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Showing papers on "Endosperm published in 1987"


Journal ArticleDOI
01 Aug 1987-Planta
TL;DR: Simultaneous incubation of de-embryonated endosperms and isolated axes showed that wild-type embryos contain and endosperm-weakening factor that is absent in ga-1 axes and is probably a GA, which facilitates germination in tomato seeds by weakening the mechanical restraint of the endOSperm cells to permit radicle protrusion.
Abstract: The germination of seeds of tomato [Lycopersicon esculentum (L.) Mill.] cv. Moneymaker has been compared with that of seeds of the gibberellin-deficient dwarf-mutant line ga-1, induced in the same genetic background. Germination of tomato seeds was absolutely dependent on the presence of either endogenous or exogenous gibberellins (GAs). Gibberellin A4+7 was 1000-fold more active than commercial gibberellic acid in inducing germination of the ga-1 seeds. Red light, a preincubation at 2°C, and ethylene did not stimulate germination of ga-1 seeds in the absence of GA4+7; however, fusicoccin did stimulate germination independently. Removal of the endosperm and testa layers opposite the radicle tip caused germination of ga-1 seeds in water. The seedlings and plants that develop from the detipped ga-1 seeds exhibited the extreme dwarfy phenotype that is normal to this genotype. Measurements of the mechanical resistance of the surrounding layers showed that the major action of GAs was directed to the weakening of the endosperm cells around the radicle tip. In wild-type seeds this weakening occurred in water before radicle protrusion. In ga-1 seeds a similar event was dependent on GA4+7, while fusicoccin also had some activity. Simultaneous incubation of de-embryonated endosperms and isolated axes showed that wild-type embryos contain and endosperm-weakening factor that is absent in ga-1 axes and is probably a GA. Thus, an endogenous GA facilitates germination in tomato seeds by weakening the mechanical restraint of the endosperm cells to permit radicle protrusion.

345 citations


Journal ArticleDOI
TL;DR: A deletion series of the LMW glutenin sequence indicated that sequences present between 326 bp and 160 bp upstream of the transcription start point are necessary to confer endosperm‐specific CAT activity.
Abstract: The developing cereal grain accumulates large quantities of proteins which are unique to the endosperm tissue. The DNA sequences which determine their endosperm-specific expression have not yet been identified. In the absence of a suitable transformation-regeneration system for cereals, we have investigated whether chimaeric genes consisting of low mol. wt (LMW) and high mol. wt (HMW) glutenin gene upstream sequences coupled to the coding region of the bacterial chloramphenicol acetyl transferase (CAT) gene could be specifically expressed in transgenic tobacco. The fusions, made in a Ti-derived binary vector, were introduced into tobacco via Agrobacterium tumefaciens-mediated transformation and their activity assayed. Both the LMW and HMW glutenin chimaeric genes exhibited endosperm-specific CAT activity in the transformed plants. In addition, a deletion series of the LMW glutenin sequence indicated that sequences present between 326 bp and 160 bp upstream of the transcription start point are necessary to confer endosperm-specific CAT activity.

218 citations


Journal ArticleDOI
TL;DR: In this article, the major cereal dietary fibre components, pentosans and β-glucans, were measured in whole grains of two varieties each of wheat, barley, oats and rye and in the endosperms from these grains.

