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1.
Rice blast fungus isolates were collected in Kyushu to investigate resistance to scytalone dehydratase inhibitors of melanin biosynthesis (MBI-D). In 2001, failure of control of rice blast was reported in the Saga prefecture, where MBI-Ds have been used since 1998. At that time, the distribution of resistant isolates was mainly limited to that area. However, in 2002, resistant isolates were detected in all prefectures of Kyushu. DNA fingerprinting analysis showed that the mutation causing resistance to MBI-Ds had arisen independently in each area. These data suggest that resistant isolates may occur in any area and become dominant under continuous selection pressure for MBI-Ds. Nevertheless, resistant strains can be controlled by reductase inhibitors of melanin biosynthesis (MBI-R) or commercial rice seed disinfectants. 相似文献
2.
We have established a simple diagnosis method for rice blast fungus resistant to MBI-D. This involves the preparation of PCR templates directly from the lesions in combination with primer-introduced restriction enzyme analysis PCR (PIRA-PCR). 相似文献
3.
Hirofumi Suzuki Fumihiko Suzuki Motoaki Kusaba Yukio Tosa 《Journal of General Plant Pathology》2012,78(2):106-114
In Mie Prefecture in Japan, rice blast isolates resistant to melanin biosynthesis inhibitors targeting scytalone dehydratase
(SDH) were first observed in 2005. To analyze the distribution of the resistant isolates, 527 isolates were collected from
wide areas in this prefecture during 2006 and 2007. Almost half of the isolates collected (233 of 527 isolates) carried a
point mutation in the SDH gene conferring the resistant phenotype. To compare population structures of resistant and sensitive
isolates, we analyzed the isolates with repetitive-element-based PCR DNA fingerprinting using a single primer complementary
to a sequence in the terminal inverted repeat of transposable element Pot2. A majority of the resistant isolates were classified into a single DNA fingerprint haplotype, Mie1. Despite its prevalence
in the resistant isolates, Mie1 was not found in the sensitive isolates. Furthermore, in a dendrogram constructed from the
DNA fingerprint data, Mie1 and six other haplotypes formed a cluster composed of resistant isolates alone. These results suggest
that the resistant isolates that belonged to the Mie1 haplotype had migrated from regions outside Mie Prefecture and selectively
propagated in a short period in this prefecture. 相似文献
4.
多主棒孢霉(Corynespora cassiicola)是世界范围内重要的植物病原真菌,其引起的草莓棒孢霉叶斑病对草莓产业的健康发展具有潜在威胁。小柱孢酮脱水酶(scytalone dehydratase,SCD)是真菌多聚二羟萘类(DHN)黑色素生物合成途径中的关键酶,在植物病原菌致病过程中发挥重要作用。本研究通过同源重组的方法获得了草莓多主棒孢霉小柱孢酮脱水酶基因(CcSCD1)的敲除突变体,并进行了回补和RT-PCR验证。与野生型相比,敲除突变体△CcSCD1-2表现为菌落无色素沉积、菌丝稀疏、产孢量显著下降、分生孢子无色较小以及致病力明显减弱。结果表明,CcSCD1参与调控多主棒孢霉的黑色素生物合成、营养生长、分生孢子产量及致病力。 相似文献
5.
干旱区生态环境制图的理论与方法 --以土地荒漠化图为例 总被引：2，自引：1，他引：2
土地荒漠化制图是生态环境专题制图的前沿领域，按照现代制图学的原理和土地荒漠化的分类体系，综合制图区域自然及人文要素的时空特征，应用遥感与GIS相结合的方法，编制了不同时期的专题类型图。新技术的应用，反映了信息化时代数字制图技术在土地荒漠化专题制图中的应用潜力，极大地丰富了专题制图学的内涵。同时，体现了专题地图高度的灵活性和强大的选择性，良好的现势性及动态性，制图过程的智能化及制图载体的多样化。本研究重点讨论了荒漠化类型的制图综合，专题要素的表现手法以及制图过程的数据挖掘等关键问题。 相似文献
6.
