THE ANATOMIC RESPONSES OF DAUCUS CAROTA TO THE ASTER YELLOWS VIRUS

Struckmeyer, B. Esther. (U. Wisconsin, Madison.) The anatomic responses of Daucus carota to the aster yellows virus. Amer. Jour. Bot. 50(9): 959–963. Ilus. 1963.—The leaves, petioles, and roots of carrots (Daucus carota) displaying aster yellows virus in the field and those infected with the aster yellows virus inoculated by the 6-spotted leafhopper were examined anatomically. Compared to the uninoculated, the young infected leaves displayed fewer layers of palisade cells and larger spongy parenchyma cells with a more compact arrangement. Mature leaves of infected plants sometimes were undulated and had few chloroplasts, many of which appeared fragmented. Hypertrophy and hyperplasia in the phloem tissue were associated with some necrosis and obliteration of cells. Long, needle-shaped crystalline inclusion bodies were present in the phloem in the leaves and roots. Most of the vascular bundles of the petiole were abnormal. Malformations included proliferating phloem cells, which in some instances almost encircled the bundle, hyperplasia of the phloem, hypertrophy of the parenchyma, and considerable necrosis and obliteration of these cells. Other responses included the division into 3 or 4 rows of the large outer phloem parenchyma by parallel walls so that a cambium-like layer was simulated. The tissue enclosed by this layer divided and underwent considerable necrosis and gummosis. Lacunae were found between the phloem bundle cap and the older phloem. Some of the cells in the phloem tissue differentiated into bundles with xylem. Numerous, short, lateral roots were conspicuous on the main root. The most noticeable response of the root tissue to this malady was hyperplasia and hypertrophy of the phloem followed by cellular disorganization, necrosis, and obliteration of cells. Some sieve tubes, companion cells, and parenchyma contained a gumlike deposit.     

几种萝卜提取物在组织培养细胞中的抗病毒感染活性

我们曾报道,白萝卜提取物是一种干扰素诱生剂,对致死性病毒感染动物有很显著的保护作用。 本实验在组织培养单层细胞上测试了十字花科萝卜属几种萝卜栽培变种,包括“心里美”、“卫青”、“象牙白”(白萝卜)和伞形科胡萝卜提取物的抗病毒感染活性。 萝卜提取物的制备和定量方法,按文献进行。萝卜提取物在组织培养单层细胞上抑     

THE ROLE OF ZINC IN THE GROWTH OF PLANT TISSUE CULTURES

Klein , Richard M., Emerita M. Caputo , and Barbara A. Witterholt . (New York Bot. Gard., N. Y., N. Y.) The role of zinc in the growth of plant tissue cultures. Amer, Jour. Bot. 49(4): 323–327. Illus. 1962.—Zinc-sufficient and zinc-deficient auxin-auxotrophic callus and auxin-prototrophic crown-gall cultures of Parthenocissus tricuspidatus were examined for their growth capacity and ability to synthesize tryptophan. Growth capacity decreased rapidly when zinc ion was withheld and tryptophan synthetase activity in vitro was reduced. Growth of –Zn crown-gall tissues was stimulated by either auxin or tryptophan and growth of –Zn callus cultures was stimulated by tryptophan.     

SEED MORTALITY IN DAUCUS CAROTA POPULATIONS: LATITUDINAL EFFECTS

Daucus carota, a common herbaceous weed, grows over a wide latitudinal range in eastern North America. Viability and germination tests of mature seeds collected from 36° to 45°N were conducted to measure predispersal seed mortality. Viability and germination declined as latitude of the seed source decreased. Only 30–50% of the seeds from southern populations germinated owing to high embryo inviability and absence of embryos. Sixty to ninety percent of the seeds from northern populations germinated. Reciprocal planting of seeds in outdoor experimental plots at three latitudes and testing of seeds over two generations together showed that the environment in which seeds mature, rather than environmental preconditioning over generations or genetically-based differences among populations, explain this variation in germination ability. Within-latitude germination declined in experimental plots as population age of the seed source within latitudes increased. The data indicate that predispersal seed mortality can influence local population persistence and that seed mortality is an increasingly important factor in population regulation at the southern limit of the species’ range.     

