STUDIES ON THE FLORAL HISTOGENESIS AND PHYSIOLOGY OF PERILLA. III. EFFECTS OF INDOLEACETIC ACID ON THE FLOWERING OF APICAL BUDS AND EXPLANTS IN CULTURE

Raghavan , V. (Princeton U., Princeton, N. J.) Studies on the floral histogenesis and physiology of Perilla. III. Effects of indoleacetic acid on the flowering of apical buds and explants in culture. Amer. Jour. Bot. 48(10): 870–876. Illus. 1961.—The responses of apical buds and explants of a short-day plant, Perilla frutescens (L.) Britt. var. 'Tall Late,' when grown in vitro in White's medium supplemented with indoleacetic acid (IAA) and subjected to short-days (SD) or long-days (LD), are described. Additions of varying concentrations of IAA to the medium inhibited the flowering of the photoinduced apical buds in 2 ways. There was a progressive delay in the appearance of the first signs at the apex and a gradual transition from the more flower-like structures in lower concentrations of IAA (0.1 mg/liter) to sterile cones in higher doses. The sterile cones had florets with well-developed calyx and corolla lobes, but lacked the sporogenous tissues. When subjected to LD, visible signs were observed only in buds grown in 0.1 and 1.0 mg/liter IAA, the pronounced effect of the auxin being in the step-wise inhibition in the formation of the non-sporogenous tissues of the differentiating florets. Flowering of the explants with the 1st pair of unfolded leaves was also inhibited by IAA in either SD or LD, but the 1st signs appeared relatively faster than in apical buds. When photoinduced, explants with the 1st and 2nd pairs of unfolded leaves flowered in all concentrations of IAA tried (up to 100 mg/liter) while those kept in LD remained entirely vegetative.     

紫苏腺毛的形态结构和发育的研究

紫苏（Perillafrutescens（L．）Britton）叶上腺毛的研究表明：叶上腺毛主要有两种类型,一是头状腺毛,二是后状腺毛。两类腺毛都是由1个基细胞、1个柄细胞和由分泌细胞组成的头部构成。头状腺毛的头部由1个、2个或4个分泌细胞构成,其头部呈圆球形或半圆球形。盾状腺毛的头部也由1个、2个、4个或8个分泌细胞构成,其分泌细胞横向扩展使头部呈盾状。分泌盛期,大量分泌物充满角质层下间隙。两类腺毛的原始细胞均起源于叶原基或幼叶的原表皮层细胞,它通过两次平周分裂形成1个基细胞、1个柄细胞和1个头细胞,头细胞不分裂或依次进行1—3次垂周分裂,分别形成单细胞、2细胞、4细胞或8细胞的头部。     

石斛离体培养中ABA对诱导花芽形成的影响

由兰科植物铁皮石斛（Ｄｅｎｄｒｏｂｉｕｍ ｃａｎｄｉｄｕｍ Ｗａｌｌ．ｅｘ Ｌｉｎｄｌ．）种子诱导形成的愈伤组织,在光照下置于ＭＳ附加０．３ ｍ ｇ／ＬＮＡＡ 的培养基上繁殖,可以形成原球茎。将原球茎转入ＭＳ含２ ｍ ｇ／Ｌ ６－ＢＡ 和０．５ ｍ ｇ／ＬＮＡＡ 的培养基上,花芽形成频率为２７．０％ 。原球茎先在０．５ ｍ ｇ／ＬＡＢＡ的培养基上预培养１５ ｄ,再转入含２ ｍ ｇ／Ｌ６－ＢＡ 的ＭＳ培养基上培养,花芽形成频率明显提高,可达８４．４％ ,而且每株植株花的数目增加;但是在仅有ＡＢＡ 的ＭＳ培养基上培养的原球茎再生的植株未见花芽形成     

紫苏与白苏不同化学型挥发油成分的研究

本文对不同地区的八个紫苏、白苏样品进行了植物形态与挥发油化学成分的对比研究。花为白色、植物全绿者其挥发油主要成分为紫苏酮,此植物为紫苏酮型。花为淡紫色,植株全紫者(老叶叶面为绿色,叶背面为紫色)其挥发油的主要成分为紫苏醛,此植物为紫苏醛型。花为粉白色,叶子面绿背紫绿色或者叶绿,叶柄、茎为紫绿色者其挥发油主要成分为莳萝油脑或肉豆蔻醚,此植物为苯丙烯基型。     

紫苏愈伤组织迷迭香酸的纯化及抗菌活性研究

紫苏叶外植体在添加ＮＡＡ和２,４－Ｄ的ＭＳ培养基上诱导分化愈伤组织,愈伤组织中迷迭香酸的含量为８５％,愈伤组织干燥后经乙醇提取,乙酸乙酯萃取后,经Ｓｅｐｈａｄｅｘ ＬＨ－２０柱层析,最后获得了纯度为９５％的迷迭香酸。抑菌实验表明此法获得的迷迭香酸对大肠杆菌、金黄色葡萄球菌及立枯丝合菌的生长均有明显的抑制作用,其最低抑制浓度分别为３００、４００及８００μｇ／ｍＬ。     

