.2%参试菌株的EC_(50)值介于0~0.100 0 mg/L。根据成组t检验分析结果表明,目前中国4个植胶区的2种橡胶炭疽病菌对咪鲜胺敏感性无明显差异。除了来自海南和云南地区的尖孢炭疽菌有显著性差异外,其他来自不同省份的胶孢炭疽菌和尖孢炭疽菌对咪鲜胺敏感性均无明显差异。研究显示中国橡胶炭疽菌对咪鲜胺仍具有较高的敏感性,但菌株间敏感性有一定的差异,存在一定的潜在抗性风险。     

Effect of a continuous hot water treatment of potato tubers on seed-borne fungal pathogens

Summary The viability of five pathogens was decreased by treatment with hot water when tested in vitro.Polyscytalum pustulans was most sensitive andRhizoctonia solani least sensitive. Potato tubers were exposed to 55°C for 5 min in a commercial continuous hot water treatment plant using naturally contaminated seed tubers and tubers which had been inoculated by dipping in comminuted cultures. The frequency of eyes colonised byP. pustulans, Helminthosporium solani, andR. solani was reduced to virtually zero and the effect persisted on tubers subsequently stored at 4°C and at 15°C for up to 16 wk. Results withColletotrichum coccodes were inconclusive. Treatment suppressedPenicillium spp. which, however, rapidly recolonised the eyes during storage, leading to higher contamination levels in the treated than in the untreated tubers. With tubers inoculated withPhoma foveata, good control was achieved when the incubation period before treatment was 10 d but not when the period was 42 d.     

Assessing general combining ability for gangrene resistance by means of a glasshouse seedling test

Summary A seedling progeny test for resistance to gangrene (Phoma foveata) was used to evaluate progenies from a 15×15 half diallel set of crosses, including 14 selfs and 25 reciprocal crosses, which was originally made to investigate the inheritance of resistance to late blight and cyst nematodes. Nine out of the 14 selfs were more susceptible than the crosses involving their parents, so that overall the selfs were slightly more susceptible than the crosses, thus providing evidence of non-additive gene action in favour of resistance. However, when the selfs were omitted from the analysis, all of the variation between progenies could be attributed to differences in the General Combining Abilities (GCAs) of their parents. The four parents with the best GCAs for gangrene resistance all had sizeable contributions fromSolanum tuberosum subsp.andigena in their pedigrees.     

玉米圆斑病拮抗菌芽孢杆菌21的鉴定及抑菌研究

利用形态特征、培养性状、生理生化特征及16Sr DNA序列分析,对获得的具有生防潜力的芽孢杆菌21进行鉴定,确定该菌株为枯草芽孢杆菌(Bacillus subtilis spp.)。利用显微观察法,研究枯草芽孢杆菌21对玉米圆斑病菌的抑制作用,结果显示,该菌株不同浓度发酵液处理后玉米圆斑病菌孢子萌发率出现下降趋势,萌发率最低为0;经发酵液处理后的玉米圆斑病菌芽管产生畸形,在发酵液浓度为90%时,芽管畸形最严重;处理后的玉米圆斑病菌菌丝出现畸形,菌丝中的内容物有外渗趋势。     

The fermentation of trahanas: a milk-wheat flour combination

The fermented food, trahanas (a milk-wheat flour combination prepared in Greece), was studied to determine the microbiological and chemical changes that occur during fermentation. It is a lactic acid bacterial fermentation in whichStreptococcus lactis, Streptococcus diacetylactis, Leuconostoc cremoris, Lactobacillus lactis, Lactobacillus casei, Lactobacillus bulgaricus andLactobacillus acidophilus play the major acid- and aroma-producing role. The whole fermentation lasts about 50 hours. The pH of the final dried trahanas was 4.07–4.75, the acidity 0.60–1.00%, the moisture content 8.6–11.5% and the protein content 10.4–13.6%. The product offers possibilities as an increased nutritive value or high-protein food.     

Screening potato cultivars for common scab of potato in a naturally infested field

Summary Twenty seven cultivars of potato were screened for common scab grown in a commercial field in two successive years (1996–97 and 1997–98). Eight cultivars were least susceptible and the others ranged from medium susceptible to very highly susceptible. None of the cultivars was resistant. Most showed a stable resistance reaction in both years.     

Contamination of pathogen-free seed potato stocks byErwinia carotovora during multiplication: Results of a six-year monitoring study

Summary Recontamination byErwinia carotovora of seed potato stocks (VT) derived from stem cuttings in the process of multiplication was monitored on four farms in the east of Scotland from 1973 to 1978. Randomly selected VT stocks of different ages from a wider range of farms were also examined. The results showed that although contamination can occur early during stock multiplication there was, in general, no stepwise increase in contamination level from one generation to the next. However, contamination tended to be greater after the third multiplication year when stocks are grown by conventional methods used for lower-grade seed stocks. It is notable that contamination was consistently high on some farms and low on others. Contamination byE. carotovora var.carotovora tended to be greater than byE. carotovora var.atroseptica. These results may be explained by the farm practices of individual growers, soil moisture status and aerial transmission of the bacteria. The results also indicate that contamination of some potato stocks derived from stem cutting could be maintained at a low level over several generations more readily on some farms than on others.

