环境因子对蕨类植物孢子萌发的影响

蕨类植物通过孢子萌发形成独立生活的配子体,配子体能够形成精子器和颈卵器,进而通过受精作用形成新的孢子体。孢子萌发是蕨类植物生活史过程中配子体世代向孢子体世代转变的关键步骤。同时,此过程不仅受到多种环境因子的影响,也是研究细胞核极性移动、细胞不对称分裂、假根极性生长等独特的细胞学事件的良好模型。迄今为止,人们已经研究发现多种环境因子对约200余种蕨类植物孢子萌发有影响。总结了环境因子对蕨类植物孢子萌发影响的规律如下:(1)孢子萌发除了受到光照强度影响外,主要受光质的影响,光质的影响主要表现为4种方式:①孢子萌发受红光刺激与远红光抑制像开关一样调控;②孢子萌发不受远红光抑制;③孢子萌发受蓝光抑制;④孢子只能在黑暗条件下萌发。(2)重力作用会影响孢子细胞核移动,进而影响孢子细胞发育的极性。(3)赤霉素(GA)能增加孢子萌发率或帮助孢子打破休眠。成精子囊素与GA作用相似,启动或促进孢子萌发。而脱落酸(ABA)、茉莉酸(JA)和乙烯等其它激素对孢子萌发的影响相对较小。(4)不同植物孢子有着各自最适的萌发培养基条件,如不同种类孢子对MS培养基中无机盐含量、蔗糖含量、pH值的要求不同。孢子外被中的Ca2+、Mn2+和Mg2+,培养基中的Cd2+和La3+,以及孢子接种密度、萌发空间CO2含量也会对孢子萌发造成影响。(5)多数蕨类植物孢子在15-30℃可以萌发,最适萌发温度为25℃。(6)4℃和液氮储藏可以延长孢子寿命并保持较高萌发率。     

苍耳柄锈菌三裂叶豚草专化型冬孢子萌发过程及萌发条件的研究

本文采用光学显微镜和扫描电子显微镜技术及荧光染色技术,对苍耳柄锈菌三裂叶豚草专化型Puccinia xanthii sp.ambrosiae-trifidae冬孢子的萌发过程和萌发条件进行了研究。结果表明:冬孢子堆成熟时突破寄主表皮外露;在寄主上冬孢子萌发时由上细胞顶部出现皱褶和帽状物,由帽状物下伸出担子。冬孢子的上细胞和下细胞都可萌发;冬孢子在水中于25℃2h即可萌发,24h后达到萌发高峰,萌发率为12%;温度20-25℃、相对湿度97%以上、pH5-7的条件利于冬孢子萌发,光照对冬孢子萌发没有影响,木糖和乳糖对冬孢子萌发有促进作用;无机氮源营养对冬孢子萌发有抑制作用。肌醇、烟酸、核黄素及三裂叶豚草叶汁对冬孢子萌发有促进作用。     

黄檗鞘锈菌担子发育及担孢子萌发的细胞学研究

为了解黄檗鞘锈菌Coleosporium phellodendri担子发育及担孢子萌发的细胞学变化,采用光学显微镜观察了冬孢子萌发、担子发育及担孢子萌发过程,并利用苏木精染色法对冬孢子萌发过程中细胞核的变化进行了研究。结果表明:未成熟的冬孢子含有两个细胞核,成熟时冬孢子伸长,两个细胞核融合成为1个核;冬孢子萌发时,中间形成一隔膜,将冬孢子分成两部分,上部分含金黄色的原生质体,下部呈透明的柄状结构;上部分发育形成4个细胞的内担子,然后发育形成担孢子。担孢子萌发时,产生1个芽管,顶端形成外观上与担孢子形态大小基本一致的次生孢子。次生孢子萌发产生芽管,形成菌丝。有极个别的次生孢子可再次形成次生孢子。冬孢子和担孢子在5–25℃温度范围内均能萌发,其中以15–25℃为适宜萌发的温度范围。     

粗茎鳞毛蕨孢子萌发研究

以经过3年低温储藏的粗茎鳞毛蕨孢子为实验材料,从孢子离心、孢子消毒、培养基种类、光质等4方面对孢子萌发进行研究,结果表明:在离心转数≤14 000 r.min-1、离心时间≤30 min条件下,离心处理对孢子萌发基本无影响;对孢子进行1%NaClO水溶液浸泡处理20～30 min为最佳消毒条件;改良Knop’s培养基为最佳孢子萌发培养基;黑暗条件下孢子不能萌发,但是黑暗处理能够明显提高孢子萌发整齐性;红光比白光能促进孢子提早萌发1 d左右,但对提高萌发率效果不显著。     

光照和温度对扇蕨孢子萌发的影响

用组织培养法和光学显微镜技术初步研究光照和温度影响扇蕨孢子萌发的结果表明,扇蕨孢子发芽是需光型,具有明显的光休眠现象。光照是孢子萌发的主要影响因子,25℃下,孢子萌发率达（85．1±5．1）％。相同温度下孢子即使在黑暗中培养50d也不能萌发,转入光照下后萌发率可达（82．4±6．6）％。孢子在光下的最适发芽温度为21．6-26．5℃,7d开始萌发,6-7周完全萌发,温度升高或下降均降低孢子萌发率。     