HISTOCHEMICAL AND AUTORADIOGRAPHIC STUDIES OF FLORAL INDUCTION IN CHENOPODIUM ALBUM

Gifford , Ernest M., Jr. , and Herbert B. Tepper . (U. California, Davis.) Histochemical and autoradiographic studies of floral induction in Chenopodium album. Amer. Jour. Bot. 49(7): 706–714. Illus. 1962.—Chenopodium album was induced to flower using short-day photoperiods. Changes in the chondriome, starch, total protein, ribonucleic acid (RNA), deoxyribonucleic acid (DNA), and histone distribution in cells of vegetative and inflorescence shoot apices were studied. The distal cells of the vegetative apex (especially the axial tunica cells) possess larger nucleoli and vacuoles, less granular mitochondria, and more differentiated plastids than do other cells of the apex; the distal cells stain lightly with dyes that indicate the presence of DNA and histone. RNA is distributed relatively uniformly in the shoot apex; the cells at sites of leaf initiation and young leaf primordia contain slightly higher concentrations of RNA than the axial cells of the shoot apex. Protein is uniformly distributed throughout the vegetative as well as the inflorescence apex. Upon induction, the chemical and morphological differences between cells in the shoot apex gradually disappear. RNA concentration of cells in the apex increases, reaching a maximum after 4 inductive cycles. Protein concentration of cells also increases, but this increase lags behind that of RNA.     

STEREOLOGICAL STUDY OF ULTRASTRUCTURAL CHANGES IN THE SHOOT APICAL MERISTEM OF NICOTIANA TABACUM DURING FLORAL INDUCTION

Shoot apices of a short-day sensitive line of Nicotiana tabacum L. cv. NCTG-22 have been examined by electron microscopy for ultrastructural changes which occurred in the central zone over a 17-day period during the transition from vegetative to reproductive growth. Plants were grown in controlled-environment chambers of the NCSU Phytotron and exposed to an inductive photoperiod after a 6-wk juvenile phase. Ultrastructural changes were investigated from photomicrographs using a semi-automatic stereological procedure and a microcomputer. After exposure to only one inductive cycle cell and nuclear cross sectional areas in short-day plants were significantly larger than in long-day controls. Subsequently, under short days cross sectional areas of cells, nuclei, vacuoles and proplastids decreased, while mitochondrial cross sectional area and relative volume increased during the course of the induction period. In induced apices as cross sectional areas and relative volumes of vacuoles and proplastids decreased, their profile numbers increased. The reduction in cross sectional areas of cells and most organelles was associated with an increase in rate of leaf initiation and size of the apical dome. The demand for sufficient energy input to maintain the surge in growth and activity preceding floral initiation was reflected by the significant increases in cross sectional area, profile numbers and density of the mitochondria population. Even though the transition period is quite long for Nicotiana, cells and organelles in the central zone were observed to progress through similar changes in morphology that are known to occur in Sinapis and Xanthium which exhibit a more rapid and absolute response to photo-induction.     

THE ROLE OF LIGHT IN HISTOGENESIS AND DIFFERENTIATION IN THE SHOOT OF PISUM SATIVUM. I. THE APICAL REGION

Thomson , B. F., and P. M. Miller . (Connecticut Coll., New London.) The role of light in histogenesis and differentiation in the shoot of Pisum sativum. I. The apical region. Amer. Jour. Bot. 49(3): 303–310. Illus. 1962.—Seedlings of Pisum sativum grown under constant conditions and kept in total darkness or exposed daily to red or white light were harvested at the same plastochron age and examined histologically to determine what specific aspects of histogenesis and differentiation are affected by light. The tissue organization of the shoot apex is the same in all light conditions to a point below the 2 youngest leaf primordia. The first detectable difference is a slight thickening of the internode in light due to more and larger cells. The first effect on longitudinal growth appears below the fourth youngest primordium and consists of an increase of internode length in light-grown plants. This is associated with a greater distance between the apex and the first mature protoxylem. The distance from apex to the first pith, provascular strands, and protophloem and the distances between the 4 youngest leaf primordia are not affected by light.     

紫苏腺毛的形态发生研究

紫苏叶上有两种腺毛：质状腺毛和头状腺毛。两者都具１个基细胞、１个柄细胞和头部。前者的头部可由１、２、４或８个分泌细胞组成,扩展成质状;后者的头部由１、２或４个分泌细胞组成,聚成圆球状。两种腺毛的原始细胞都来源于原表皮细胞,经两次平周分裂产生基细胞、柄细胞和顶细胞。在腺毛后期的形态发生中,柄细胞的分化状态决定腺毛的类型。若柄细胞保持扁平关且处于分生状态时,其顶细胞将发育成质状腺毛的头部;若柄细胞纵向     

