日本菟丝子及其寄生前后寄主的光合特征

对日本菟丝子与寄主的光合生理特征研究结果表明:日本菟丝子光合色素含量与寄主光合色素含量呈负相关.被日本菟丝子寄生后,易寄寄主寄生叶和相邻叶的光合色素含量增加,而非易寄寄主寄生叶和相邻叶的光合色素含量下降;非易寄寄主和易寄寄主的寄生叶和相邻叶净光合速率下降的幅度大小与寄主受日本菟丝子易寄程度的强弱顺序一致,前者净光合速率下降主要是由气孔调节引起的,而后者则是多因素共同调节的结果.在光照条件下,与非易寄寄主相比,日本菟丝子从易寄寄主上脱离后的光合色素含量随光照时间的延长而增加,其干质量则下降减缓;黑暗条件下,日本菟丝子从不同寄主脱离后的光合色素含量与干质量下降速率的差异不显著.     

不同光照及赤霉素处理对菟丝子寄生关系建立的影响

首次使用LED作为光源,研究不同光照条件及GA3对菟丝子(Cuscuta spp.)弯钩打开、缠绕发生与吸器形成的影响.结果表明,光照信号作为一个必要条件参与了菟丝子对寄主的识别及缠绕发生的调控,而化学信号可能起到一定的促进作用;GA3参与了对菟丝子缠绕发生的调控,但对弯钩打开没有明显的作用.除了典型的光敏色素作用外,还有另一类光反应(HER)参与了上述过程,这类光反应可由879 nm远红光引发,证明菟丝子存在HER,还有Pfr向Pr的暗转化过程,在缠绕发生过程中光敏色素和隐花色素发生相互作用.     

田野菟丝子寄生薇甘菊的形态解剖学研究

采用扫描电镜及光镜观察田野菟丝子——薇甘菊茎的全寄生系统建立的过程.根据对吸器发生发育的观察,将其发育过程划分为4个阶段:接触反应、吸附作用、侵入生长及维管系统的建立.田野菟丝子的寄生吸器由吸器原基发育而来;当田野菟丝子成功吸附到可寄生寄主时,两者间的接触面会积累一些分泌物;吸器原基继续发育为内生原基,侵入寄主植物后单...     

小麦条锈菌吸器母细胞入侵菌丝现象的进一步研究

应用电镜技术对小麦条锈菌吸器母细胞入侵自身菌丝的现象进行了研究,观察发现,在吸器母细胞与寄主细胞和菌丝细胞同时相接触的情况下,入侵栓可在与寄主细胞接触处形成,也可在与菌丝接触处形成;在菌落中心部位,吸器母细胞虽然未与寄主细胞接触,但同样可在与菌丝细胞接触处产生入侵栓;吸器母细胞在与菌丝接触处形成的人侵栓,其超微结构正常,并且可侵入到菌丝细胞壁内,但是未能穿透菌丝细胞壁。本文观察结果表明,小麦条锈菌吸器母细胞和人侵栓形成所需诱导因子可能是物理接触作用,而不涉及到化学作用,并且该病菌与寄主间的识别作用可能发生在入侵栓形成之后。     

小麦叶锈菌侵染过程的显微和超微结构

采用光学显微技术和电子显微技术对小麦叶锈菌的侵染过程进行了研究。发现叶锈菌从气孔侵入后在气孔腔内形成气孔下泡囊,然后分化出圆形的膨大体,由膨大体产生1—2初生菌丝,初生菌丝在寄主细胞间隙延伸扩展,与叶肉细胞壁接触后分化形成吸器母细胞,吸器母细胞进入寄主细胞后形成吸器。初生菌丝在吸器母细胞处产生分枝,形成次生菌丝在叶肉细胞间蔓延。在病原菌侵染早期(接种后8—24h),寄主细胞的超微结构变化并不明显。侵染中、后期(接种48—72h),被侵染叶肉细胞发生严重质壁分离,叶绿体膨胀变形,基粒片层排列疏松。线粒体嵴突退化。     

