Liquid Endosperm Research Articles

Trisetum curvisetum (Poaceae: Aveneae), a New Species from Mexico

Trisetum curvisetum is a new species from high Sierra Madre Oriental in Nuevo Leon, Mexico. Its soft rather than liquid endosperm is new for the genus, and its lemma awn is thin and flexuous, easily distinguishable from that of other North AmericanTrisetum.

Translocation and Metabolism of Endosperm-Applied [2-14C] Indoleacetic Acid in Etiolated Avena sativa L. Seedlings

The role of free indole-3-acetic acid (IAA) in the endosperm of Avena sativa L. seedlings was investigated to determine its contribution to free IAA in the shoot. [2-(14)C]IAA was injected into the endosperm of darkgrown seedlings and the transport and metabolism of the [(14)C]-labeled compounds determined. It was concluded that translocation of free IAA directly from the endosperm is probably not a significant source of free IAA in the shoot, mainly because even small amounts of [(14)C]IAA introduced into the endosperm were rapidly metabolized. This suggested that, in Avena, free IAA does not normally exist in the liquid endosperm.

Comparative Effects of Ancymidol and Its Analogs on Growth of Peas and Ent-Kaurene Oxidation in Cell-Free Extracts of Immature Marah macrocarpus Endosperm

The plant growth retardant alpha-cyclopropyl-alpha-(4-methyoxyphenyl)-5-pyrimidine methyl alcohol (ancymidol) and a series of analogs of this substance in which one or more of the substituents were varied were tested for their comparative biological activity. The compounds were tested as inhibitors of internode elongation in peas and as inhibitors of the oxidation of ent-kaurene catalyzed by microsomal preparations from the liquid endosperm of Marah macrocarpus seeds. The relative effectiveness of a substance was generally the same as an inhibitor of the two processes. Ancymidol was the most effective. Substitution of the alcohol group of ancymidol by either methoxy or hydrogen groups reduced the activity only slightly. Substitution of the cyclopropyl group by an isopropyl moiety also had little effect on the activity. However, substitution of the cyclopropyl group with a phenyl or other aryl substituent greatly reduced the effectiveness of the analog as an inhibitor. Replacement of the 4-methoxyphenyl substituent with a similar substituent such as 4-chlorophenyl had little effect on activity, but replacement with a 2-methoxyphenyl group greatly reduced activity. Analogs in which the pyrimidyl moiety of ancymidol was modified were inactive in whole plants, but moderately active in the cell-free ent-kaurene oxidation system. The application of gibberellic acid can overcome the growth inhibitions due to treatment of the test plants with 10(-5)m or lower concentrations of the inhibitors. However, the inhibitory effects of 10(-4)m or higher concentrations of inhibitors on test plants were not overcome by the applications of exogenous gibberellic acid. These results support the idea that the effects of low concentrations of these substances on plant growth are primarily a consequence of their ability to inhibit ent-kaurene oxidation and gibberellin biosynthesis. Other modes of inhibition may operate at higher inhibitor concentrations.

Gibberellin-like Substances in Developing Fruits of Pecan1

Abstract Several gibberellin-like substances were detected by cucumber, dwarf pea, and lettuce bioassays after liquid chromatographic (HPLC) fractionation of liquid endosperm from the developing seed of pecan [Carya illinoensis (Wang.) K. Koch cv. Moneymaker]. The response of bioassays to authentic gibberellin standards and fractions eluted from the HPLC column at the same times as gibberellin A3, A4, and A7 suggests that these 3 gibberellins may be present in the liquid endosperm.

