STUDIES ON THE ULTRASTRUCTURE OF THE GUARD CELLS OF OPUNTIA

The guard cells of Opuntia contain numerous mitochondria, elements of endoplasmic reticulum, dictyosomes, and microbodies. A complex array of small to large vacuoles which contain small, membrane-bounded vesicles occur in each guard cell. The variety of cytoplasmic constituents and vacuoles suggest that the guard cells are complex in function. A highly reduced grana-fretwork system within the plastids indicates that the photosynthetic capacity of the guard cells is probably rather low. No plasmodesmata occur in the walls between the guard cells and the subsidiary cells while there are numerous invaginations of the guard cell plasmalemmas. Many of the variations in the plasmalemma probably indicate that the plasmalemma is a highly active interface.     

THE FINE STRUCTURE OF THE GUARD CELLS OF HELIANTHUS ANNUUS

The guard cells of Helianthus annuus contain elements of endoplasmic reticulum and large numbers of mitochondria and dictyosomes. Each guard cell possesses a complex system of small to large vacuoles which contain small, membrane-bound vesicles; the vacuole may actually be one highly invaginated and dissected vacuole extending throughout the cell. A highly developed grana fretwork within the plastids implies full photosynthetic capability and the capability of producing the osmoticulum required for turgor change. No plasmodesmata occur between the sister guard cells or between the guard and epidermal cells. It is postulated that there is a close relationship between plastid development and the presence or absence of plasmodesmata. No microbodies were positively identified in any of the guard cells. Microtubules appear to lie in two planes, thereby giving support to the “two system” observation for microtubules in the guard cells of Pisum sativum.     

THE FINE STRUCTURE OF THE GRASS GUARD CELL

Brown, W. V., and Sr. C. Johnson. (U. Texas, Austin.) The fine structure of the grass guard cell. Amer. Jour, Bot. 49 (2): 110–115. Illus. 1962.—An electron microscopic study of 16 species of grasses classified in 10 tribes and 5 subfamilies has revealed some hitherto unknown facts about guard-cell structure. In species of 3 subfamilies, but not in the Festucoideae, there are membranes on the guard cells overarching the stoma. In the Festucoideae, the membrane is rudimentary or absent and is associated with a different cross-sectional shape of the guard cell. The central canal through the thick-walled region of the guard cell is structurally quite complex. The wall between the central canal and the subsidiary cell is thin and lacks plasmodesmata. There are plastids but no developed chloroplasts in grass guard cells. Mitochondria are abundant, but vacuoles are undetectable. At the ends of the guard-cell pair, the wall between them is incomplete and the protoplasts are confluent.     

ULTRASTRUCTURE AND DEVELOPMENT OF THE INACTIVE STOMATA OF ANABASIS ARTICULATA (FORSK.) MOQ.

The guard cells of Anabasis articulata mature and senesce a short distance from the intercalary meristem in which they form. When the guard cells reach final size, their ultrastructure is similar to that of stomata of other plants. At this stage, they contain clearly definable, numerous mitochondrial profiles, chloroplasts with starch grains and plastoglobuli, active Golgi bodies, a large nucleus that stains deeply for chromatin and large vacuoles. During later stages of development the whole protoplasmic content becomes very dense, with myelin-like figures and crystals appearing in the vacuoles. The cell walls thicken considerably. This is especially true of the tangential walls, where the microfibrils of different lamellae vary in their orientation. It is suggested that as a result of these ultrastructural changes the guard cells lose the ability to move.     

狭基巢蕨叶表皮的结构和气孔器发育的观察

狭基巢蕨Ｎｅｏｔｏｐｔｅｒｉｓａｎｔｒｏｐｈｙｏｉｄｅｓ（Ｃｈｒｉｓｔ）Ｃｈｉｎｇ叶片的上表皮无气孔器,仅具表皮细胞,下表皮由表皮细胞和气孔器组成,气孔指数为２．５。上下表皮细胞和气孔器的细胞中均含有叶绿体。每个气孔器由２个肾形的保卫细胞和２～６个副卫细胞组成,其中以３个和４个副卫细胞的占绝大多数（３细胞的占４５．１％,４细胞的占４３．５％）。从发育上看,气孔器原始细胞进行２次分裂,产生２个保卫细胞和１个同源的副卫细胞。气孔器的发育过程大体可分为４个时期：（１）气孔器原始细胞的分化和分裂期;（２）保卫细胞母细胞成熟期;（３）保卫细胞母细胞分裂和气孔器幼期;（４）气孔器成熟期。狭基巢蕨的气孔器属于中周型     