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Zusammenfassung Von 1977 bis 1978 wurde auf vier Betrieben im Osten Schottlands im Laufe der Vermehrung von Pflanzkartoffelposten (SC), die von Stengelschnitten stammten, eine erneute Verseuchung durchErwinia carotovora beobachtet. Zudem wurden Stichproben von SC-Posten unterschiedlichen Alters aus einer gr?sseren Zahl von Betrieben untersucht. Die Zusammenfassung aller Ergebnisse der vier Betriebe zeigte, dass die ersten drie Generationen der Best?nde (Vermehrungsjahre 1 bis 3) zu weniger Ansteckung neigten als jene in den Jahren 4 und 5, wenn die Posten zur Erzielung von Saatgut tieferer Anbaustufen (Tabelle 1) mit konventionellen Handelsmethoden behandelt wurden. H?here Verseuchungsgrade wurden auch in den Jahren 4 und 5 in den Stichprobenposten erreicht (Tabelle 5). Wenn die Daten Betrieb für Betrieb analysiert wurden, fand man auf einigen Betrieben durchwegs hohe und auf anderen niedrige Verseuchungsgrade (Tabelle 2). Obwohl die Gesamtzusammenfassung der Daten (Tabelle 1) darauf hinwies, dass sowohlE. carotovora var.carotovora als auchE. carotovora var.atroseptica in ungef?hr gleichem Ausmass vorhanden waren, war der erste Organismus auf drei von vier Betrieben und der letztere auf dem vierten Betrieb vorherrschend (Tabelle 3). Obwohl die Ansteckung früh w?hrend der Bestandesvermehrung auftreten kann, gab es im allgemeinen keinen Entwicklung im Verseuchungsgrad. Statt dessen fiel der Verseuchungsgrad manchmal von einer Generation zur n?chsten (Tabelle 4). Diese Ergebnisse wurden versuchsweise mit dem Aufwand an Sorgfalt durch den einzelnen Pflanzen, durch den Zustand der Bodenfeuchtigkeit und durch den Lufttransport der Bakterien erkl?rt. Auf einigen Betrieben konnten die Kartoffelbest?nde nicht nur über einige Generationen relativ frei von Ansteckung durchE. carotovora erhalten werden, sondern weisen auch darauf hin, dass seit 1973 eine deutliche Verbesserung eintrat, selbst wenn einige Jahre n?sser und damit für die Bestandesverseuchung günstiger waren als andere (Tabelle 6). Parallel mit dieser Abnahme der Verseuchung verl?uft ein schw?cheres Auftreten der Schwarzbeinigkeit in Pflanzbest?nden, die seit 1973 zur Feldbesichtigung angemeldet wurden, als ein stets h?herer Anteil von Best?nden von Stengelschnitten stammte (Tabelle 7).

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Résumé La recontamination parErwinia carotovora de lignées de pommes de terre de semences (SC)_ provenant de bouturage dans le procédé de multiplication a été contr?lée dans quatre exploitations agricoles dans l'est de l'Ecosse de 1977 à 1978. Des lignées de bouture, sélectionnées au hasard, de différents ages, provenant d'une plus grande gamme d'exploitations, furent aussi examinées. Le résumé des résultats obtenus dans les quatre exploitations montraient que les trois premières générations de récolte (années de multiplication 1 à 3) avaient tendance à être moins contaminées que celles des années 4 et 5 quand les lignées avaient été traitées par des méthodes commerciales conventionnelles utilisées pour des clones de qualité inférieure (tableau 1). De hauts niveaux de contamination furent aussi obtenus dans les années 4 et 5 des lignées sélectionnées au hasard (tableau 5). Quand les données furent analysées ferme par ferme, les niveaux de contamination montrèrent qu'ils étaient significativement hauts dans certaines exploitations et bas dans d'autres (tableau 2). De la même manière, quoique le résumé des résultats (tableau 1) suggère queErwinia carotovora var.carotovora etErwinia carotovora var.atroseptica étaient présents en même quantité, le premier pathogène prédominait dans 3 exploitations sur quatre, et le dernier dans la quatrième exploitation (tableau 3). Bien que la contamination puisse avoir lieu au début de la multiplication de la lignée, il n'y a pas eu, en général, de niveau de contamination avancée. Le niveau de contamination tombait même quelquefois d'une génération à l'autre (tableau 4). Les résultats s'expliquaient par l'importance des précautions prises par les agriculteurs, le niveau d'humidité dans le sol et la transmission aérienne des bactéries. Non seulement on a pu maintenir dans quelques exploitations des lignées de pommes de terre relativement indemnes de contamination parErwinia carotovora pendant plusieurs générations, mais encore les résultats suggèrent qu'une amélioration notable a eu lieu depuis 1973 pendant certaines années plus humides, et par conséquent plus favorables à la contamination de la récolte que d'autres (tableau 6). Parallèlement à cette réduction de contamination, la jambe noire a eu moins d'importance dans les cultures de semence soumises au contr?le depuis 1973, tandis qu'une proportion de plus en plus élevée provenait de bouture (tableau 7).