189 citations


Journal ArticleDOI
TL;DR: Southern blotting of genomic DNA demonstrates that beta-amylase is encoded by a small gene family, while cDNA sequence analysis indicates the presence of at least two types of mRNA in the endosperm.
Abstract: The primary structure of barley endosperm beta-amylase, an enzyme which catalyses the liberation of maltose from 1,4-alpha-D-glucans, has been deduced from the nucleotide sequence of a cloned full-length cDNA. The mRNA is 1754 nucleotides long [excluding the poly(A) tail] and codes for a polypeptide of 535 amino acids with a relative molecular mass of 59,663. The deduced amino acid sequence was compared with the sequences of ten peptides obtained from the purified enzyme and unambiguous identification was obtained. The N-terminal region of the deduced sequence was identical to a 12-residue cyanogen-bromide-peptide sequence, indicating that beta-amylase is synthesized as the mature protein. A graphic matrix homology plot shows four glycine-rich repeats, each of 11 residues, preceding the C-terminus. Southern blotting of genomic DNA demonstrates that beta-amylase is encoded by a small gene family, while cDNA sequence analysis indicates the presence of at least two types of mRNA in the endosperm. Dot and northern blot analysis show that Hiproly barley contains greatly increased levels of beta-amylase mRNA compared to the normal cultivar Sundance, whereas Riso mutant 1508 contains only trace amounts. These results correlate well with the deposition of beta-amylase during endosperm development in these lines. Low but similar amounts of beta-amylase mRNAs sequences were detected in leaves and shoots from normal and mutant barleys, demonstrating that the mutant lys3a (1508) and lysl (Hiproly) genes do not affect the expression of beta-amylase in these tissues.

162 citations


Journal ArticleDOI
TL;DR: The major effect of proteolysis was to enhance enzyme activity in the absence of added activator while greatly decreasing its sensitivity to the allosteric effectors 3-P-glycerate and inorganic phosphate.
Abstract: ADPglucose pyrophosphorylase from developing endosperm tissue of starchy maize (Zea mays) was purified 88-fold to a specific activity of 34 micromoles α-glucose-1-P produced per minute per milligram protein. Rabbit antiserum to purified spinach leaf ADPglucose pyrophosphorylase was able to inhibit pyrophosphorolysis activity of the purified enzyme by up to 90%. The final preparation yielded four major protein staining bands following sodium dodecyl sulfate polyacrylamide gel electrophoresis. When analyzed by Western blot hybridization only the fastest migrating, 54 kilodaltons, protein staining band cross-reacted with affinity purified rabbit antispinach leaf ADPglucose pyrophosphorylase immunoglobulin. The molecular mass of the native enzyme was estimated to be 230 kilodaltons. Thus, maize endosperm ADPglucose pyrophosphorylase appears to be comprised of four subunits. This is in contrast to the respective subunit and native molecular masses of 96 and 400 kilodaltons reported for a preparation of maize endosperm ADPglucose pyrophosphorylase (Fuchs RL and JO Smith 1979 Biochim Biophys Acta 556: 40-48). Proteolytic degradation of maize endosperm ADPglucose pyrophosphorylase appears to occur during incubation of crude extracts at 30°C or during the partial purification of the enzyme according to a previously reported procedure (DB Dickinson, J Preiss 1969 Arch Biochem Biophys 130: 119-128). The progressive appearance of a 53 kilodalton antigenic peptide suggested the loss of a 1 kilodalton proteolytic fragment from the 54 kilodalton subunit. The complete conservation of the 54 kilodalton subunit structure following extraction of the enzyme in the presence of phenylmethylsulfonyl fluoride and/or chymostain was observed. The allosteric and catalytic properties of the partially purified proteolytic degraded versus nondegraded enzyme were compared. The major effect of proteolysis was to enhance enzyme activity in the absence of added activator while greatly decreasing its sensitivity to the allosteric effectors 3-P-glycerate and inorganic phosphate.

161 citations


Journal ArticleDOI
TL;DR: Electron microscope immunogold localization of the zein expressed in embryo and endosperm tissue indicates that the monocot protein accumulates in the crystalloid component of vacuolar protein bodies.
Abstract: The maize 15-Kd zein structural gene was placed under the regulation of French bean beta-phaseolin gene flanking regions Agrobacterium tumefaciens-mediated transformation was used to insert the chimeric phaseolin-zein gene into the tobacco genome Transgenic plants synthesized zein in a tissue-specific manner during the latter half of seed development Transcription of the chimeric gene was initiated in phaseolin-derived sequences, and was terminated within the phaseolin gene 3' flanking region Both zein- and phaseolin-derived polyadenylation signals were used in the processing of zein RNA in transgenic plant seeds Zein accumulation, though subject to an 80-fold variation among 19 plants tested, could reach as much as 16% of the total seed protein in several plants In developing tobacco seeds, zein was correctly processed by the removal of a 20-amino-acid signal peptide Electron microscope immunogold localization of the zein expressed in embryo and endosperm tissue indicates that the monocot protein accumulates in the crystalloid component of vacuolar protein bodies The density of gold label over the protein bodies is several fold greater in the embryo than the endosperm Zein is found in roots, hypocotyls and cotyledons of germinating transgenic tobacco seeds