紫苏、白苏的抑菌实验

用不同溶剂浸泡或处理紫苏后,进行抑菌实验,结果表明：１０％以上浓度的紫苏水浸液,１２．５％水煎液和乙醇提取液对白色念球菌、新型隐球菌以及红色毛癣菌、石膏样小孢子癣菌、絮状表皮癣菌有较好的抑菌效果。紫苏、皱紫共、白苏对真菌均有抑菌作用,但皱紫苏对绿脓杆菌、白苏对克柔氏念球菌、白色念球菌以及绿脓杆菌效果更为明显。     

离体植物花芽和花器官的发育研究进展

在近二十几年,尤其是近十年由于离体培养技术的完善和进一步向精确的层次的发展,已使得许多种植物花序、花芽和单独花器官以及部分的花器官在体外成功地进行了培养和尝试,并且对花芽及花器官的离体发育有了更深入的认识。不同植物的花发育需要不同的植物生长调节剂以及它们的不同配比,并且不同植物在其花发育所需要的营养因子也存在着相当大的差异性。这种差异性又随植物器官及花发育的不同阶段而受到加大或缩小。通过对正常花及突变体花进行的离体培养实验研究已经对一些花器官发生过程中的调节程序有了新的了解。利用离体培养技术,包括刚发展起来的薄层细胞培养技术在阐明花发育的机理、形态建成的分子机制以及成花梯度的物质基础等问题上具有广阔的潜力。     

THE EARLY ACTION OF THE FLORAL STIMULUS ON MITOTIC ACTIVITY AND DNA SYNTHESIS IN THE APICAL MERISTEM OF XANTHIUM STRUMARIUM

Vegetative plants of Xanthium strumarium (a short-day species) were induced to flower by exposure to a single 16-hr long night. By cutting off the induced leaf (half-expanded leaf) at various times, it was established that, by 8 hr after the end of the long night, a sufficient amount of floral stimulus had reached the meristem to induce a flowering response. The following sequence of events occurred in both the peripheral and central zones of the apical meristem of induced plants: 1) a rise in the mitotic index beginning at 28 hr after the end of the long night and culminating at 36 and 56 hr; 2) a stimulation of DNA synthesis starting at 32–36 hr and reaching a maximum at 60 hr; 3) an increase in nucleolus diameter starting at 32 hr. The cell population in the meristems of both vegetative and induced plants displayed a similar distribution, with about 80 % of the nuclei with the 2C amount of DNA. The comparison of the kinetic data concerning the mitotic index and DNA synthesis indicated that one of the early effects of the floral stimulus in the peripheral and central zones was the release in mitosis of cells whose nuclei were in the postsynthetic (G₂) phase of the mitotic cycle. In the pith-rib meristem, the following events were recorded: 1) a stimulation of DNA synthesis starting at 20 hr; 2) a rise of the mitotic index beginning at 28 hr; 3) the vacuolation and elongation of cells starting at 48 hr. All these events occurred well before the initiation of bract and flower primordia, which began at 96 and 136 hr, respectively. Neither stimulation of mitotic activity nor flowering occurred in the meristems of plants subjected to a long night interrupted at its midpoint by a 5-min light break. The results are discussed in relation to the early events which are known to occur in the meristems of other photoperiodic species in transition to flowering.     

STUDIES IN THE PHYSIOLOGY OF FUSARIA. THE RESPIRATORY AND FERMENTATIVE MECHANISMS

1.Fusarium tricothecoides was selected for a study of the respiratory and fermentative activities of Fusaria. "Resting cell" suspensions were investigated by the Barcroft manometric technique. 2. The results of the investigation indicate clearly that the mechanism of endogenous metabolism (respiration) is distinct from the exogenous mechanism (fermentation). Anaerobically no significant CO₂ production is apparent without added substrate. In the presence of glucose the anaerobic CO₂ evolution is practically equal to the added CO₂ evolved aerobically in the presence of added glucose. Low concentrations of iodoacetate or fluoride selectively poison the exogenous mechanism but do not affect the endogenous mechanism. Alcohol is not produced in the course of endogenous metabolism, but is produced in the presence of added glucose. 3. A study of the metabolism of the organism throughout its entire growth phase from 1 to 7 days has been made. 4. The ability of suspensions of Fusarium sp. H., obtained by growth on a variety of common substrates, to attack a large number of carbon sources with the production of exogenous CO₂ was determined. It is found that organisms grown on glucose will attack only glucose, mannose, and fructose, but none of the common intermediary metabolites except pyruvic acid. Organisms grown on galactose attack galactose, as well as the other hexoses, indicating an adaptive mechanism. 5. An identical mechanism for the dissimilation of glucose, mannose, and galactose is indicated since no additive effects with these substrates were observed. Growths on non-hexose carbon sources attack glucose slightly under the experimental conditions with the evolution of CO₂, but do not attack any other substrate. This would indicate a residual glucose-dissimilating mechanism in all growths investigated. 6. Striking similarities between the general metabolism of resting suspensions of Fusarium sp. H. and resting suspensions of yeast cells are apparent.