日本菟丝子寄生菌致病力的专化性研究

日本菟丝子(Cuscuta japonica)吸取不同寄主植物的营养,经过营养代谢其机体内的过氧化物酶同工酶的活性或酶带数发生变化,从而改变了它对胶孢炭疽菌菟丝子专化型[Col-letotrichum gloeosporioides(Penz.)Sacc.f.sp.Cuscutael]同一菌株的抗性,以此为依据,采用寄生在不同植物上的日本菟丝子做为鉴定寄主,可以鉴别出胶孢炭疽菌菟丝子专化型中不同菌株的致病力差异。 初步认为:龙眼、桂花、柚子和冬青上的紫色菟丝子及泡桐、桂花和冬青上的黄色菟丝子可以作为鉴定寄主。     

小麦条锈菌吸器母细胞入侵菌丝现象的进一步研究

应用电镜技术对小麦条锈菌吸器母细胞入侵自身菌丝的现象进行了研究。观察发现,在吸器母细胞与寄主细胞和菌丝细胞同时相接触的情况下,入侵栓可在与寄主细胞细胞接触处形成,也可在与菌丝接触处形成;在菌落中心部位,吸器母细胞虽然未与寄主细胞接触,但同样可在与菌丝细胞接触处产生入侵栓;吸器母细胞在与菌丝接触处形成的入侵栓,其超微结构正常,并且可侵入到菌丝细胞壁内,但是未能穿透菌丝细胞壁。本文观察结果表明,小麦条     

基质养分对寄生植物南方菟丝子生长的影响

群落中各营养级的相互作用在群落结构形成中起了重要作用.以南方菟丝子(Cuscuta australis R.Br.)和三叶鬼针草(Biden pilosa L.)为研究对象,采用完全随机区组实验设计方法,测定并分析基质养分(不施肥与施肥)对寄生植物生长的影响,探讨寄生植物生物量与寄主生长特性、生物量和光源捕获能力的相关性.结果表明,施肥显著增加寄生植物南方菟丝子的吸器数量、缠绕圈数、相对盖度、营养器官生物量、生殖器官生物量和总生物量,但对生殖器官的生物量比无显著影响.施肥显著增加寄主植物的根、茎、叶生物量和总生物量、叶生物量比、比叶面积和叶绿素含量,但显著降低根冠比与根生物量比.南方菟丝子生物量与三叶鬼针草生物量、叶生物量比、比叶面积以及相对叶绿素含量之间均存在显著正相关,与根生物量比和根冠比存在显著负相关.研究结果表明施肥可以提高寄主植物的光资源捕获能力,将更多地生物量分配至叶等光合机构上,从而促进寄主植物(生产者)的生长,并间接促进寄生植物(初级消费者)的生长.     

檀香与不同豆科植物寄生关系的研究

为了解檀香(Santalum album L.)与不同豆科植物的寄生关系,选取11种具有重要经济价值的豆科植物和檀香一起种植,对檀香叶片的光合特征和株高、地径以及寄主植物根系的吸器大小进行了测定。结果表明,檀香的吸器大小、数量在不同寄主之间存在很大差异,不同寄主对檀香的株高、地径也有显著差异。檀香的优良寄主有美洲合欢(Calliandra haematocephala)、苏木(Caesalpinia sappan)、台湾相思(Acacia confusa)、龙牙花(Erythrina corallodendron);一般的寄主植物有马占相思(Acacia mangium)、降香黄檀(Dalbergia odorifera)、黄槐(Cassia surattensis);不适宜的寄主植物有凤凰木(Delonix regia)、海南红豆(Ormosia pinnata)、银合欢(Leucaena leucocephala)、洋紫荆(Bauhinia blakeana)。同时,檀香的株高、地径及光合特征和吸器数量密切相关。因此,檀香种植时应选择适宜的优良寄主植物。     

种衣剂17号包衣对小麦条锈菌发育影响的超微结构研究

本研究采用电镜种衣剂１７号泽小麦条锈菌发育的影响。观察结果表明,该种衣剂引病菌和寄主细胞内发生了一系列变化。病菌菌丝和吸器内脂肪粒和液泡明显增加;菌丝壁和吸器壁呈不规则加厚;菌丝分枝处玩隔膜产生或隔膜畸形;有的吸器母细胞产生的畸形人侵栓,大都不能穿管寄主细胞壁,初生吸器外音质同内沉积有染色较深的物质,次生吸器可产生多个不规则分枝,但不能扩张膨大,菌丝外渗的物质可能引起寄主细胞的坏死;大多数受侵寄主     