135 citations


Journal ArticleDOI
TL;DR: In this paper, the authors measured the amylose and lysophospholipid content of wheat granules using a Coulter Counter with 100-channel analyser, and determined the composition of whole wheat and starch granule compositions.

118 citations


Journal ArticleDOI
TL;DR: Invertase (β-fructofuranoside fructohydrolase, EC 3.2.1.26) activity in developing maize was separated into soluble and particulate forms, and Histochemical staining of cell wall preparations for invertase activity suggested that the particulate invert enzyme is associated with the cell wall.
Abstract: Invertase (β-fructofuranoside fructohydrolase, EC 3.2.1.26) activity in developing maize (Zea mays L. inbred W64A) was separated into soluble and particulate forms. The particulate form was solubilized by treatment with 1 M NaCl or with other salts. However, CaCl2 inhibited invertase activity, and neither detergents nor 0.5 M methyl mannoside were effective in solubilizing the invertase activity. The soluble and particulate invertases were both glycoproteins, both had pH optima of 5.0 and Km values for sucrose of 2.83 and 1.84 mM, respectively. The apparent molecular weight of salt-solubilized invertase was 40 kDa. Gel filtration of the soluble invertase showed multiple peaks with apparent molecular weights ranging from 750 kDa to over 9 000 kDa. Histochemical staining of cell wall preparations for invertase activity suggested that the particulate invertase is associated with the cell wall. Also, nearly all the invertase activity was localized in the basal endosperm and pedicel tissues, which are sites of sugar transport. No invertase activity was found in the upper endosperm, the embryo or in the placento-chalazal tissue. In contrast, sucrose synthase (EC 2.4.1.13) activity was found primarily in the embryo and the upper endosperm, which are areas of active biosynthesis of storage compounds.

117 citations


Book ChapterDOI
01 Jan 1987
TL;DR: In this paper, the authors discussed the influence of corn kernel lipids on economics and health of animals and humans, including neutral and polar acyl lipids, sterols, tocols, and carotenoids.
Abstract: Although the content of lipids in corn kernels is not high compared to oilseeds, the impact of such lipids on economics and health of animal and human is significant because of the high volume of corn produced and utilized in the United States. Various classes of lipids present in corn kernels, such as neutral and polar acyl lipids, sterols, tocols, and carotenoids, are presented in this chapter. The natural variation of these lipids and their genetic modification to improve compositional traits are discussed. There are distinct lipid distribution patterns in corn kernel's endosperm, germ, pericarp, and tip cap. About 80% of total kernel lipids is in the germ, and the remaining is mainly in the endosperm and aleurone layer. About 90% of the kernel carotenoids is in the endosperm, and the lipids in the aleurone layer have very high concentration of the unique ferulic acid esters of the phytosterols (about 85% of the total). Thus, corn germ oil's lipid class composition is very different from oils extracted from the entire kernels using a solvent that is more polar than hexane and from the corn fiber oil. Corn starch, particularly the amylose fraction, is naturally complexed with monoacyl lipids. Such property has been used to create a slowly digestable corn starch product. Enzymatically derived lipids and hormones are important class of oxilipins that are signaling molecules and are involved in plant's defense against pathogens. High-value lipid products from corn milling and dry-grind ethanol fermentation, such as corn fiber oil and distiller's corn oil, can be produced more efficiently to improve the economics of the corn processing industry. Other challenges and future directions of research and development are also discussed.