Direct Measurements of Turgor Pressure Potentials of Guard Cells: II. THE MECHANICAL ADVANTAGE OF SUBSIDIARY CELLS, THE SPANNUNQSPHASE, AND THE OPTIMUM LEAF WATER DEFICIT

Evidence of the mechanical advantage of subsidiary cells wasobtained by simultaneous measurements of turgor pressure potentialsin adjacent subsidiary and guard cells using injection circuitswith two separate needles. In Tradescantia virginiana the mechanicaladvantage approaches two. Using the same technique evidencewas obtained that the Spannungsphase is, in the first place,a turgor relations phenomenon due to the mechanical advantageof epidermal or subsidiary cells. In addition, the evidenceindicated that the elastic properties of guard cell walls mayundergo changes during the Spannungsphase when potassium iontransport commences. During these measurements it was confirmedthat the optimum leaf water deficit for maximum stomatal openingoccurs when the epidermal turgor is near zero. Under these conditionsthe width of the stomatal pore is a function of the turgor pressureof the guard cells, since at zero turgor of the subsidiary cellstheir mechanical advantage has disappeared.     

STRUCTURE AND ONTOGENY OF THE STOMATAL COMPLEX IN PINUS STROBUS L. AND PINUS BANKSIANA LAMB.

The morphology of the stomatal complex in Pinus strobus L. and P. banksiana Lamb, is described and it is proposed that the stomatal complex should be considered an eight-celled complex consisting of two guard cells, and two polar, two lateral, and two hypodermal subsidiary cells. An ontogenetic study found these cells closely related developmentally. It was also found that the stomatal complex in these two pines could not readily be classified as haplocheilic because a polar subsidiary cell arises from the same protodermal cell as does the guard cell mother cell. A modification of the classical concept of stomatal development was necessary to describe the stomata as eumesoperigenous.     

蚕豆气孔运动中水通道和离子通道的作用和地位的探讨

 用不同浓度HgCl2、LaCl3和TEACl (Tetraethylammonium chloride)处理蚕豆(Vicia faba)叶片下表皮条,发现HgCl2能显著抑制气孔开闭,Ca2+通道阻塞剂LaCl3或K+通道阻塞剂TEACl处理也都有一定程度的抑制。三者的作用效果HgCl2>>LaCl3>TEACl。用HgCl2+LaCl3、HgCl2+TEACl或HgCl2+LaCl3+TEACl处理,则气孔开闭运动几乎完全被抑制。表明：蚕豆气孔运动中,保卫细胞胀缩主要是水通道直接参与保卫细胞与叶肉细胞间水流的调节引起的,离子通道起间接次要作用,二者共同引起保卫细胞体积变化而导致气孔开闭。     

THE ULTRASTRUCTURAL CYTOLOGY OF THE DIFFERENTIATING GUARD CELLS OF VIGNA SINENSIS

Structural differentiation of the guard cells of Vigna sinensis results from the integration of the following interrelated processes: a) intense activity of ribosomes, dictyosomes, endoplasmic reticulum (ER) membranes and mitochondria and patterned organization of microtubules; b) unequal thickening and ordered micellation of their walls and opening of the stomatal pore; and c) the divergent differentiation of the plastids. In differentiating guard cells, microtubules appear anticlinally oriented and more or less evenly distributed along the unthickened part of the dorsal wall and in the middle part of the ventral wall where thickening of the future pore occurs. In periclinal walls, microtubules fan away from the margins of the increasing thickening of the ventral wall and, later, from the rims of the stomatal pore towards the dorsal walls, parallel to the depositing radial microfibrils. Microtubules may be the cytoplasmic elements underlying guard-cell morphogenesis. Although cell-plate organization in guard-cell mother cells does not seem to differ from that of other protodermal cells, the middle lamella of the ventral wall becomes electron-translucent. The stomatal pore develops schizogenously from the internal and/or external ends of the ventral wall and proceeds inwards, remaining incomplete in most of the stomata of plants grown for 30 days in darkness and in some malformed ones which were developed after a prolonged action of colchicine. The guard cell, when approaching maturity, loses its organelle complexity and plasmodesmata, but it keeps a significant portion of its cytoplasm and organelles. Perigenous stomata generally exceed the size of mesoperigenous and mesogenous ones, develop large vacuoles and appear able to induce oriented divisions in their vicinity.     