四种与福寿螺(Ampullaria gigas)同源地入侵植物的杀螺效果

实验室内观察了福寿螺在其主要危害对象水稻,及与其同源地的入侵植物五爪金龙、马缨丹、胜红蓟和蟛蜞菊５种植物新鲜叶片间聚集数量差异,结果显示:15min后福寿螺在距离其约75cm 的5种植物叶片聚集数产生了显著的差异,但75min内福寿螺在5种植物叶片间聚集的数量不稳定,75min后的聚集数趋于稳定,5种植物叶片上聚集福寿螺数由多到少顺序为蟛蜞菊、马缨丹、水稻、胜红蓟和五爪金龙。福寿螺取食水稻幼苗的量较大,显著高于取食另4种植物新鲜叶片的量,福寿螺取食4种与其同源地植物叶片量由小到大的顺序为：五爪金龙、蟛蜞菊、胜红蓟和马缨丹。不同浓度4植物乙醇提取物水溶液对福寿螺毒杀作用差异显著,乙醇提取物饱和水溶液致福寿螺100%死亡的时间由短到长的顺序为：五爪金龙48h, 蟛蜞菊72h, 胜红蓟和马缨丹均为96h,按常规施用量化学农药密达100%毒杀福寿螺的时间为118h。综合结果表明五爪金龙具有开发出既能有效防治福寿螺又不影响水稻生长和稻田环境材料的潜力。     

嗅觉和视觉在中华微刺盲蝽对马缨丹定向行为中的作用

对马缨丹(Lantana camara)、黄花马缨丹(Lantana camara cv.‘Flava')和紫花马缨丹(Lantanamontevidensis)花序上中华微刺盲蝽(Campylomma chinensis)的密度调查结果表明,中华微刺盲蝽在3种颜色马缨丹花序上的分布与花序颜色无关(偏相关系数为0.240,P=0.147,n=40),但与花序中的黄胸蓟马数量和花序中小花数的偏相关系数分别为0.512(P＜0.0001,n=0)和0.451(P＜0.0001,n=40),达到极显著水平.中华微刺盲蝽对不同颜色粘卡的试验也表明,该盲蝽寻找植物寄主时,视觉刺激并不起作用.四臂嗅觉仪的试验结果表明,中华微刺盲蝽对马缨丹的气味有强烈的趋向作用.采用固相微萃取和气相-质谱联用技术分析表明,3种马缨丹花序的挥发物有7种相同的化学成分.     

守瓜属甲虫的取食行为与寄主植物葫芦素种类的关系

黄足黄守瓜和黄足黑守瓜是两个非常相似的守瓜属甲虫,但它们对寄主的选择性和取食行为却完全不同.黄足黄守瓜先用口器在黄瓜或南瓜叶面划圈,然后取食圈内叶组织,但却不取食丝瓜、苦瓜和西瓜,而黄足黑守瓜则只取食丝瓜,且不发生划圈取食行为.研究表明,这两种甲虫的寄主选择性及取食行为与瓜类作物合成的葫芦素种类显著相关.黄瓜和南瓜在黄足黄守瓜取食后能诱导合成抑制取食的葫芦素Ⅰ,使得黄守瓜只能先划圈阻断葫芦素Ⅰ在叶面的迁移才能取食圈内叶组织.而苦瓜和西瓜本身就合成抑制取食的葫芦素D,使得甲虫不选择这两种瓜类作物取食.丝瓜则合成刺激甲虫取食的葫芦素B和E,使得黑守瓜能直接取食.本研究表明,守瓜属甲虫对寄主植物合成的特定次生物质的味觉响应机制在其寄主选择和取食行为方面起着重要作用.     