87 citations


Journal ArticleDOI
01 Jan 1987-Gene
TL;DR: A collection of cDNA clones, corresponding to a group of maize endosperm proteins classified in the glutelin-2 and zein-2 subfractions, has been identified and characterized and an hypothesis is proposed on how sequence diversity may have been generated in this particular class of plant proteins.

85 citations


Journal ArticleDOI
TL;DR: In this article, the distribution of abscisic acid within maize kernels was studied in kernels from nontreated plants, from plants in which assimilate supply had been altered by source/sink manipulations, and in kernels cultured in vitro on ABA-free media.
Abstract: The distribution of abscisic acid (ABA) within maize (Zea mays L.) kernels was studied in kernels from nontreated plants, from plants in which assimilate supply had been altered by source/sink manipulations, and in kernels cultured in vitro on ABA-free media. Prior to growth of the embryo, both the pedicel/placento-chalazal complex and the endosperm contained high concentration of ABA; however, the quantity of ABA in these tissues declined as the concentration in the embryo increased during the early stages of embryo growth. Peaks in the levels of ABA appeared to occur prior to and not concurrent with physiological events during grain filling. During most of the grain filling period, ABA concentration in the embryo was higher than that found in other kernel components. Altering assimilate supply by partial defoliation at two stages of development resulted in variable and transient effects on the relative distribution and concentration of ABA in kernel components. The concentration and distribution of ABA among components of kernels grown in vitro was similar to that observed for field-grown kernels. On the basis of these findings, in situ synthesis of ABA by kernel components is implicated and the putative role of ABA in the regulation of kernel development is discussed.

Journal ArticleDOI
TL;DR: A cytological study of wheat ovaries fixed 48 h after pollination showed that the wheat genotypes ‘Highbury’ and ‘Chinese Spring’ were crossable with ‘Seneca 60’ maize, but all three wheat x maize combinations were karyotypically unstable and rapidly eliminated maize chromosomes to produce haploid wheat embryos.
Abstract: Dominant alleles of the Kr1 and Kr2 genes reduce the crossability of hexaploid wheat with many alien species, including rye and Hordeum bulbosum, with Kr1 having the greater effect. However, a cytological study of wheat ovaries fixed 48 h after pollination showed that the wheat genotypes ‘Highbury’ (kr1, Kr2) and ‘Chinese Spring (Hope 5B)’ (kr1, kr2) were crossable with ‘Seneca 60’ maize, fertilization occurring in 14.4 and 30.7% of embryo sacs respectively. The latter figure was similar to the 29.7% fertilization found in ‘Chinese Spring’ (kr1, kr2). Most embryo sacs in which fertilization occurred contained an embryo but lacked an endosperm and where an endosperm was formed it was usually highly aberrant. All three wheat x maize combinations were karyotypically unstable and rapidly eliminated maize chromosomes to produce haploid wheat embryos.

Journal ArticleDOI
01 Jul 1987-Planta
TL;DR: Germinated vp-1 embryos were less sensitive to growth inhibition by ABA or mannitol than germinating wild-type embryos, and their transpiration rates were reduced in response to A BA or water shortage.
Abstract: Seed development was investigated in kernels of developing wild-type and viviparous (vp-1) Zea mays L Embryos and endosperm of wild-type kernels began to dehydrate at approx 35 d after pollination (DAP); viviparous embryos did not desiccate but accumulated fresh weight via coleoptile growth in the caryopses Concentrations of endogenous abscisic acid (ABA) in the embryo were relatively high early in development, being approx 150 ng·g(-1) fresh weight at 20 DAP The ABA content declined thereafter, falling to approx 50 ng·g(-1) at 30 DAP Endosperm ABA content was always low, being less than 20 ng·g(-1) There were no differences between wild-type and vp-1 tissues Immature kernels did not germinate when removed from the ear until late in development The ability to germinate was correlated with decreasing moisture content in the endosperm at the time of removal; premature drying of immature kernels resulted in greatly increased germination following imbibition Excised embryos germinated precociously when removed from the endosperm as early as 25 DAP Such germination could be prevented by treatment with 10(-5) M ABA or by lowering the solute potential (Ψs) of the medium with 03 M mannitol Treatment of excised embryos with ABA led to internal ABA concentrations comparable to those in embryos in which germination was inhibited in situ Mannitol treatment did not have this effect, although water-deficit stress of excised embryos resulted in substantial ABA production Germinated vp-1 embryos were less sensitive to growth inhibition by ABA or mannitol than germinating wild-type embryos The vp-1 seedlings were not wilty and their transpiration rates were reduced in response to ABA or water shortage