     

Cisgenesis,a New Tool for Traditional Plant Breeding,Should be Exempted from the Regulation on Genetically Modified Organisms in a Step by Step Approach

Modern potato breeding requires over 100,000 seedlings per new variety. Main reasons are (1) the increasing number of traits that have to be combined in this tetraploid vegetatively propagated crop, and (2) an increasing number of traits (e.g., resistance to biotic stress) originates from wild species. Pre-breeding by introgression or induced translocation is an expensive way of transferring single traits (such as R-genes, coding for resistance to biotic stress) to the cultivated plant. The most important obstacle is simultaneous transfer of undesired neighbouring alien alleles as linkage drag. Stacking several genes from different wild sources is increasing this linkage drag problem tremendously. Biotechnology has enabled transformation of alien genes into the plant. Initially, transgenes were originating mainly from microorganisms, viruses or non-crossable plant species, or they were chimeric. Moreover, selection markers coding for antibiotic resistance or herbicide resistance were needed. Transgenes are a new gene source for plant breeding and, therefore, additional regulations like the EU Directive 2001/18/EC were developed. Because of a strong opposition against genetic modification of plants in Europe, the application of this Directive is strict, very expensive, hampering the introduction of genetically modified (GM) crops and the use of this technology by small and medium-sized enterprises (SMEs). Currently, GM crops are almost the exclusive domain of multinationals. Meanwhile, not only transgenes but also natural genes from the plant species itself or from crossable plant species, called cisgenes, are available and the alien selection genes can be avoided in the end product. This opens the way for cisgenic crops without alien genes. The existing EU directive for GM organisms is not designed for this new development. The cisgenes belong to the existing breeders’ gene pool. The use of this classical gene pool has been regulated already in agreements regarding breeders’ rights. We are proposing a step by step approach starting with a crop and gene specific derogation and monitoring towards a general exemption of cisgenic plants from the Directive. Two examples, i.e. development of cisgenic potato for resistance to Phytophthora infestans and cisgenic apple for resistance to Venturia inaequalis are discussed shortly for illustration of the importance of cisgenesis as a new tool for traditional plant breeding. Cisgenesis is simplifying introgression and induced translocation breeding tremendously and is highly recommended for SMEs and developing countries.     

白僵菌亲环素蛋白基因BbCPLA的克隆与分析

亲环素几乎存在于所有的生命体中,并存在于细胞液和各个细胞器中,具有分布广泛性及结构的高度保守性等特点,在细胞的生命活动中起着重要的作用。球孢白僵菌是最常见的昆虫病原真菌之一,已成功应用于玉米螟和松毛虫等害虫的生物防治。本研究首次从玉米螟虫生真菌球孢白僵菌中分离到一个亲环素蛋白基因BbCPLA,该基因片段长度为606 bp,基因序列与来源于小菜蛾虫生真菌白僵菌的亲环素白蛋白基因A对应编码序列(AF542516)同源性为99.8%;该基因的编码区为495 bp,编码了一个由164个氨基酸组成的蛋白,与蛋白数据库中同源蛋白(AAN39296)的最高同源性为99.4%。     

Production of min-seed tubers using a modular system of plant micropropagation

Summary An efficient and low cost modular system for the production of mini-tubers as a source for conventional seed tubers is reported. In this system, microplants are soil grown and produce minitubers of 5 to 25 mm diameter. The system is based on the use of pre-sterilized disposable plastic containers which allow micropropagation, weaning, hardening, and soil growing of micropropagated plants in the same container. Depending upon the cultivar, the modular system allows production of 2900 to 6600 mini-tubers/m² in a glasshouse.     

Non-destructive estimation of potato leaf area index using a fish-eye radiometer

Summary Leaf area index (LAI) is widely used in many facets of potato (Solanum tuberosum L.) modelling but direct measurements have historically been difficult. This investigation tested the accuracy of a commercially available instrument (LI-COR LAI-2000) for measuring LAI non-destructively on a potato crop. Accurate estimates of LAI were difficult to obtain with small plots of≈1 m². Results from larger field plots were extremely favourable and indicate that non-destructive measurements of LAI in situ can routinely be estimated within 5 to 10% of the destructively measured LAI. Six thinning tests performed on four potato cultivars produced average root mean square error measurements of LAI that ranged from 0.09 to 0.27.