Effects of indole-3-acetic acid on Botrytis cinerea isolates obtained from potted plants

We study the growth of different isolates of Botrytis cinerea collected from potted plants which were affected by Botrytis blight in southern Spain during recent years. These isolates, which show widely phenotypic differences when grown in vitro, are differentially affected by growth temperature, gibberellic acid applications and paclobutrazol, an efficient plant growth retardant and fungicide at the same time. In this work, we have evaluated the effect of the auxin indole-3-acetic acid (IAA) dose (0, 1, 10, and 100 mg/plate) on the growth of the collection of B. cinerea isolates obtained from the following potted plants: Cyclamen persicum, Hydrangea macrophylla, Lantona camara, and Lonicera japonica. B. cinerea produces indolacetic acid, but so far the precise biosynthetic pathway and some effects on this fungal species are still unclear, although recent studies have revealed an antifungal activity of IAA on several fungi, including B. cinerea isolated from harvested fruits. Mycelial growth curves and growth rates assessed from difference in colony areas during the both linear and deceleration phase, conidiation (measured as time of appearance), conidia length (microm), and sclerotia production (number/plate) were evaluated in the isolates, which were grown at 26 degrees C on Petri dishes containing potato dextrose agar for up to 35 days. Mycelial growth curves fitted a typical kinetic equation of fungi grown on solid media. B. cinerea isolates showed a high degree of variability in their growth kinetics, depending on the isolate and auxin dose. This plant growth substance delayed mycelial growth during the linear phase in an isolate-dependent manner, thus isolates from C. persicum, H. macrophylla and L. camara were more affected by IAA than L. japonica. On the other hand, 100 mg of IAA was the critical dose to significantly reduce the growth rate in all isolates and to promote brown-striped hyphae development, especially in isolate from C. persicum. 10 and 100 mg IAA delayed conidiation in isolates from H. macrophylla but scarcely effects were found in the conidia length. The sclerotia production process was blocked at IAA doses of 100 mg in isolates from L. camara and L. japonica, and was reduced in isolate from H. macrophylla. However, dose of 100 mg IAA had no effect on sclerotia production in isolate from C. persicum. It was concluded that the effect of IAA on B. cinerea growth depends on the isolate, thus isolates from H. macrophylla and L. camara were the most affected by IAA. B. cinerea reduced its development under IAA applications, depending on the isolate and dose. These results confirm those recently published on the inhibitory effect of IAA on Botrytris species growth.     

Seed Dispersal by a Frugivore Pycnonotus sinensis and the Distribution of Sambucus chinensis

Frugivorous birds play an important role in the distribution of those plants on whose fruits they feed and affect species composition of plant communities. The fruiting phenology of Sambucus chinensis Lindl. in Wuhan area ranges from July to November, while abundant fruits are available in July and August. Although other seven species of frugivores were found in the study area, only Pycnonotus sinensis (Gmelin), a resident bird endemic to China, was observed foraging in the fruits of this plant for the field. Pycnonotus sinensis shifts from eating fruits of Broussonetia papyrifera (L.) Vent. to those of S. chinensis from July to August. Identification of seeds in a total of 658 feces disseminated by P. sinensis which were collected in the field showed that most of the seeds came from S. chinensis and B. papyrifera. Seeds in those feces collected at the end of August were all of S. chinensis. Field investigation of the associations of S. chinensis shows that its frequent companion species are B. papyrifera, Cinnamomum camphora, Ligustrum lucidum and Rubus biflorus, whose fruits are also preferred by this frugivore in different seasons. The distribution of Pycnonotus sinensis is limited to the south of Qinling Mountain in China. The distribution of S. chinensis is basically consistent with that of Pycnonotus sinensis. The result indicates that seed dispersal of S. chinensis depends on the foraging of this frugivore. Likewise, the fruits of S. chinensis are the primary food for this frugivore in autumn. As the result suggests, conservationists and restoration biologists should highlight the study of plant-disperser mutualism in the future work.     

Mechanism of parasitization by Cuscuta reflexa: RNase activity in the haustorial region of Cuscuta and infected host tissues

In a study of host-parasite interrelationship and the mechanism of parasitization, ribonuclease activity was determined in Cuscuta reflexa Roxb, and in infected and control host plants of Lantana camara L. In the haustoria-bearing region of Cuscuta , the concave half of the vine bearing the haustorial site, always showed significantly higher RNase activity than the convex half, irrespective of the differing enzyme activity of the parasite tissue growing on different hosts — Brassica campestris L., Helianthus animus L., Lantana camara L., Medicago saliva L. and Solatium nigrum L. The uninfected host branch of L. camara showed the maximum specific RNase activity in the apical region which decreased toward the base, while the infected host branch showed minimum specific RNase activity in the apical region, gradually increasing towards the infected region.     