Journal ArticleDOI
TL;DR: Using Agrobacterium‐mediated transformation, two genes for phytohemagglutinin‐L, the lectin seed protein of the common bean Phaseolus vulgaris, were stably integrated into the tobacco genome and it is concluded that the signals for temporal and spatial regulation of the dlec2 gene are present in the DNA fragment used for transformation.
Abstract: Using Agrobacterium-mediated transformation, two genes for phytohemagglutinin-L (PHA-L), the lectin seed protein of the common bean Phaseolus vulgaris, were stably integrated into the tobacco genome. The two alleles for PHA-L, dlec2 and pdlec2, were obtained from a normal cultivar (Greensleeves) and a lectin-deficient cultivar (Pinto) respectively. In the bean embryos, the expression of dlec2 is 30 times greater than the expression of pdlec2. In the dlec2-transformed tobacco, PHA-L accumulated specifically in the seeds at the same stages as the tobacco seed storage proteins and was degraded after germination. PHA-L was found in the embryo, and at a 5–7 times lower concentration in the endosperm tissue of the mature tobacco seeds. No PHA could be detected in other parts of the plants. We conclude that the signals for temporal and spatial regulation of the dlec2 gene are present in the DNA fragment used for transformation. Transformation with the second PHA-L allele pdlec2 from the cultivar Pinto caused the accumulation of about 50 times less PHA-L in tobacco seeds when compared to dlec2. We conclude from analyzing the 5' sequences of dlec2 and Pdlec2 that the low expression phenotype of the Pdlec2 allele could be due to the absence or mutation of a cis-acting element carried by the dlec2 fragment.

Journal ArticleDOI
TL;DR: The extent to which wheat grain growth is dependent on transport pool solute concentration was investigated by the use of illumination and partial grain removal to vary solute concentrations in the sieve tube and endosperm cavity saps of the wheat ear, with apparent unresponsiveness of grain growth rate to increased cavity sap sucrose concentration.
Abstract: The extent to which wheat grain growth is dependent on transport pool solute concentration was investigated by the use of illumination and partial grain removal to vary solute concentrations in the sieve tube and endosperm cavity saps of the wheat ear (Triticum aestivum L.). Short-term grain growth rates were estimated indirectly from the product of phloem area, sieve tube sap concentration, and (32)P translocation velocity. On a per grain basis, calculated rates of mass transport through the peduncle were fairly constant over a substantial range in other transport parameters (i.e. velocity, concentration, phloem area, and grain number). The rates were about 40% higher than expected; this probably reflects some unavoidable bias on faster-moving tracer in the velocity estimates. Sieve tube sap concentration increased in all experiments (by 20 to 64%), with a concomitant decline in velocity (to as low as 8% of the initial value). Endosperm cavity sucrose concentration also increased in all experiments, but cavity sap osmolality and total amino acid concentration remained nearly constant. No evidence was found for an increase in the rate of mass transport per grain through the peduncle in response to the treatments. This apparent unresponsiveness of grain growth rate to increased cavity sap sucrose concentration conflicts with earlier in vitro endosperm studies showing that sucrose uptake increased with increasing external sucrose concentration up to 150 to 200 millimolar.