养分浓度和光照强度对泥炭藓有性更新的影响

作为优势植物, 泥炭藓(Sphagnum)在泥炭沼泽中缺乏有性更新的原因尚不清楚。针对影响孢子萌发的光强和养分条件, 以泥炭藓(S. palustre)为材料, 通过室内孢子萌发实验, 研究不同光强和养分浓度对孢子萌发率、萌发势及萌发指数的影响。4 种培养基中, 养分浓度高的营养液培养基中孢子萌发率最高, 达到60%, 其次为养分浓度与营养液相近的琼脂+营养液培养基, 萌发率为48%, 再次为养分水平很低的沼泽水培养基, 萌发率约为30%, 几乎无养分的蒸馏水培养基中萌发率最低, 约为5%。萌发势和萌发指数亦呈现相同的规律。琼脂+营养液和营养液培养基较沼泽水和蒸馏水培养基孢子萌发时间提前约3 天时间。增加光强使孢子萌发率仅提高10%。研究表明, 低养分浓度和弱光照均不利于孢子萌发, 相对而言, 泥炭沼泽的贫营养特征应是限制泥炭藓有性更新的更重要因素。     

芽孢杆菌孢子萌发机理的研究进展

芽孢杆菌休眠孢子的萌发是孢子恢复到营养生长的第一个决定性步骤。孢子被营养性萌发剂和各种非营养信号诱导而萌发恢复到营养细胞状态。芽孢萌发后就丧失了对外界胁迫的抵抗力。该文主要从芽孢萌发信号传导、营养萌发受体、萌发中的离子通道、皮层溶解酶的功能、非营养诱导萌发和萌发途径等方面阐述芽孢杆菌孢子萌发机理的进展,并对其前景作了简要评述。     

缩球囊霉孢子萌发及细胞核在孢子和芽管中分布的研究*

本文研究了从本校分离的丛枝菌根真菌缩球囊霉Glomus constrictum的孢子萌发和萌发孢子的细胞核DAPI(46-diamidino-2-phenylindol)染色。结果显示,G. constrictum孢子直径为179.5-198.7μm ,顶生于产孢菌丝上。经表面消毒处理后,孢子在水琼脂平板上7天开始萌发。DAPI染色后,经稀释荧光计数,单个孢子细胞核数目约为5300,在孢子中无序分布, 细胞核直径约为9.9-11.2μm 。孢子萌发过程中,细胞核总数无明显变化,只是部分细胞核从孢子流向了萌发伸长的菌丝。     

环境因子对中华双扇蕨孢子萌发的影响

为了解珍稀濒危植物中华双扇蕨(Dipteris chinensis)濒危原因,研究了温度和湿度对其孢子萌发的影响.结果表明,中华双扇蕨孢子萌发能力较强,萌发方式为Vittaria型,配子体萌发为Marattia型.中华双扇蕨孢子繁殖不受温度影响,而湿度显著影响孢子繁殖过程,湿润环境中孢子正常萌发,并形成心形配子体,顺利...     

小麦条锈菌CY32夏孢子萌发研究

研究夏孢子萌发过程的分子机制对于从分子水平上理解条锈菌的侵染过程及其与寄主互作的关系具有重要的理论意义。本研究以小麦条锈菌Pucciniastriiformisf.sptritici32号生理小种(CY32)为材料,研究了用水培方法萌发夏孢子的适宜条件。结果显示,CY32夏孢子萌发的最适温度为9℃,最适宜的孢子量是6mg/200mL水,适宜的溶液是无菌蒸馏水。水化能促进夏孢子的萌发,新鲜夏孢子和干燥容器中放置2d的夏孢子经水化15h后,萌发率显著提高。此方法获得的萌发夏孢子提取的RNA可以满足cDNA文库构建和基因表达分析等分子生物学研究的要求,并为小麦条锈菌的分子生物学研究奠定了物质基础。     

Moments of weaknesses – exploiting vulnerabilities between germination and encystment in the Phytomyxea

Attempts at management of diseases caused by protozoan plant parasitic Phytomyxea have often been ineffective. The dormant life stage is characterised by long-lived highly robust resting spores that are largely impervious to chemical treatment and environmental stress. This review explores some life stage weaknesses and highlights possible control measures associated with resting spore germination and zoospore taxis. With phytomyxid pathogens of agricultural importance, zoospore release from resting spores is stimulated by plant root exudates. On germination, the zoospores are attracted to host roots by chemoattractant components of root exudates. Both the relatively metabolically inactive resting spore and motile zoospore need to sense the chemical environment to determine the suitability of these germination stimulants or attractants respectively, before they can initiate an appropriate response. Blocking such sensing could inhibit resting spore germination or zoospore taxis. Conversely, the short life span and the vulnerability of zoospores to the environment require them to infect their host within a few hours after release. Identifying a mechanism or conditions that could synchronise resting spore germination in the absence of host plants could lead to diminished pathogen populations in the field.     

