病原菌与自然植物种群

在自然植物种群中,病原菌与寄主植物不仅在个体发育的水平上相互作用,而且在系统发育的水平上相互作用。这后一种相互作用的不是病原菌与寄主植物的共进化。本文论述了病原菌与寄主植物共进化的主要方面原菌的致病力和寄主植物种群的遗传结构。鉴于传媒方式在进化上具有重要意义,本文还简单介绍了媒体传布的菌病的种群模型。     

病原菌与自然植物种群Ⅱ病原菌与植物种群生物学

病原菌在自然植物种群中普遍存在,其对寄主植物的生长发育,对寄主植物种群的大小、结构、动态、遗传和进化等都有重要影响。本文着重论述：１）病原菌对寄主植物个体的影响;２）病原菌对寄主植物种群生物学的影响;３）菌病发生的空间格局;４）病原菌感染的种群模型。     

自然植物种群中病原菌与寄主植物相互作用的遗传学

在农业种群中,作物和菌病相互作用的遗传学已为人们所广泛研究,但对自然植物种群中病原菌与其寄主相互作用体系的某些重要现象却缺乏足够的重视。本文主要论述寄主与病原菌相互作用的遗传学本质;寄主抗性基因和病原菌毒性基因的获得代价及对各自适应力的影响;简单介绍了寄主-病原菌作用体系在种群水平上的遗传学内容及共进化的意义。     

银叶老鹳草(Geranium sylvaticum)种群中诱导保护抗性和病原菌相互作用的研究（英）

本文通过自然植物种群接种实验,人工接种实验和野外调查研究了（Geranium sylvaticum)对老鹳草单孢锈菌（Uromyces geranii)（长生活史）的抗病性在受柄锈菌（Puccinia)（短生活史）感病前后和受2种柄锈菌（P.leveillei或P.morthieri)感病后有无区别,以及在同一季节里感染同一寄主植物的长生活史单孢锈菌和短生活史柄锈菌间的相互作用,病原菌间的相互作用使寄主植物产生诱导保护抗性。结果表明,P.leveillei可诱导寄主植物产生短时间的保护抗性,而P.morthieri可能诱导寄主植物产生长时期的保护抗性,诱导保护抗性可能是影响自然植物种群中植病式样的重要因素之一。     

病原菌逃避宿主细胞防御的策略

病原菌对宿主致病是病原菌与宿主复杂相互作用的结果。病原菌与宿主相互作用可造成宿主在细胞、组织及器官不同水平的损伤。病原菌对宿主的致病性及毒力,一方面在于病原菌,另一方面在于宿主因素以及宿主与病原菌的相互作用。病原菌-宿主在细胞水平的相互作用是病原菌感染致病的重要环节。结合本课题组对猪链球菌的研究,从黏附与定殖、侵袭、逃避与扩散等方面概述病原菌逃避宿主细胞防御的机制。     

竹类植物种群生态学研究进展与展望

综述了竹类种群生理生态学、种群动态、繁殖特性、无性系种群特征等几个方面的研究进展,概括了群落水平上竹类种群对森林更新的影响。并从竹类种群克隆多样性与微进化、生长适应机理、开花机制,以及竹类种群与林窗更新等四个方面展望未来竹类种群生态学研究的重点和主要趋势。     

植物与病原菌互作的蛋白质组学研究进展

深入认识植物与病原菌的识别方式、亲和性或非亲和性的互作模式,对于揭示植物-病原菌互作机制研究具有重要意义.利用蛋白质组学方法研究病原菌侵染植物过程,分析相关的基因和蛋白,有助于从分子水平上探究植物-病原菌相互作用机制.本文概述了植物-病原菌的互作机制,系统介绍了差异蛋白质组学分析方法在植物-病原真菌、植物-病原细菌两类互作系统中的应用,分析了植物与病原菌互作过程中可能涉及的差异表达功能蛋白,并对当前蛋白质组学技术在植物与病原菌互作研究中存在的诸多问题进行了探讨.     

病原菌毒力岛研究进展

毒力岛作为基因组岛的一种亚类，是细菌染色体上具有特定结构和功能特征的可移动基因大片段，经基因水平转移（转导、接合或转化）获得，可使细菌基因组进化在短期内发生“量的飞跃”，直接或间接增强细菌的生态适应性，与病原菌的致病性密切相关。毒力岛存在于多种动植物病原细菌中，对于细菌的毒力变异、遗传进化甚至新病原亚种形成有重要意义。简要综述了病原菌毒力岛的研究进展，介绍了毒力岛的结构、功能特征及其在病原菌进化中作用。     

相互作用的集合种群研究动态

在集合种群水平上,两个或更多物种可以生活在同一个斑块网络中而没有相互作用。但在很多情况下,种间的相瓦作用会影响种群的迁移率、灭绝率和侵占率,从而调节相应物种的集合种群动态。这方面的研究主要有集合种群水平上物种之问的竞争、捕食以及在没有任何环境异质性的条件下物种在空间上聚集分布的产生和维持等。综述了近年来关于集合种群水平上的竞争,捕食者和猎物系统以及捕食与复杂空问动态的最新研究成果。     