STARCH GRANULE FORMATION IN DEVELOPING SEEDS OF PISUM SATIVUM L.: EFFECT OF GENOTYPE

Cell development and starch granule formation in seeds of three pea (Pisum sativum L.) genotypes, R/R Rb/Rb, r/r Rb/Rb, and R/R rb/rb, affecting cotyledon starch were compared. Cotyledon cells at 10 days after flowering were highly vacuolated and contained small protein bodies in the vacuoles and small oval starch granules in the cytoplasm in all three genotypes. Gradients of cell development from the center to the periphery of the cotyledon and toward the cotyledon‐hypocotyl axis persisted through the cell enlargement, reserve synthesis, and into the maturation stages of cotyledon development. By 14 days after flowering, many small vacuoles lined with protein deposits had been formed. Vacuoles were only observed in peripheral and basal cells by 18 days after flowering. Starch granules were oval and birefringent in all three genotypes at 10 days. Starch granules in R/R Rb/Rb and R/R rb/rb cotyledons expanded regularly remaining nearly oval and birefringent throughout development. In contrast, starch granules from r/r Rb/Rb cotyledons began to fragment by 14 days after flowering. This process began as a single fissure, followed by a second fissure usually at or near right angles. Finally, because of the fragmentation, the granules appeared compound, and only a portion of the granule was birefringent. All genotypes contained nearly equal volumes of liquid endosperm and embryo at 10 days after flowering. In addition, a layer of parenchyma tissue (ovular and/or endospermic) inside the seed coat was observed. Although, thin walled and poorly defined cytologically, the parenchyma cells contained large numbers of starch granules. These granules were a mixture of simple and compound types in all genotypes. By 18 days after flowering, the parenchyma tissue was reduced to a small layer of cell walls and all starch granules had been mobilized.

Enzymatic Preparation of 14C-Labeled Phytoene, Squalene, and Geranylgeranyl Pyrophosphate from [2-14C]Mevalonic Acid

Methods are described for an enzymatic preparation of 14C-labeled terpenoids. With a cell-free system of a white mutant of Phycomyces blakesleeanus (Mucoraceae) [14C]squalene and [14C- cis]phytoene can be synthesized from [2-14C]mevalonate. The application of norflurazon, a phenyl- pyridazinone herbicide, helps to increase the yield of squalene. Furthermore, the liquid endosperm of Echinocystis lobata (Cucurbitaceae) was used for the formation of either [14C(-)]kaurene from [14C]mevalonic acid or [14C-/ra/w]geranylgeranyl pyrophosphate in the presence of Amo 1618. The hydrocarbons formed were purified by alumina-column chromatography and preparative thin-layer chromatography (TLC). Geranylgeranyl pyrophosphate was separated by DE-column chromatography followed by TLC.

Pecan, Pecan Weevil Management, 1979

Abstract Test blocks were established in a mature bearing native pecan grove at Hidden Valley Farms near Hamilton, TX in Hamilton Co. in Jul. Each block consisted of at least 10 trees covering a minimum of 2 acres. Pretreatment monitoring of pecan nut development and pecan weevil emergence from the soil were used to initiate the first application on Aug 23 when adult pecan weevil emergence was underway and the liquid endosperm of the nut kernel was observed to thicken. A 2nd treatment was made on Sept 3 and a 3rd on Sept 12. Evaluations were mode on Oct 18 by examining 300 nuts with shucks.intact from each treatment from a minimum of 4 trees within each treatment for immature stages of pecan weevil in the kernels and hickory shuckworm damage in the shucks. All chemicals were applied with a 500 gallon capacity speed sprayer as a dilute solution sprayed on the foliage to the point of runoff. No phytotoxicity to foliage or nuts was observed from any treatment. Carbaryl was the treatment standard.

The Localization in Cultured Carrot Cells of Factors that Induce their Growth

Various previously recognized parts of the complex of growth factors present in the liquid endosperm of the coconut or in immature fruits of Aesculus woerlitzensis were generally tritiated. The labeled growth factors were applied singly to culture media which contained balanced requirements that had caused carrot explants to proliferate and grow in accordance with combinations of growth factors supplied. By the usc of electron microscopy and autoradiography, the radioactivity from each source was detected in the cells and its density and distribution, in the form of developed grains over different cellular compartments and organelles, was determined. The tabulated data relate to four labeled sources as observed over seven cellular compartments under six experimental treatments. Electron micrographs also show how the radioactivity from the various sources related to organization of the cells. The distribution of radioactivity within the cells varied with the source. Both 3H-myo-inositol and the tritiated growth factors from Aesculus (3H-AF1Aesc) with which it interacts (as in so-called Growth Promoting System I) contributed radioactivity, preferentially, to cell walls and sites of their formation in culturcd carrot cells. Both 3H-IAA and 3H-zatin (as in so-called Growth Promoting System II) contributed their radioactivity preferentially to the nucleoli of the cultured cells. Some other conspicuous distributions of radioactivity (e.g. from 3H-AF1Aesc to plastids and from 3H-IAA to the interstitial substance, i.e. middle lamella, where enlarging cells separate) involved these tritiated moieties without regard to their counterparts in Growth Promoting Systems I and II, respectively. The problems raised by such multiple effects due to different growth factors acting singly and in combinations at different cell sites are both recognized and discussed.

