中国特有蕨属扇蕨属（水龙骨科）的系统学研究

扇蕨属（Neocheiropteris）为中国蕨类植物4个特有属之一。自Christ建属以来,不同的分类学者对本属的范畴以及系统位置一直存有争议。本研究对扇蕨属和盾蕨属进行了形态解剖观察,并对扇蕨属及其近缘类群共14个种的4个叶绿体DNA片段：rbcL、rpS4 ＆ rpS4-trnS IGS、trnL intron ＆ trnL-trnF IGS以及atpB ＆ atpB-rbcL IGS进行测序,应用最大简约法（Maximum-parsimony）、最大似然法（Maximum-likeli-hood）和贝叶斯推断（Bayesian inference）对序列进行联合矩阵分析,并构建系统树。该研究从形态学和分子系统学方面都提出了支持扇蕨属和盾蕨属分立的证据。形态学研究显示扇蕨属和盾蕨属叶片分裂方式、叶被和侧脉特征迥异,支持扇蕨属和盾蕨属的分立;但两属根状茎鳞片的共同特征则反映了两属问的紧密联系。分子系统学研究表明扇蕨属与毛鳞蕨属和鳞果星蕨属构成姐妹群,其集合与盾蕨属构成姐妹群。综合形态学和分子系统学的证据,对扇蕨属的系统位置以及范畴进行了深入探讨,扇蕨属包括扇蕨和三出扇蕨,结合形态学和分子系统学证据对三出扇蕨的系统位置进行了初步探讨。     

The Physiology of Adventitious Roots

Adventitious roots are plant roots that form from any nonroot tissue and are produced both during normal development (crown roots on cereals and nodal roots on strawberry [Fragaria spp.]) and in response to stress conditions, such as flooding, nutrient deprivation, and wounding. They are important economically (for cuttings and food production), ecologically (environmental stress response), and for human existence (food production). To improve sustainable food production under environmentally extreme conditions, it is important to understand the adventitious root development of crops both in normal and stressed conditions. Therefore, understanding the regulation and physiology of adventitious root formation is critical for breeding programs. Recent work shows that different adventitious root types are regulated differently, and here, we propose clear definitions of these classes. We use three case studies to summarize the physiology of adventitious root development in response to flooding (case study 1), nutrient deficiency (case study 2), and wounding (case study 3).     

栝楼不定根尖分化不定芽过程中的细胞组织学研究

将栝楼（Trichosanthes kirilowii)长约0.5-1cm不定根尖（连同原外植体茎段或根段一起,或不连）培养在MS附加6－BA5mg/L的培养基上光照培养15d,可在根尖分化出大量不定芽。不定根尖培养过程中每隔2－3d取材,用FAA固定液固定1次,通过石蜡切片观察,将栝楼的不定根尖端分化不定芽的细胞组织学变化分为4个时期。1．启动期（0-3d),根尖分生组织细胞、中柱鞘细胞起动分裂。2“根茎转变区”原形成层形成期（4－6d0。起动细胞分裂后形成2－3层体积小、核大、质浓、近似扁平形的细胞层,组成“杯形”的“根茎转变区”原形成层。3．“根茎转变区”形成期（7－10d)。原形成层不同部位加速分裂使根尖膨大成半球形、球形或梭形,并在膨大区进行维管组织的转变。4．芽分化形成期（11－15d)。原形成层在不同部位向外形成“突起”即分生细胞团,每个“突起”发育为1个芽原基。作者还讨论了栝楼与其它植物根芽产生的异同。     