植物边缘种群遗传多样性研究进展

边缘种群指地理分布边缘可检测到的一定数量的同种个体集合, 准确评价其遗传多样性对于理解第四纪冰期后气候变化对物种边缘扩展或收缩、遗传资源保护与利用以及物种形成等有重要意义。该文探讨了维持植物边缘种群遗传多样性的进化机制, 分析交配系统对物种边缘及其遗传多样性的影响, 比较了边缘与中心种群遗传多样性的差异及其形成的生态与进化过程, 并探讨了边缘种群遗传多样性与其所在的群落物种多样性的关系及理论基础。该文提出今后研究的重点是应用全基因组序列或转录组基因序列研究前缘-后缘种群之间或边缘-中心种群之间的适应性差异, 边缘种群与所在群落其他物种之间相互作用的分子机制, 深入解析边缘种群对环境的适应及边缘种群遗传多样性与群落物种多样性关系的生态与进化过程。     

AM真菌在草原生态系统中的功能

AM真菌是土壤生态系统中重要的微生物类群,能与陆地生态系统中80%以上的高等植物建立共生体系。目前,AM真菌在维持草原生态系统稳定性中的功能已经成为生态学研究的热点问题之一。基于此,从植物个体、种群、群落和生态系统等不同层次探究AM真菌在维持植物群落多样性和草原生态系统稳定性中的功能。分析发现在个体水平上,AM真菌对宿主植物具有促生效应、抑制效应或中性效应。在种群水平上,分析AM真菌对不同宿主植物吸收土壤矿质营养的分配和调控策略,围绕构成草原植被的两大组成成分:牧草和有毒植物,论述AM真菌对植物种群增长和衰败的调控机制,并从草原植物群落的物种多样性和稳定性角度,探讨AM真菌与植物群落之间的相关性。在生态系统水平上,围绕AM真菌对草原生态系统的演替和退化草原的修复等展开论述,以期为利用AM真菌开展草原生态系统保护和恢复治理提供理论依据,并对草原菌根生态学领域未来的研究进行展望。     

AM真菌在植物病虫害生物防治中的作用机制

丛枝菌根(Arbuscular Mycorrhizae,AM)真菌是一类广泛分布于土壤生态系统中的有益微生物,能与大约80%的陆生高等植物形成共生体。由土传病原物侵染引起的土传病害被植物病理学界认定为最难防治的病害之一。研究表明,AM真菌能够拮抗由真菌、线虫、细菌等病原体引起的土传性植物病害,诱导宿主植物增强对病虫害的耐/抗病性。当前,利用AM真菌开展病虫害的生物防治已经引起生态学家和植物病理学家的广泛关注。基于此,围绕AM真菌在植物病虫害生物防治中的最新研究进展,从AM真菌改变植物根系形态结构、调节次生代谢产物的合成、改善植物根际微环境、与病原微生物直接竞争入侵位点和营养分配、诱导植株体内抗病防御体系的形成等角度,探究AM真菌在植物病虫害防治中的作用机理,以期为利用AM真菌开展植物病虫害的生物防治提供理论依据,并对本领域未来的发展方向和应用前景进行展望。     

Sugar transporters in plants and in their interactions with fungi

Sucrose and monosaccharide transporters mediate long distance transport of sugar from source to sink organs and constitute key components for carbon partitioning at the whole plant level and in interactions with fungi. Even if numerous families of plant sugar transporters are defined; efflux capacities, subcellular localization and association to membrane rafts have only been recently reported. On the fungal side, the investigation of sugar transport mechanisms in mutualistic and pathogenic interactions is now emerging. Here, we review the essential role of sugar transporters for distribution of carbohydrates inside plant cells, as well as for plant-fungal interaction functioning. Altogether these data highlight the need for a better comprehension of the mechanisms underlying sugar exchanges between fungi and their host plants.     

Fungal Pls1 tetraspanins as key factors of penetration into host plants: a role in re-establishing polarized growth in the appressorium?

The ability of plant pathogenic fungi to infect their host depends on successful penetration into plant tissues. This process often involves the differentiation of a specialized cell, the appressorium. Signalling pathways required for appressorium formation are conserved among fungi. However, the functions involved in appressorium maturation and penetration peg formation are still poorly understood. Recent studies have shown that Pls1 tetraspanins control an appressorial function required for penetration into host plants and are likely conserved among plant pathogenic fungi. Tetraspanins are small membrane proteins widely distributed among ascomycetes and basidiomycetes defining two distinct families; Pls1 tetraspanins are found in both ascomycetes and basidiomycetes and Tsp2 tetraspanins are specific to basidiomycetes. Both fungal tetraspanins families have similar secondary structures shared with animal tetraspanins. Pls1 tetraspanins are present as single genes in genomes of ascomycetes, allowing a unique opportunity to study their function in appressorium mediated penetration. Experimental evidence suggests that Pls1 tetraspanins are required for the formation of the penetration peg at the base of the appressorium, probably through re-establishing cell polarity.     