In this study,we provide the first evidence of two pairs of petals of the rapidly expanded and short-lived nocturnal flowers of Capparis spinosa L.(caper)during the prolonged drought period in Eastern Mediterranean region.The corolla of the winter-deciduous,perennial C.spinosa consists of two pairs of petals:a pair of white distinct petals and a pair of connate variegated petals with green basal parts.The results indicated the presence of substantially different amounts of chlorophyll in the two pairs of petals,while their carbohydrates’content is comparable with that of the green sepals.High resolution imaging of petal surfaces of short-lived flowers of C.spinosa, obtained by using scanning electron microscopy,revealed stomata on the adaxial epidermis on both the white and the green parts of the variegated petals;while dense hairs were found on the surface of the abaxial green parts of the variegated petals.Adaxial,epidermal cells of the variegated petals,viewed using atomic force microscopy,possess a submicron,cuticular microfolding that differs between the white and the green parts of the petals.It appears that microridges on the adaxial,white parts of petals of C.spinosa compensate for an increase in cell surface area of the short lived petals,while the roughness of the green parts of petals was found to be higher than that of the white parts.Thus,the micromorphology of surfaces of epidermal cells is expected to affect optical properties and wettability of the floral tissues.These findings may be particularly important for understanding the performance of the short-lived petals of C.spinosa,which are exposed to dryland environments. 相似文献
7.
5406细胞分裂素混合剂对杨树溃疡病抑制作用的研究 总被引：2，自引：0，他引：2
Streptomyces jingyanesis 5406细胞分裂素混合剂能明显地降低小美旱杨树溃疡病(Dothiorella gregariaSacc)的发病率.用100倍稀释液浸泡24小时处理,发病率为未处理的对照组的12.5%.用不同浓度的混合剂分别处理杨树溃疡病原菌和杨树枝条表明,这种混合剂能对杨树溃疡病菌有一定的抑制生长的作用:而且能明显地促进杨树干部愈杀组织形成的作用。试验还证明,在愈伤组织形成和发展过程中,过氧化物酶(PRO)活性始终处于较低水平. 相似文献
8.
Results are presented on the effect of immunosuppressive substances such as chlorambucil, cyclophosphamide, azathioprine, amethopterine and a cortizone derivate of betamethasone, on the development of Fasciola hepatica in the rat. The suppression of the immune response of the host to immunosuppressants was reflected in an earlier start of migration of the flukes to the common bile duct, and in an earlier onset of egg production as compared with that in the controls. Of the substances employed, cyclophosphamide and betamethasone were the most effective ones within the period from week 2--6 p.i., which is the time during which the migration of the flukes in the liver parenchyma is highest. Pathological changes in the liver of the animals were less marked than those of the infected controls. Evidence was obtained on an increased pathogenicity of infective larval flukes causing a higher mortality of the hosts in comparison with that of the control animals. On the other hand, the administration of immunosuppressants did neither influence the total number of developed flukes nor the appearance of eosinophilia in the peripheral blood of the treated animals. 相似文献
9.
浑善达克沙地榆树根系分布特征及生物量研究 总被引：20，自引：5，他引：20
本文采用挖掘法对浑善达克沙地榆树的根系进行了研究。研究表明 ,草被层的根系主要分布在土壤表层 ,榆树根系则占据了 2 0 cm以下的土层空间。根系的垂直分布在冠缘内主要集中在 2 m深范围内 ,冠缘外则集中分布在 1 m深的土层中 ,不同的根系剖面形成不同的根栖层 ;根系的水平分布呈近密远疏的趋势 ,其半径为 1 1 m左右。根量的垂直分布随土层深度增加呈先增加后降低的趋势 ;其水平分布随着距根基距离的增大而减少 ,以 3m内最为密集 ,冠缘内根量为冠缘外根量的 1 2倍。 相似文献
10.
M L Sanmartín F Alvarez H Gijón Botella R Iglesias J Estévez R López-Román 《Folia parasitologica》1992,39(4):355-367
We have carried out a morphometric study of the ascaridoid nematode Toxocara genettae, parasite of the small intestine of the genet Genetta genetta, with the aid of scanning electron microscopy (SEM). Host specimens were trapped in Galicia, NW Spain. The most characteristic features of this nematode are the absence of cervical alae, replaced by narrow lateral crests running along the length of the body and the presence of a mucron at the end of the male tail. Other features of interest include the number of labial denticles (90-98 and 96-102 on the dorsal lip, 82-96 and 90-96 on the subventral lip of male and female, respectively), the width of the transverse striations (25-28 microns) and, in many of the specimens examined, the position of the precloacal median papilla at the base of a well-defined cuticular pit. 相似文献
11.