Rediscovery of Polypodium calirhiza (Polypodiaceae) in Mexico

This study addresses reported discrepancies regarding the occurrence of Polypodium calirhiza in Mexico. The original paper describing this taxon cited collections from Mexico, but the species was omitted from the recent Pteridophytes of Mexico. Originally treated as a tetraploid cytotype of P. californicum, P. calirhiza now is hypothesized to have arisen through hybridization between P. glycyrrhiza and P. californicum. The tetraploid can be difficult to distinguish from either of its putative parents, but especially so from P. californicum. Our analyses show that a combination of spore length and abaxial rachis scale morphology consistently distinguishes P. calirhiza from P. californicum, and we confirm that both species occur in Mexico. Although occasionally found growing together in the United States, the two species are strongly allopatric in Mexico: P. californicum is restricted to coastal regions of the Baja California peninsula and neighboring Pacific islands, whereas P. calirhiza grows at high elevations in central and southern Mexico. The occurrence of P. calirhiza in Oaxaca, Mexico, marks the southernmost extent of the P. vulgare complex in the Western Hemisphere.     

江南星蕨配子体形态发育的研究

用无机培养基和土壤培养基分别培养江南星蕨(Microsorium fortunei(Moore)Ching)孢子,显微镜下观察记录其孢子萌发及配子体形态发育过程.结果表明:孢子黄色,赤道面观豆形,极面观椭圆形,单裂缝,外壁具刺状纹饰.接种后7～12d孢子萌发,萌发类型为书带蕨型,配子体发育为槲蕨型.接种后25 d左右发育为片状体,片状体形成顶端细胞的时间较晚,有的甚至不形成.无机培养基培养的原叶体常在基部发生营养繁殖.毛状体出现在片状体形成之后,数量丰富,多为单细胞,分布于原叶体背腹面及边缘.接种后60 d左右发育形成幼原叶体,成熟原叶体呈心脏形.接种后80 d左右开始有性器官出现,精子器的出现较颈卵器早10d左右.颈卵器成熟后,颈部常向原叶体基部倾斜或弯曲.     

隐子蕨属（水龙骨科）植物在中国的首次承认

首次承认水龙骨科（Polypodiaceae）隐子蕨属（Crypsinus）植物在中国的分布。文中列出了该属与假瘤蕨属（Phymatopteris）和修蕨属（Selliguea）的区别特征,给出隐子蕨属植物在中国的唯一一种——三指隐子蕨（Crypsinus trilobus）的文献引证,特征描述并附图。     

The Micronutrient Boron Causes the Development of Adventitious Roots in Sunflower Cuttings

Three-day-old light-grown sunflower seedlings were de-rootedand incubated in nutrient solutions that either contained orlacked boric acid (B). In the absence of B, in the majorityof the seedlings, no adventitious roots were formed. The micronutrientB caused the development of numerous roots in the lower partof the hypocotyl. The effect of B occurred without the supplyof any phytohormones. A dose-response curve of B-induced rootingyielded an optimum concentration of 0.1 mM boric acid. Histologicalstudies revealed that cell divisions occurred in the controlbut no root primordia developed. In cuttings that were incubatedin B (0.1 m M) root primordia were observed that rapidly developedinto well-differentiated adventitious roots. Sunflower cuttingsthat were planted with their cut end in vermiculite that wasmoistened with nutrient solutions without B degenerated afterseveral weeks. In the presence of B the cuttings formed numerousadventitious roots that entirely replaced the tap root systemof intact seedlings. The rooted cuttings developed into sturdyadult sunflower plants. Our results are discussed with respectto the possible role of B in the evolution of vascular fromprevascular plants.Copyright 1999 Annals of Botany Company Adventitious roots, boron, cuttings, organogenesis, sunflower seedlings.     

培养因子对艾西丝南瓜芽增殖及不定根形成的影响

以艾西丝南瓜带芽茎段为外植体 ,研究了基本培养基、激素、糖、光照、培养基支持物等因子对芽增殖及不定根形成的影响。结果表明 :艾西丝南瓜芽增殖的最佳培养条件为 :MS BA 0 .5～ 1 .0mg/L IAA 0 .1～ 0 .5mg/L 食用白糖 30g/L ,芽的月增殖系数稳定在 1 0左右 ;不定根诱导的适宜条件是 :1 /2MS 食用白糖 2 0g/L ,生根率达 86% ;且自然散射光条件 ( 1 0 0 0～ 50 0 0Lx)优于灯光 ( 1 0 0 0～2 0 0 0Lx) ;以脱脂棉作生根培养基支持物效果优于琼脂 ,其芽增殖系数和生根率分别提高 2 6%和 7%。     