Journal ArticleDOI
TL;DR: Water uptake during the germination of UC 82B tomato seeds was triphasic and it is suggested that embryo water content is restricted by the constraint on embryo expansion caused by the enclosing endosperm tissue.
Abstract: Water uptake during the germination of UC 82B tomato seeds was triphasic. Seed Ψ measurements indicated that phase I imbibition occurred because of the large Ψ gradient between the seed and the imbibition solution (water). During phase II the seed Ψ was in equilibrium with the water. Phase III water uptake recommenced with the onset of radicle emergence without changes in Ψ or Ψπ. Changes in embryo water content were also triphasic. During phase II the embryo Ψ remained at - 1.5 MPa, not in equilibrium with the imbibing solution. At radicle emergence it was - 0.8 MPa and rose to -0.3 MPa as the radicle elongated. There was no evidence of a lowering of embryo Ψπ nor of a build up of Ψp prior to radicle emergence. Water uptake studies with excised embryos indicated that, within the seed, the enclosing tissues prevented the embryo from taking up water. It is suggested that embryo water content is restricted by the constraint on embryo expansion caused by the enclosing endosperm tissue. Lowering of embryo Ψπ to build up Ψp is not necessary for radicle emergence. The control of germination may lie in the mechanism which leads to weakening of this mechanical restraint of the endosperm.

Journal ArticleDOI
TL;DR: Two mutants for rice storage protein in the starchy endosperm, 13b-L and 57-H, were crossed with their original variety, Kinmaze and the results suggest that esp-1 and esp-2 are located on chromosomes 10 and 9, respectively.
Abstract: Two mutants for rice storage protein in the starchy endosperm, 13b-L and 57-H, were crossed with their original variety, Kinmaze. From the results obtained in the F1 and F2 seeds, it was concluded that 13b-L and 57-H are controlled by single recessive genes, which were designated as esp-1 and esp-2, respectively. The SDS-PAGE indicates that both mutant genes are regulatory genes for the protein bodies. The segregation ratio in F2 of the cross between esp-1 and trisomic type F and the cross between esp-2 and trisomic type G fitted that of a trisomic segregation. These results suggest that esp-1 and esp-2 are located on chromosomes 10 and 9, respectively.

Journal ArticleDOI
TL;DR: Fructose and glucose, which are present in maize endosperm as the products of invertase, could inhibit sucrose synthase, especially in basal regions of the kernel where hexosesmay accumulate.

Journal ArticleDOI
TL;DR: It is postulated that ketose reductase may function to metabolize some of the fructose produced during sucrose degradation in maize endosperm, but the metabolic fate of sorbitol produced by this reaction is not known.
Abstract: Ketose reductase (NAD-dependent polyol dehydrogenase EC 1.1.1.14) activity, which catalyzes the NADH-dependent reduction of fructose to sorbitol (d-glucitol), was detected in developing maize (Zea mays L.) endosperm, purified 104-fold from this tissue, and partially characterized. Product analysis by high performance liquid chromatography confirmed that the enzyme-catalyzed reaction was freely reversible. In maize endosperm, 15 days after pollination, ketose reductase activity was of the same order of magnitude as sucrose synthase activity, which produces fructose during sucrose degradation. Other enzymes of hexose metabolism detected in maize endosperm were present in activities of only 1 to 3% of the sucrose synthase activity. CaCl2, MgCl2, and MnCl2 stimulated ketose reductase activity 7-, 6-, and 2-fold, respectively, but had little effect on NAD-dependent polyol dehydrogenation (the reverse reaction). The pH optimums for ketose reductase and polyol dehydrogenase reactions were 6.0 and 9.0, respectively. Km values were 136 millimolar fructose and 8.4 millimolar sorbitol. The molecular mass of ketose reductase was estimated to be 78 kilodaltons by gel filtration. It is postulated that ketose reductase may function to metabolize some of the fructose produced during sucrose degradation in maize endosperm, but the metabolic fate of sorbitol produced by this reaction is not known.