山稻蝗不同地域种群染色体C带核型研究

对我国分布的山稻蝗OxyaagavisaTsai不同种群进行了染色体C带核型研究 ,并对山稻蝗武夷山种群染色体C带核型进行了深入探讨 ,分析了其带型特殊性及该种群与其它山稻蝗种群染色体C带核型的区别与联系。同时通过对山稻蝗与中华稻蝗Oxyachinensis (Thunberg)、日本稻蝗Oxyajaponica (Thunberg)的形态、分布及染色体C带核型等方面的比较 ,探讨了该 3个种之间的进化关系 ,认为作为稻蝗属中的大型种类 ,上述 3个种之间有着较近的亲缘关系。染色体带型的实验结果表明 ,中华稻蝗为较原始的种类 ,而日本稻蝗和山稻蝗则可能是由原始中华稻蝗进化而来 ,其中日本稻蝗L2染色体的形成是由于原始中华稻蝗该染色体常染色质部分异染色质化的结果 ,山稻蝗L2染色体则可能是由于原始中华稻蝗该染色体近端部的臂间倒位所致。通过对武夷山山稻蝗的研究 ,对日本稻蝗和山稻蝗之间的近缘关系进行了分析和讨论。     

食果鸟白头鹎与接骨草的分布

作为种子的传播者 ,以果实为生的动物在所食植物的繁殖周期中起着关键作用。尽管动植物相互作用的研究自达尔文开始就引起了进化生物学家和生态学家的关注 ,但和传粉者与植物的相互作用的研究相比 ,种子传播者与植物相互作用的研究在 2 0世纪 70年代后才真正开始[1] 。植物学家     

Structure and development of the upper haustorium in the parasitic flowering plant Cuscuta japonica (Convolvulaceae)

The anatomical and ultrastructural development of the haustorium of the Cuscuta japonica, a holoparasitic angiosperm, growing on the host plant Impatiens balsamina was studied. After the shoot tips of light-grown parasite seedlings contacted the host, the upper haustorium (external to the host organ) developed through three main successive stages of the haustorial initials, the meristem, and the endophyte primoridium (EP) within the middle layer of the cortex of the parasite stem. The haustorial initial cells were characterized by abundant starch-bearing amyloplasts and mitochondria with an expanded intermembrane space. The meristem cells had numerous large chloroplasts with well-developed thylakoids, reflecting the capability for photosynthesis. Commonly, all three stages of haustorial cells contained conspicuous, large nuclei with enlarged nucleoli and dense cytoplasm including many other organelles, indicating a very active metabolism. In the final stage of upper haustorium development, the meristem cells differentiated into the EP, a host-penetrating tissue. The primordium had smaller file cells at the proximal end and elongate digitate cells at the distal end. The file cells divided actively, while the digitate cells contained abundant chloroplasts, dictyosomes, rough endoplasmic reticulum, and other organelles, suggesting that the EP was cytohistologically well organized for penetration into the host tissue.     

Circumnutation behavior of an exotic honeysuckle vine and its native congener: influence on clonal mobility

Virtually all plant parts rotate slightly about a central axis, a movement called circumnutation, but vines show exaggerated circumnutation. This study contrasts circumnutation in two congeneric twining vines, specifically focusing on differences in erect and prostrate shoots, and examines the impact of circumnutation on exploitation of available climbing supports and exploration for more distant ones. Elongating shoots of Lonicera japonica and L. sempervirens growing in a common garden were classed as (1) erect but not climbing, (2) climbing on a trellis, or (3) prostrate, and their circumnutation quantified by tracking the compass direction of shoot tips. To quantify the impact of different circumnutation behaviors, the climbing success of erect shoots and the maximum dispersion and rooting success of prostrate shoots were measured. Erect shoots of both species circumnutated at similar rates (averaging 31°/h), and did not differ in their success rate of exploiting trellises (averaging 76.8%). Prostrate shoots differed, with those produced by L. japonica having reduced circumnutation. In contrast, prostrate shoots of L. sempervirens continued to circumnutate as much as erect shoots. The specialized circumnutation behavior of the prostrate shoots of L. japonica results in increased rooting success and maximum dispersion compared to the unspecialized shoots of L. sempervirens.