全白绒泡菌部分生活史图解

为深入了解全白绒泡菌生活史过程,对其孢子萌发、黏变形体和游动胞的相互转变、游动胞在5 s内的运动轨迹及原质团形成孢囊的过程进行了显微镜下观察和拍照,并对部分生活史阶段进行了时间测定,提出黏菌孢子萌发的第三种方式,提供了清晰的全白绒泡菌部分生活史的图片。     

Summer meeting 2013 – when the sleepers wake: the germination of spores of Bacillus species

Spores of Bacillus species can remain dormant and resistant for years, but can rapidly ‘come back to life’ in germination triggered by agents, such as specific nutrients, and non‐nutrients, such as CaDPA, dodecylamine and hydrostatic pressure. Major events in germination include release of spore core monovalent cations and CaDPA, hydrolysis of the spore cortex peptidoglycan (PG) and expansion of the spore core. This leads to a well‐hydrated spore protoplast in which metabolism and macromolecular synthesis begin. Proteins essential for germination include the GerP proteins that facilitate germinant access to spores' inner layers, germinant receptors (GRs) that recognize and respond to nutrient germinants, GerD important in rapid GR‐dependent germination, SpoVA proteins important in CaDPA release and cortex‐lytic enzymes that degrade cortex PG. Rates of germination of individuals in spore populations are heterogeneous, and methods have been developed recently to simultaneously analyse the germination of multiple individual spores. Spore germination heterogeneity is due primarily to large variations in GR levels among individual spores, with spores that germinate extremely slowly and termed superdormant having very low GR levels. These and other aspects of spore germination will be discussed in this review, and major unanswered questions will also be discussed.     

温度、相对湿度和pH对蜜蜂球囊菌孢子萌发的影响

研究了温度、相对湿度和pH对蜜蜂球囊菌(Ascosphaeraapis)孢子萌发3个阶段(活化、膨大、产生萌发管)的影响．结果表明,孢子活化和膨大在15～40和(25～40)±0．5℃范围内受温度的影响不明显(P＞0．05);萌发管仅发生在25～37±0．5℃,最适温度位于(31～35)±0．5℃．相对湿度越大,越有利于孢子萌发,而相对湿度低于80％对孢子萌发极为不利．孢子萌发的3个阶段在pH为5～7．8时几乎不受pH变化的影响,而在pH值较低影响很大．可见,A．apis是一种高度专一的蜜蜂幼虫病原体．     

Life cycle and morphology of Physarum pusillum (Myxomycetes) on agar culture

Myxomycetes (slime molds) are unique eukaryotic microorganisms with both characteristics of fungi and amoebae. Artificial cultures grown under controlled conditions were used to study the life cycle and morphogenesis. Physarum pusillum was collected from the field. Spores were inoculated and cultured with the hanging drop method. The complete life cycle was observed from spore to spore on agar without adding any solid nutrients or bacteria as food. Life cycle morphological characteristics were described for spore germination, myxamoebae, zygote, plasmodium and sporangia formation.     

Protein and Ribonucleic Acid Synthesis During the Diploid Life Cycle of Allomyces arbuscula

The diploid life cycle of Allomyces arbuscula may be divided into four parts: spore induction, germination, vegetative growth, and mitosporangium formation. Spore induction, germination, and mitosporangium formation are insensitive to inhibition of actinomycin D, probably indicating that stable, pre-existing messenger ribonucleic acid (RNA) is responsible for these developmental events. Protein synthesis is necessary during the entire life cycle except for cyst formation. A system for obtaining synchronous germination of mitospores is described. During germination there is a characteristic increase in the rate of synthesis of RNA and protein although none of the other morphogenetic changes occurring during the life cycle are necessarily accompanied by an appreciable change in the rate of macromolecular synthesis.     

Glucose-induced pathways for actin tyrosine dephosphorylation during Dictyostelium spore germination

In the presence of germination signals, dormant spores of Dictyostelium discoideum rapidly germinate to start a new life cycle. Previously we have shown that half of the actin molecules in spores are maintained in a tyrosine-phosphorylated state, and a decline of the actin phosphorylation levels is a prerequisite for spore swelling. In this study, we have established d-glucose as a trigger molecule for the actin dephosphorylation. Present in a nutrient germination medium, d-glucose both may act as a trigger molecule and/or may serve as a substrate within a pathway for actin dephosphorylation depending upon spore age. However, the glucose-induced actin dephosphorylation was insufficient for spores to swell. Other factors in the nutrient medium were required for complete germination of young spores aged 1 to 5 days. In contrast, dispersion in nonnutrient buffer was necessary and sufficient for a decline of actin phosphorylation levels and even the emergence of amoebae in older spores (6 days and beyond). Moreover, the dephosphorylation pathway in the older spores was independent of energy production. We propose that the diversification of the actin dephosphorylation pathway may enable spores to increase their probability of germination upon spore aging.