Studies on the Specificity and Site of Action of α-Cyclopropyl-α-[p-methoxyphenyl]-5-pyrimidine Methyl Alcohol (Ancymidol), a Plant Growth Regulator

alpha-Cyclopropyl-alpha-[p-methoxyphenyl]-5-pyrimidine methyl alcohol (ancymidol) is an inhibitor of ent-kaur-16-ene oxidation in microsomal preparations from the liquid endosperm of immature Marah macrocarpus seeds. The K(i) for this inhibitor is about 2 x 10(-9)m. Ancymidol also blocks ent-kaur-16-en-19-ol and ent-kaur-16-en-19-al oxidation by the same preparations with a similar efficiency, but does not significantly inhibit ent-kaur-16-en-19-oic acid oxidation. Ancymidol appears to be specific for this series of oxidations in higher plant tissues. It does not inhibit the oxidation of kaurene nor kaurenoic acid in rat liver microsomes and has no significant effect on the oxidation of cinnamic acid in microsomal preparations from Sorghum bicolor seedlings. Ancymidol also does not inhibit kaurene oxidation in vitro nor in vivo in cultures of the fungus Fusarium moniliforme. The presence of ancymidol did not significantly alter the activities of NADPH-cytochrome c reductase, NADH-cytochrome c reductase, or NADH-cytochrome b(5) reductase. The addition of ancymidol to suspensions of oxidized M. macrocarpus endosperm led to a difference spectrum with an absorption maximum at 427 nm and a minimum at 410 nm.

Embryogeny ofPhaseolus coccineus: Growth and microanatomy

During early embryogeny, the development of the suspensor is rapid both in terms of size and fresh weight; structural differentiation can be observed as early as the proembryo stage with the formation of wall ingrowths. Ingrowths first appear in the outer wall of the suspensor cells adjacent to the integumentary tapetum, soon ingrowths begin to form in the inner suspensor cells as well. A basal-terminal gradation in nuclear size exists, with the largest nuclei in the basal suspensor cells. Cytologically, the suspensor cells appear to be very active, especially when the embryo reaches heart stage. Initially, the development of the embryo proper lags behind the suspensor, but its size and fresh weight increase rapidly as development proceeds. The volume of the liquid endosperm rises most rapidly during the late heart stage; and it is absorbed soon after. A cellular endospermic sheath surrounds the embryo, separating it from the liquid endosperm. Structural differentiation also occurs in the cellular endosperm cells with the formation of wall ingrowths in those cells that abut directly onto the integumentary tapetum. Both the suspensor and the cellular endosperm appear to remain active through the maturation of the seed. Storage bodies are formed in the cotyledons as well as in the embryonic axis. In the suspensor and the cellular endosperm, starch grains and lipid bodies can be found at the maturation stage.

High frequency induction of somatic embryos in cultured leaf expiants of Coffea arabica L.

Summary High frequency somatic embryo induction (HFSE) and subsequent plantlet development are reported for the first time in cultures of Coffea arabica leaf tissue expiants. The highest number of replicates of the various treatments with HFSE was observed in experiments where primary cultures were grown on a «conditioning medium» containing basal medium (BM), 3% sucrose, and varying concentrations of 2,4-D and kinetin for 7 weeks; subcultured on conditioning medium of the same formulation with a reduction in the concentration of BM salts (x/2) for 4 weeks. Thereafter, tissues were subcultured on «induction medium» consisting of x/2 inorganic salts and an increased concentration of KNO 3 (2x), BM organics, and kinetin and NAA at a concentration ratio of 2.3/0.27 μM. Micromolar concentration ratios of kinetin and 2,4-D at 18.4/4.5, 18.4/18.0 and 36.8/ 4.5 μM in the «conditioning medium» used for tissues during primary and secondary culture result in the production of optimal HFSE when such tissues are subcultured onto «induction medium». Between 50–60% of the replicate cultures contained tissues with HFSE. Low frequency somatic embryo development (LFSE) was observed in tissues cultured on «induction medium» derived from cultures initially grown on a «conditioning medium» containing NAA and kinetin or NAA and kinetin supplemented with undefined growth factors (liquid endosperm of coconut, casein hydrolysate, yeast extract, and leaf extracts of tabacco and Kalanchoe spp.).