塔里木河干流河道演变对两岸生态环境的影响研究 总被引：1，自引：0，他引：1
塔里木河干流位于塔里木盆地的腹地,文中在分析塔里木河干流河道演变规律的基础上,通过对塔里木河干流河道演变对两岸生态环境影响的分析,得出塔里木河干流河道演变中的洪水漫溢、河岸崩塌侵蚀与洲滩淤长、河势变化与改道、河势游荡与分汉等变化对两岸生态环境都有重要的影响. 相似文献
12.
林业碳汇核证减排量所有权归属的实践样态与应然思路 总被引：1，自引：0，他引：1
陈娟丽 《干旱区资源与环境》2021,35(4):1-9
林业碳汇核证减排量是应对气候变化领域的新生事物,其所有权归属是确保林业碳汇交易稳定的首要问题,但我国《民法典》物权编、自然资源法和碳排交易规范中均无明确规定,个别部门规章对其收益分配的规定有违上位法。实践中各类林业碳汇项目核证减排量所有权归属情形不尽一致的原因是多方面的:林业碳汇权利与采矿权、渔业权产生机理一致,依据土地和森林资源所有权这些"母权",核证减排量可归属的主体众多;我国森林资源用益物权体系结构复杂,搭建了多种归属路径;国际规则下林业碳汇项目参与主体多数涉外,加剧了归属随意化的趋势。在我国鼓励积极开展碳汇交易和推进法规制度建设的背景下,应尽快完善相关法律规范,将核证减排量"类型化"为自然资源性权利客体,圈定所有权归属主体范围,确定国家对核证减排量的管理者角色,确立同一项目核证减排量由多个参与主体共有的制度,遵循自愿公平原则合理分配转让收益,以及做好相关权属争议解决的法律准备。最终为拓宽放活经营权渠道,保障各方利益,乃至我国资源安全和气候安全提供法律支撑。 相似文献
13.
14.
不同灌溉量下春小麦土壤水分变化规律 总被引：1，自引：1，他引：0
研究了不同灌水量处理条件下春小麦土壤水分变化规律。结果表明:不同灌水量处理下土壤含水率在垂直方向上的变化规律一致,随着深度的增加,土壤含水率变异系数逐渐变小;在春小麦整个发育期,不同灌水量处理在拔节期耗水强度均达最大值,为其需水高峰期;从节水效益看,全生育期灌水量为428.6 mm的处理水分利用效率和灌溉水利用效率较好,灌溉效果最佳,达到节水灌溉效果。 相似文献
15.
首先,从水资源自然再生能力的基本概念探讨入手,提出了一种网格水文单元水资源自然更新率概念,用以表证该网格水文单元的水资源自然再生能力;在此基础上,建立了一种全新的水资源自然再生能力评价方法。其次,在基于GRID的泾河流域水量动态平衡模拟基础上,通过逐网格计算泾河流域1996年各月水资源自然更新率,来对泾河流域1996年水资源自然再生能力进行评价。评价结果表明:泾河流域水资源自然再生能力在年内时间尺度上存在明显的准周期运动规律。泾河流域水资源自然更新率在-1.5到1.5之间,4月为最低值,6月为最高值,整个趋势受降水量的影响较大,丰水期与枯水期差别明显。与此同时,泾河流域水资源自然再生能力也存在明显的空间分布规律,具体表现为泾河流域中部的水资源自然再生能力最高,流域南部地区中等,流域北部水资源自然再生能力较弱。水资源的这种空间分布规律主要取决于该流域降水、蒸发,以及植被与土壤等下垫面空间分布规律。 相似文献
16.
在回顾总结西北山川秀美建设区的生态环境的现状与面临的主要问题的基础上,提出了"山川秀美"工程可持续发展运行机制的涵义和应坚持的基本原则,指出"山川秀美"工程建设可持续发展运行机制的建设和健全,有利于维护、改革和完善现存的山川秀美体制,并确保山川秀美工程的健康运行.在这一过程中,引入绿色GDP核算指标不仅能为山川秀美建设区自身的可持续发展、避免重走过去资源为代价的老路超到指导作用,而且对于新形势下国家建立绿色GDP核算指标的工作很有裨益和借鉴,值得我们进行深入地研究和探索. 相似文献
17.