Development of Lateral Primordia in Decapitated Adventitious Roots of Allium cepa

In decapitated adventitious roots of Allium cepa L. var. French,the time taken for lateral primordia to appear in five sectorshas been studied. This time is approx. 4–5 d after theapex of the adventitious root gave rise to the primordial initialcells. Allium cepa, adventitious root, lateral primordia     

中国节肢蕨属（水龙骨科）新资料

本文报道灰茎节肢蕨和片马节肢蕨前者是新组合的一种变种。同时也是中国和云南的新记录,后者是中国云南的一新变型。     

Development of mantle leaves inPlatycerium bifurcatum (Polypodiaceae)

InPlatycerium bifurcatum the leaf primordia emerge alternately right and left below the shoot apical cell on the dorsal surface of the rhizome. They arise from groups of small cells, a single large cell becoming the initial of the leaf apical cell. The longitudinal axis of the leaf apical cell is at a right angle to the rhizome axis and the leaf primordia are arranged longitudinally in two rows. The leaf apical cell gives rise to marginal initials which are responsible for leaf growth in one plain. Early marginal cells are crescent-shaped while the later ones are wedge-shaped. Hairy marginal cells appear in the very early stages of development. The interpretation of these cells as a promeristem and as initials are discussed.     

A Transmission and Cryo-Scanning Electron Microscopy Study of the Formation of Aerenchyma (Cortical Gas-Filled Space) in Adventitious Roots of Rice (Oryza sativa)

The initiation and development ofaerenchyma in adventitiousroots of rice (Oryza sativa) was studied in tissuc up to approximately36-h-old using transmission electron microscopy (TEM) and cryoscanningelectron microscopy (cryo-SEM). Aerenchyma resulting from selective cortical cell collapse isa naturally occurring feature of rice roots. Evidence of somecortical cell disruption was noticeable by TEM in cells thatwere approximately 6-h-old; it became more advanced as the cellsaged. At 12 h, early stages of cell wall breakdown and lossof cell turgidity were seen. Complete collapse of columns ofcells had occurred by 24 h. In tissue that was 36-h-old, thesenescent cytoplasm of many remaining cells began to disperse.The visual evidence suggests that cell collapse was the resultof autolysis. This pattern of cortical degeneration in ricewas dissimilar to that reported elsewhere for Zea roots grownin an oxygen depleted environment. Cryo-SEM revealed the occurrence of small structures withinthe cortex with the external appearance of miniature, intactcells which are not preserved during conventional SEM preparativeprocedures. Key words: Rice (Oryza sativa L.), roots, aerenchyma, ultrastructure     

Induction of a 'Periderm-like' Tissue in Excised Roots of the Fern Ophioglossum petiolatum Hook

Basal applications of plant growth regulators to excised rootsof Ophioglossum induce modifications in the outer cortical cells.Benzyladenine initiates periclinal divisions in these outercells producing a ‘periderm-like’ tissue while 2,4-Dcauses cell enlargement only. Walls of the outer cells of the‘periderm-like’ tissue are resistant to sulphuricacid and stain with Sudan IV and presumably are suberized.     

中国水龙骨属(水龙骨科)新资料

喜马拉雅水龙骨（西藏植物志）Ｐｏｌｙｐｏｄｉｏｄｅｓｈｅｎｄｅｒｓｏｎｉ（Ｂｅｄｄ．）Ｓ．Ｇ．Ｌｕ,ｃｏｍｂ．ｎｏｖ．———ＧｏｎｉｏｐｈｌｅｂｉｕｍｈｅｎｄｅｒｓｏｎｉＢｅｄｄｏｍｅ,ＦｅｒｎｓＢｒｉｔ．Ｉｎｄ．Ｓｕｐｐｌ．２１．ｐｌ．３８３．１８...     