Abscisic Acid Metabolism by a Cell-free Preparation from Echinocystis lobata Liquid Endoserum

A cell-free enzyme system capable of metabolizing abscisic acid has been obtained from Eastern Wild Cucumber (Echinocystis lobata Michx.) liquid endosperm. The reaction products were determined to be phaseic acid (PA) and dihydrophaseic acid (DPA) by co-chromatography on thin layer chromatograms as the free acids, methyl esters, and their respective oxidation or reduction products. The crude enzyme preparation was separated by centrifugation into a particulate abscisic acid (ABA)-hydroxylating activity and a soluble PA-reducing activity. The particulate ABA-hydroxylating enzyme showed a requirement for O(2) and NADPH, inhibition by CO, and high substrate specificity for (+)-ABA. Acetylation of short term incubation mixtures gave evidence for the presence of 6'-hydroxymethyl-ABA as an intermediate in PA formation. Determinations of endogenous ABA and DPA concentrations suggest that the ABA-hydroxylating and PA-reducing enzymes are extensively metabolizing ABA in the intact E. lobata seed.

The Effect of Coconut Milk on the Germination and Growth of Spores of Nephrolepis hirsutula

The liquid endosperm of coconuts (generally referred to as coconut milk) has been used as a basal medium in many studies of the growth of angiosperm tissues. It has been used as a supplement to the medium in only a few investigations of the growth of fern tissues (Kato, 1964). Since fern tissues are retatively easy to grow in culture, there is no necessity to use supplements such as liquid coconut endosperm. However, in angiosperms the use of coconut endosperm has resulted in some very dramatic changes in the development of tissues (Steward et al., 1964). This investigation was designed to study whether or not coconut endosperm brought about any changes in the development of the gametophytes of Nephrolepis hirsutula.

Seed and Pod Wall Development inPisum sativum, L. in Relation to Extracted and Applied Hormones

Developing fruits of Pisurn sativum, L., cv. 'Alaska', contain relatively large amounts of hor mones, mainly concentrated in the embryos and liquid endosperm. A close relationship can be demonstrated between changes in extractable amounts of gibberellins (mainly GA20), auxins (methyl 4-chloroindol-3yl acetate and probably 4-chloroindol-3yl acetic acid), and abscisic acid, and changes in growth rates of both the pod wall and seeds. Growth of the pod wall appears to depend largely on hormones supplied by the seeds. Marked changes in the germination capacity of the maturing seeds are closely associated with changes in extractable amounts of methyl-4-chloroindol-3yl acetate and abscisic acid. It is believed that high concentrations of these substances in the embryo, rather than any restriction imposed by the testa, may prevent precocious germination of the seeds.

Organic Nutrients in the Media for Propagation of Cymbidium in vitro

AbstractProtocorms of Cymbidium (Orchidaceae) were grown on media containing different organic nutrients. Of the sugars tested sucrose was better than maltose, glucose and fructose, and sucrose had an optimum concentration of 3 to 4 %. D‐Mannose was significantly less effective than the other sugars. The amino acid mixtures casamino acids (casein hydrolysate) and tryptone increased growth while yeast extract was inhibitory and malt extract without effect. Optimal concentrations were 2 to 3 g · l‐1 casamino acids and 3 to 4 g · l‐1 tryptone. It was to some extent possible to substitute the amino acid mixtures with a single amino acid (glutamine at 300 mg · l‐1). Arginine was inhibitory and asparagine was without any effect. Vitamins proved to be unnecessary although there was a tendency towards increased growth with nicotinic acid and meso‐inositol. Purines and pyrimidines were added to the medium but with no effect. Liquid endosperm from coconuts (10 to 15%) increased growth while the liquid endosperm from Aesculus hippocastanum was inhibitory. On the basis of these results a revised medium is proposed for the in vitro propagation of Cymbidium.