ACTION OF FUSICOCCIN ON THE POTASSIUM BALANCE OF GUARD CELLS OF PHASEOLUS VULGARIS

Fusicoccin induces stomatal opening in both the light and dark. The stomatal aperture and K content of guard cells was measured to determine whether the action of fusicoccin in inducing stomatal opening is directly related to the uptake of K by the guard cells. Both detached and attached epidermis was treated with fusicoccin and the K content was determined by staining with cobalt sodium nitrite or by electron probe microanalysis. The K content of guard cells in detached epidermal strips floated on 10 μm fusicoccin in 10 mm KCl and aqueous CH₃OH (0.02%, v/v) increased in the light and dark as the stomata opened. After exposure to fusicoccin for 6 hr in the light, however, the stomata were closed and no K could be detected in the guard cells. The K content of guard cells of attached epidermis painted with fusicoccin also increased as the stomata opened, but the concentration of K in the subsidiary cells was not significantly altered by fusicoccin-stimulated opening. Moreover, painting with fusicoccin did not significantly change the Ca and P content of the guard or subsidiary cells. Stomata of epidermal strips, opened to their maximum width by fusicoccin, showed only a small and temporary closure when transferred to a solution of 10 μm abscisic acid. The use of metabolic inhibitors suggested that energy for the uptake of the K may be provided by both photophosphorylation and oxidative phosphorylation.     

GFP-mTn融合蛋白对蓝猪耳生活细胞微丝骨架的标记

用农杆菌介导法将嵌合基因GFP-mTn(mTn是微丝结合蛋白Talin的微丝结合域,可以显示活体细胞中微丝的结构)导入蓝猪耳.经激光共聚焦显微镜观察了转基因植株的各种不同组织中融合蛋白的表达和分布情况.在叶片的表皮细胞、保卫细胞、根部的皮层细胞中有融合蛋白的不同程度表达.但仅在保卫细胞中微丝标记状况良好,显示基因表达的组织特异性.经光诱导处于开放态的气孔的保卫细胞微丝呈网状结构,在细胞内无规则分布;经黑暗诱导处于关闭态的气孔保卫细胞中微丝束沿保卫细胞纵轴排列,呈卷曲状分布,并观察到螺旋和环状的微丝结构.在转基因植株的其他部位,例如茎表皮细胞、根毛细胞和花粉粒中,未检测到目的基因的表达.本研究获得的转基因植株为研究气孔运动过程中微丝动态变化提供了有用的材料.     

Studies in Stomatal Behaviour: VI. AN INVESTIGATION OF THE LIGHT RESPONSES OF WHEAT STOMATA WITH THE ATTEMPTED ELIMINATION OF CONTROL BY THE MESOPHYLL

An apparatus is described enabling light responses of wheatstomata to be followed by periodical porometer readings, betweenwhich the substomatal cavities can be swept with carbon dioxide-freeair forced in through the stomata. This is held to eliminatethe influence of changes in the carbon dioxide content of theintercellular space atmosphere brought about by photosynthesisand respiration in the mesophyll. Using this apparatus in anexperiment of ‘Latin square’ design with 6-foldreplication of three light treatments, a statistically significantresponse to light was found in a leaf area subjected to varyinglight intensities from 90 to 800 f.c. This response was reflectedin a similar significant effect, though of smaller magnitude,occurring in a similarly swept ‘control’ area 2cm. distant and maintained at a constant light intensity of270 f.c, the intervening portion of leaf being illuminated with800 f.c. throughout. It is argued that this transmission ofa light effect from one area to another does not occur via theintercellular spaces, nor by means of carbon dioxide gradientsfrom cell to cell. It is concluded from the data that thereis an indirect effect of light and perhaps also a direct effectupon the guard cells themselves; it is probable that neitherof the two effects concerned operates by reduction of the internalcarbon dioxide content in the guard cells.     

THE CUTICLE OF DREPANOPHYCUS SPINAEFORMIS,A LONG-RANGING DEVONIAN LYCOPOD FROM NEW YORK AND EASTERN CANADA

The presence of paracytic stomata and paired guard cells on specimens presumed to be Drepanophycus spinaeformis Göppert from eastern Canada and New York State supports the conclusion of Banks and Grierson that the species is not a reliable index of Lower Devonian strata. The interpretation of stomatal morphology demonstrates that the species lived in Early, Middle, and Late Devonian time and that slender specimens are distinct from zosterophylls such as Sawdonia that had anomocytic stomata and a single guard cell. Knowledge of the stomata also permits a reinterpretation of the stomatal apparatus as first described by Lang. Siegenian specimens of the genus apparently represent the oldest occurrence of paired guard cells and of paracytic stomata.     