CALCIUM AND THE CONTROL OF LIGNIFICATION IN TISSUE CULTURES

Lipetz , Jacques . (Rockefeller Inst., New York, N. Y.) Calcium and the control of lignification in tissue cultures. Amer. Jour. Bot. 49(5): 460–464. Illus. 1962.—Crown-gall tissues of Helianthus, Parthenocissus, Nicotiana, habituated Nicotiana, normal carrot, and Parthenocissus tissues grown in vitro on media low in calcium show an increase in lignification. The lignin is deposited not only on the walls of tracheids but on the walls of parenchymatous cells as well. Transferring the tissues to media containing higher calcium concentrations inhibits this excess lignification. Neither strontium nor magnesium could be substituted for calcium. These studies indicate that the availability and concentration of inorganic ions play a role in the control of lignification.     

ADVENTIVE ORGANOGENESIS FROM SOMATIC TISSUE CULTURES OF SOLANUM CAROLINENSE: ORIGIN AND DEVELOPMENT OF REGENERATED PLANTS

The development of adventitious shoot formation from cultured somatic tissues of Solanum carolinense was studied using light microscopy. For purposes of comparison, callus initiation and proliferation were also followed. When stem segments of this plant were cultured on medium supplemented with 6 mg/l benzyladenine (BA), cell division was first observed after 48 hr in the external phloem and inner cortex of the segments. This division activity gave rise to meristematic zones which subsequently formed shoot primordia within 6 days of culture. While organogenic potential appears to be limited to specific regions, all tissues of the explant were capable of callus formation when cultured on medium containing 3 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D). In conjunction with a previous study, it appears that unlike somatic embryogenesis in this species, organogenesis does not require an intermediate callus phase for differentiation to occur.     

PIGMENTS AND PLASTIDS IN CULTURES OF TOTIPOTENT CARROT CELLS

Cells from a strain of carrot which was prone to form deep-seated chlorophyll in its storage organ have been cultured in a manner that promoted them to organize into plantlets. Whereas the free cells contained only chloroplasts, the plantlets derived from these cells formed all types of plastids (“proplastids,” leucoplasts, chromoplasts, and chloroplasts) in accordance with the location of the cells in question in the developing plant body. The developmental history of the plastids has been traced with the electron microscope. The events of chloroplast development, previously described by Israel and Steward (1967) for cultured carrot explants, have been verified. The bearing of this new evidence upon the control of plastid development and biochemistry is discussed and related to other recent studies. The conclusion is that all totipotent carrot cells have plastids as essential organelles but that their final form and content are sharply defined by the factors inherent in the location of the cells in the plant body as it emerges.     

He—Ne激光对君子兰幼果和胡萝卜根的愈伤组织形成及生长的影响

利用6mv的He—Ne激光器,每天对君子兰幼果、胡萝卜根的外植体辐照5分钟,连续辐照20天,对愈伤组织的形成和生长有一定的促进作用。但同样条件下,辐照10分钟,对君子兰幼果,胡萝卜根的愈伤组织形成和生长都有明显的抑制作用。     

结球甘兰下胚轴组织培养形态发生的组织学研究

结球甘兰离体下胚轴培养,近切口的中柱薄壁细胞首先启动分生,中柱外的内皮层,皮层,表皮细胞随后也启动分生。随着愈伤组织的生长和愈伤形成层的建成,维管组织与分生组织产生。组织培养中出现的多倍性细胞团和单倍性细胞,不会引起原二倍体物种的遗传性变异和性状变化。在愈伤组织中,芽多为外起源。由原体原始细胞和原套原始细胞发育成芽原基,进一步形成不定芽。另外,不定芽还可由外植体皮层内薄壁组织直接产生。不定根为内起     

PHASE CONTRAST OBSERVATIONS OF THE ENDOPLASMIC RETICULUM IN LIVING TISSUE CULTURES

Cells from three human sources (two malignant and one fetal) were observed through phase contrast microscopy to contain unusual cytoplasmic images. These were photographed and are discussed as representing the endoplasmic reticulum in the living cell.