Totipotency and embryogenesis in plant cell and tissue cultures.

An important development in the field of plant cell and tissue culture has been the demonstration in the past decade of the totipotency of higher plant cells. Isolated single cells were first successfully grown on a nurse tissue separated by a filter paper and gave rise to a callus tissue. Later, completely isolated single cells of tobacco were grown in microchambers to form small clumps of cells which then could be differentiated to form adult tobacco plants. Indirect evidence of the totipotency of higher plant cells has also been provided in a number of other plants. Embryo-like structures (or embryoids) or whole plants, or both, have been obtained from such highly differentiated cells as the pollen grains (gametic and haploid), photosynthetic palisade cells in leaves, epidermal cells from the hypocytyl, and the triploid endosperm cells; all of these cell types perform very highly specialized functions in the plant. Plant protoplasts (cell wall is digested with enzymes) have also been cultured to give rise to normal adult plants. In many instances embryoids have been produced in vitro from several species of flowering plants which do not show such asexual activity in nature. These embryoids are normally indistinguishable morphologically from embryos produced by gametic fusion, often follow the same pattern of cell divisions and differentiation as the developing zygote, and are economically important as they provide clonal populations. Early work in this area emphasized the necessity of dissociating tissues into single cells and providing a nutritional environment identical to that of the zygote in the embryo sac (usually by supplementing the medium with liquid endosperm from coconuts), before the cells could be released morphogenetically to express their totipotency by forming embryoids. Much of the recent work, however, has shown that perfect development of embryoids can be obtained in completely synthetic media in callus tissues as well as in suspension cultures.

Maize endopeptidase: genetic control, chemical characterization, and relationship to an endogenous trypsin inhibitor.

A single form of endopeptidase (EP-1) was found to be present at all stages of development and differentiation in all tissues of inbred maize. This endopeptidase occurs as two electrophoretically distinct variants which exist in different inbred maize lines. The gene coding for this endopeptidase has been tentatively located at or near the Y1 locus on chromosome 6. The EP-1 variants are under the control of two codominant alleles (Ep1A and Ep1B) at the Ep1 locus. The two endopeptidase variants are similar with respect to molecular weight, heat stability, Km, and metal ion inhibition, but are distinguishable by distinct isoelectric points as well as by different mobilities on starch gel electrophoresis. All attempts to hybridize the variants for purposes of determining subunit structure have failed. The endopeptidase is not inhibited by endogenous maize bovine trypsin inhibitor. During the development of seedlings, the endopeptidase is most active in immature liquid endosperm and in scutella, while the maize trypsin inhibitor is highest in starchy endosperm of mature kernels.

Survey of Occurrences of Liquid or Soft Endosperm in Grass Genera

Survey of Occurrences of Liquid or Soft Endosperm in Grass Genera

Nodulation of soybean as influenced by the liquid endosperm of coconut

The liquid endosperm of coconut showed a stimulatory effect on the number and volume of nodules of soybean (var. Bragg) inoculated with peat based culture ofRhizobium japonicum S.B. 16. Coconut water stimulated the growths ofRhizopus arrhizus on nodules which, in its turn, was shown to increase the growth ofR. japonicum.

Identification and genetic control of starch-degrading enzymes in maize endosperm.

Three starch-degrading enzymes from liquid endosperm of maize have been separated by means of horizontal acrylamide gel electrophoresis. The three enzymes are tentatively identified as α-amylase (zone 1), β-amylase (zone 2), and α-glucan phosphorylase (zone 3). Electrophoretic variants of these enzymes were found among ten inbred strains examined. Results of genetic crosses with respect to zone 2 amylase show that it is controlled by a pair of alleles (Amy-2 A and Amy-2 B) acting without dominance. It further appears that Amy-2 and Ct (catalase) are linked with 5% recombination frequency.