Horizontal gene and chromosome transfer in plant pathogenic fungi affecting host range

Plant pathogenic fungi adapt quickly to changing environments including overcoming plant disease resistance genes. This is usually achieved by mutations in single effector genes of the pathogens, enabling them to avoid recognition by the host plant. In addition, horizontal gene transfer (HGT) and horizontal chromosome transfer (HCT) provide a means for pathogens to broaden their host range. Recently, several reports have appeared in the literature on HGT, HCT and hybridization between plant pathogenic fungi that affect their host range, including species of Stagonospora/Pyrenophora, Fusarium and Alternaria. Evidence is given that HGT of the ToxA gene from Stagonospora nodorum to Pyrenophora tritici-repentis enabled the latter fungus to cause a serious disease in wheat. A nonpathogenic Fusarium species can become pathogenic on tomato by HCT of a pathogenicity chromosome from Fusarium oxysporum f.sp lycopersici, a well-known pathogen of tomato. Similarly, Alternaria species can broaden their host range by HCT of a single chromosome carrying a cluster of genes encoding host-specific toxins that enabled them to become pathogenic on new hosts such as apple, Japanese pear, strawberry and tomato, respectively. The mechanisms HGT and HCT and their impact on potential emergence of fungal plant pathogens adapted to new host plants will be discussed.     

Powdery mildew susceptibility and biotrophic infection strategies

Plants are resistant to most potentially pathogenic microbes. This forces plant pathogens to develop sophisticated strategies to overcome basic plant resistance, either by masking intrusion or by suppression of host defences. This is particularly true for fungal pathogens, which establish long lasting interactions with living host tissue, without causing visible damage to invaded cells. The interactions of cereal crops and Arabidopsis with powdery mildew fungi are model systems for understanding host resistance. Currently, these systems are also promoting the understanding of fungal infection by identifying fungal pathogenicity and virulence factors and host target sites. This minireview focuses on recent findings about host susceptibility and the way powdery mildew fungi might induce it.     

Dimorphism in fungal plant pathogens

Fungi are mostly sessile organisms, and thus have evolved ways to cope with environmental changes. Many fungi produce 'dormant' structures, which allow them to survive periods of unfavorable conditions. Another ingenious active approach to a changing environment has been adopted by the 'dimorphic fungi', which simply shift their thallic organization as a way to adapt and thrive in the new conditions. Dimorphism is extensively exploited by both plant and animal pathogenic fungi, where the encounter with the host prompts a shift in the mode of growth. In this review, we focus on the phenomenon of dimorphism among plant pathogenic fungi through discussion of several relatively well-studied exemplar species.     

Exploring the potentialities of beneficial endophytes for improved plant growth

Pathogen affects plant growth, host health and productivity. Endophytes, presumed to live inside the plant tissues, might be helpful in sustaining the future of agriculture. Although recent studies have proven that endophytes can be pathogenic, commensal, non-pathogenic, and/or beneficial, this review will focus on the beneficial category only. Beneficial endophytes produce a number of compounds which are useful for protecting plants from environmental conditions, enhancing plant growth and sustainability, while living conveniently inside the hosts. The population of endophytes is majorly controlled by location, and climatic conditions where the host plant grows. Often the most frequently isolated endophytes from the tissues of the plant are fungi, but sometimes greater numbers of bacteria are isolated. Beneficial endophytes stand a chance to replace the synthetic chemicals currently being used for plant growth promotion if carefully explored by researchers and embraced by policymakers. However, the roles of endophytes in plant growth improvement and their behavior in the host plant have not been fully understood. This review presents the current development of research into beneficial endophytes and their effect in improving plant growth.     

1‐Phenyl‐3‐pentanone,a Volatile Compound from the Edible Mushroom Mycoleptodonoides aitchisonii Active Against Some Phytopathogenic Fungi

Volatiles produced by mycelia of mushrooms with aromatic odour were investigated for their antifungal activity against plant‐pathogenic fungi. The results of the screening of 23 species of basidiomycetes revealed that volatile substances from mycelia of Mycoleptodonoides aitchisonii (TUFC10099), an edible mushroom, strongly inhibited the mycelial growth, spore germination and lesion formation on host leaves of some plant‐pathogenic fungi including Alternaria alternata, A. brassicicola, A. brassicae, Colletotrichum orbiculare and Corynespora cassiicola. The volatile compounds were isolated from the culture filtrate of M. aitchisonii, and 1‐phenyl‐3‐pentanone was identified as a major antifungal volatile. The compound had significantly inhibitory activity against plant‐pathogenic fungi at 35 ppm. This is the first report that the volatile compound produced by mycelia of M. aitchisonii has antifungal activity against plant‐pathogenic fungi.