小型生物反应器内人参不定根的人参皂苷累积

对小型生物反应器(3~10 L)培养人参不定根的生长和人参皂苷(Rg1、Re、Rb1)的累积规律,以及蔗糖浓度、初始接种量对其生长和人参皂苷累积的影响进行研究。结果表明:小型生物反应器内人参不定根的最佳收获周期为7周。初始接种量和蔗糖浓度影响生物反应器内人参不定根的生长和人参皂苷的累积,20或40 g/L蔗糖对人参不定根的生长和人参皂苷的累积优于60 g/L蔗糖;5和10 L生物反应器内最佳初始接种量分别为15和30g,其不定根的生长量分别为9.29和19.17 g,人参皂苷含量分别为5.16和4.58 mg/g。生物反应器内培养7周的人参与栽培4年的人参相比,人参皂苷Rg1和Re含量相差不大,但栽培人参中Rb1的含量远高于生物反应器中所培养的人参不定根。     

Adventitious embryony inNigritella (Orchidaceae)

The embryology of diploid and polyploidNigritella species is described. The development of the adventitious embryos of the polyploids in relation to the sexual embryos of the diploids has been given special consideration. Partial sexuality in the apomicticN. nigra has been proven for the first time by chromosome counts in proembryos after pollination of a tetraploid plant with pollen from a diploid species.     

The Role of Endogenous Auxins and Ethylene in the Formation of Adventitious Roots and Hypocotyl Hypertrophy in Flooded Sunflower Plants (Helianthus annuus)

The role of ethylene and auxins in flood-induced adventitious root formation and hypocotyl hypertrophy in sunflower (Helianthus annuus L. cv. Russian) plants was studied. Flooding without aeration (F) resulted in a steady increase in ethylene in hypocotyls, and flooding with aeration (FA) caused a transient increase. Low light intensity increased ethylene levels but decreased adventitious root formation. Treatment of shoots with benzyladenine (BA) increased ethylene content in non-flooded (NF) but not in F or FA shoots. Twenty-four hours of flooding brought about a rise of endogenous indole-acetic acid (IAA) in hypocotyls. ¹⁴C-IAA applied to the shoot accumulated more in F and FA hypocotyls than in NF hypocotyls, and BA reduced this accumulation. There was less IAA metabolism in F and FA than in NF hypocotyls. Tri-iodo benzoic acid (TIBA) applied to the hypocotyls of F plants inhibited root production. Benzyladenine (BA) applied to the leaves had similar effect but was not effective when supplied to the shoot apex. BA did not inhibit flood-induced hypocotyl hypertrophy. Ethrel did not affect adventitious root formation in NF plants but did increase hypocotyl thickening. It is concluded that flood-induced adventitious root formation is stimulated primarily by an accumulation of auxins in the hypocotyls. Increases in ethylene might cause this auxin build up. Hypocotyl hypertrophy is presently thought to be the result of an interaction of auxin and ethylene with ethylene being the major factor.     

The Role of Shikimic Acid in Waterlogged Roots and Rhizomes of Iris pseudacorus L.

Levels of shikimic acid in the roots and rhizomes of Iris pseudacorusgrowing under natural conditions were measured at monthly intervalsfor a period of one year. Seasonal fluctuations in the shikimatecontent suggest that the high levels during winter floodingand lower levels during the summer period of low water tableare related to a particular flood-tolerance metabolism in theroots and rhizomes. The suggested pathway, involving the condensationof phosphoenolpyruvate and crythrose 4-phosphato (both formedduring anaerobic carbohydrate breakdown) to 3-deoxy-D-arabino-heptulosouicacid 7-phosphate and the subsequent synthesis of shikimie acid,appears to function as a physiological adaptation to floodingin rhizomatous species such as I. pseuducorus. Other pathwaysof anaerobic respiration in waterlogged roots are discussedin relation to the proposed scheme in Iris.