西辽河断流问题及解决对策 总被引：5，自引：0，他引：5
西辽河断流的发生具有周期规律性,90年代后期进入新的断流高峰,断流发生的频率和持续的时间较之前周期有所增加,而且有继续断流的趋势,形势严峻。断流不仅引起一系列生态和环境问题,还严重制约流域经济社会发展。通过分析发现,西辽河断流与支流断流有密切联系,流域降水减少、水利工程拦截和社会经济用水增加都是断流的重要原因。并提出从四个方面缓解断流的对策:加强水源地保护,减少支流断流;合理调度水库,强化流域管理;调整产业结构,提高用水效率;开辟新水源,提高水资源的再生能力。 相似文献
18.
北京地区小麦白粉病初侵染源的研究 总被引：2，自引：0，他引：2
各种自然条件下闭囊壳越夏试验结果表明:土壤中,地面和麦茬上,麦垛顶层和底层,室外自然条件下的闭囊壳在秋苗出土前相继变成空壳;室内自然条件下,种子中以及麦垛中层的闭囊壳在越夏季节期间,子囊原生质体结构发生畸变,失去形成子囊孢子的能力。上述各种环境中的闭囊壳先后于7月中旬至9月上旬失去生活力和传病能力,均不能越夏后成为小麦白粉病的初侵染源。在小麦播种时用做过上述各种处理的闭囊壳进行隔离接种试验,试验结果进一步证实了越夏试验结论的正确性。在房山区白粉病发生严重的张坊及十渡一带山区,通过对自生麦苗和小麦秋苗感染白粉病情况的野外调查发现:海拔140m以上山区自生麦苗上的分生孢子是北京地区小麦白粉病在秋苗上的主要侵染源之一。 相似文献
19.
Stéphane Pietravalle Stéphane Lemarié Frank van den Bosch 《European journal of plant pathology / European Foundation for Plant Pathology》2006,114(1):107-116
A seasonal model, where a growing season is defined as the time between sowing and harvest and alternates with an inter-crop
period, was derived to study the effects of the ‘cost of virulence’ and cropping ratio on durability of resistance. We assumed
a single strain of virulent pathogen, a single strain of avirulent pathogen and two cultivars (one resistant and one susceptible)
and studied two measures of durability of resistance (‘take-over time’ and ‘usefulness time’). Take-over time is defined as
the time needed for the virulent strain of the pathogen to reach a preset threshold and predominate over the previous pathogen
population. Usefulness time is the time needed before the estimated gain in green canopy area duration per plant through the
use of the resistant cultivar becomes negligible. The model suggested that, although it could take several seasons before
the virulent strain of the pathogen predominated over the previous pathogen population, the usefulness time of the resistant
cultivar was always much shorter. Furthermore, increasing selection for the virulent strain of the pathogen (through increasing
the cropping ratio of the resistant cultivar) caused the virulent strain of the pathogen to invade the system more rapidly.
Cost of virulence, reflecting differences in pathogen infection rates between the four possible combinations of cultivar/pathogen
strain, significantly affected durability of resistance, with the dynamics of the virulent and avirulent strains ranging from
a case where the virulent strain of the pathogen died out to a case where the virulent strain of the pathogen invaded the
resident pathogen population. An intermediate state, where the system reached equilibrium and the virulent strain of the pathogen
neither became predominant nor died out, was defined as ‘coexistence’ of both strains of the pathogen. Occurrence of coexistence
was directly related to the cost of virulence since it did not occur when virulence of the pathogen did not have a fitness
cost. Two methods to include cost of virulence in the model gave similar results in relation to the two measures of durability
of resistance studied. 相似文献
20.
塔里木河下游应急输水植被响应效果调查与初步分析 总被引：15，自引：4，他引：15
本文根据塔里木河下游四次应急输水后不同断面、离河岸不同距离植被恢复的现地调查数据 ,结合输水河道两侧相应地下水位空间变化规律 ,分析塔河下游输水河道两侧不同地下水埋深梯度地表相应植物的生态恢复指征 ,以此为输水的生态有效范围和输水周期提供科学依据 ,为科学的指导和调度塔河下游生态输水提供依据。 相似文献