伤胁迫对蚕豆叶片中茉莉酸分布的影响

在植物应对伤害等环境刺激的反应中,已知茉莉酸(JA)作为一种重要的信号分子在植物体内长距离运输,但目前对JA的细胞和亚细胞定位知之甚少。本研究用免疫荧光显微镜技术和免疫胶体金电镜技术证明茉莉酸分布在蚕豆叶片叶肉细胞的叶绿体、表皮细胞的细胞壁、保卫细胞的细胞壁、细胞质、叶绿体和细胞核上。其中保卫细胞的叶绿体和细胞核是JA分布的主要场所。叶片的局部灼伤可提高JA在质外体和气孔保卫细胞中的水平。由此推测,伤胁迫下JA分配的改变可能与植物体防御反应密切相关,并参与了对气孔运动的调控。     

THE SUSCEPTIBILITY OF THE PLANT CELL TO VIRUS DISEASE

A number of spraying experiments showed that the virus cannot enter a plant unless some of the cells are injured. It is not essential that such injury should be brought about in the presence of the virus. The chances of infection fall off rapidly in the first few minutes after injury, but infection occurs occasionally as long as half an hour after the cell is damaged.
Inoculations by micropipette into single cells of the host plant yielded only about one-tenth of the expected number of infections. This suggests differences in the susceptibility of the cells to virus attack.     

THE FINE STRUCTURE OF GENETIC TUMOR CELLS

Tissue from genetic tumors at an early stage of development on young seedlings of Nicotiana suaveolens x N. langsdorffii was examined with the electron microscope. Such tumors, which first appear on the stem immediately below the petioles of the first and second leaves, are composed essentially of three cell types. They are covered by a single layer of epidermal cells of which two specializations, guard cells and trichomes, were observed. The majority of cells in the tumors are large, irregularly shaped, highly vacuolated, parenchymal cells. Meristematic cells, which are found in clusters close to the surface of the tumor, are the third cell type. A membrane-bound inclusion was observed within the plastids of all of the cell types within the tumor. It consists of granular material which accumulates within an intrathylakoid space. There are no major differences in ultrastructure between parenchymal cells of genetic tumors and their normal counterparts from stems without any signs of tumor formation.     

Current concepts on the role of potassium in stomatal movements

A stoma opens when the surrounding guard cell pair increases in turgidity. The increase results from active accumulation of potassium in the guard cell vacuole. The intracellular compartmentation of potassium evokes compensatory accumulation of a yet-unidentified solute in the guard cell cytoplasm. The source of potassium is other epidermal cells; this indicates that stomatal movements in situ are under control of these cells also. Presumably, guard cell potassium uptake, which is from the apoplast, is mediated by a proton -extruding ATPase on the guard cell plasmalemma. The energy source is. oxidative phosphorylation and, to a lesser extent, photosynthetic electron transport. Except for high flux capacity and different responses to applied chemicals, potassium uptake by guard cells is similar to potassium uptake by other plant cells.     

COMPARATIVE ANATOMY OF THREE SPECIES OF THE APOPHYLLOUS GENUS GYMNOPHYTON

The anatomy of three species of Gymnophyton has been studied by light and electron microscopy. The species are essentially leafless and morphologically they are very much alike, but they differ anatomically and can be characterized just by their anatomical differences. SEM revealed great differences in stomatal structure, orientation, and dimensions. Micro-channels (ectodesmata) in the guard cell walls were disclosed in great numbers in G. isatidicarpum by using interference contrast microscopy, and these structures are thought to function as pathways for wax precursors. In older stems of this species the epidermis and cortical palisade tissue are isolated by a continuous periderm layer. Before dying, the palisade cells undergo alterations, and the stomata are permanently closed by cuticular plugs between the guard cells or by fusion of the swollen adaxial parts of the subsidiary cells. Similar permanent closure mechanisms are not found in G. polycephalum and G. robustum, which also deviate by having their stomatal openings orientated at a right angle to the axis of the stem and by the occurrence of collenchyma strands instead of fiber strands along the stem corner ribs. Gymnophyton polycephalum and G. robustum seem to be more closely related to each other than either is to G. isatidicarpum, but they differ markedly from one another in the size and structure of their stomatal complexes.     

中国春黄菊族植物叶表皮结构的研究

本文对分布在中国的春黄菊族(Anthemideae)中的25属98种植物叶的表皮结构进行了观察。1.毛状体的类型适于作为本族自然群、属、亚属、组或系的分类特征。2.轴型、半平列型和螺旋型等复合结构的气孔适于作属以下各单位的分类依据。3.表皮细胞的大小、气孔的保卫细胞长度和 T 型-毛的顶端长度等,这些只是数量特征,在本族分类上意义不大。