Journal ArticleDOI
TL;DR: Uptake of FS into maize endosperm without Hydrolysis suggests that despite the presence of invertase in maternal tissues and the hydrolysis of a large percentage of sucrose unloaded from the phloem, hexoses are not specifically needed for uptake into maizeendosperm.
Abstract: 1′-Fluorosucrose (FS), a sucrose analog resistant to hydrolysis by invertase, was transported from husk leaves into maize (Zea mays L., Pioneer Hybrid 3320) kernels with the same magnitude and kinetics as sucrose. 14C-Label from [14C]FS and [14C]sucrose in separate experiments was distributed similarly between the pedicel, endosperm, and embryo with time. FS passed through maternal tissue and was absorbed intact into the endosperm where it was metabolized and used in synthesis of sucrose and methanol-chloroform-water insolubles. Accumulation of [14C] sucrose from supplied [14C]glucosyl-FS indicated that the glucose moiety from the breakdown of sucrose (here FS), which normally occurs in the process of starch synthesis in maize endosperm, was available to the pool of substrates for resynthesis of sucrose. Uptake of FS into maize endosperm without hydrolysis suggests that despite the presence of invertase in maternal tissues and the hydrolysis of a large percentage of sucrose unloaded from the phloem, hexoses are not specifically needed for uptake into maize endosperm.

Journal ArticleDOI
TL;DR: The results described in this paper show that during early growth of castor seeds the lipid bodies acquire a lipase which is active at neutral pH values and adequately accounts for the known rate of triacylglycerol hydrolysis in vivo.
Abstract: The membranes of lipid bodies from the endosperm of seeds of Ricinus communis have long been known to contain an acid lipase (triacylglycerol acyl hydrolase, EC 3.1.1.3). The means by which fat hydrolysis is initiated and controlled in the endosperm of the young seedling are not yet understood, although it is generally assumed that the acid lipase is the enzyme responsible for the conversion of stored triacylglycerols to fatty acids and glycerol. However, the enzyme from seeds is not an effective catalyst at cytoplasmic pH since it has a pH optimum at 4.5 and is virtually inactive above pH 6.0. The results described in this paper show that during early growth of castor seeds the lipid bodies acquire a lipase which is active at neutral pH values. The lipase is absent from dry seeds, appears at day 3, and increases rapidly in activity until day 5. The pattern of appearance of the lipase mirrors that of other enzymes involved in the conversion of fat to sugar. The lipase is stimulated 40-fold by 30 micromolar free Ca(2+) and the activity at pH 7.0 to 7.5 adequately accounts for the known rate of triacylglycerol hydrolysis in vivo.

01 Jan 1987
TL;DR: The in vitro culture of zygotic embryos solves the problems encountered in transporting and storing coconut seeds (Cocos nucifera L.). especially when obtained under field collecting conditions.
Abstract: The in vitro culture of zygotic embryos solves the problems encountered in transporting and storing coconut seeds (Cocos nucifera L.). especially when obtained under field collecting conditions. Embryo sampling and short-term storage methods have been developed. Direct inoculation into culture on media, enabling embryo growth under axenic conditions. has been successfully carried out under field collecting conditions. An alternative method holds embryos in endosperm cores in a salt solution for brief periods before excision and inoculation into culture in a laboratory. The techniques and equipment used are described in this paper, as well as the subsequent development of the ernbryos and the transfer of plants to natural growing conditions.

Journal ArticleDOI
01 Oct 1987-Genetics
TL;DR: It is postulated that this interacting system is analogous to aneuploid effects in diploid tissues but exhibits unique properties because of the evolutionary history and triploid condition of the endosperm.
Abstract: Crosses involving certain B-A translocations produce a reduced size of endosperm when those regions of the A chromosomes are missing in the sperm that fertilizes the polar nuclei. Previous studies involving the long arm of chromosome 10 showed that additional copies of this segment introduced through the maternal side could not rescue the reduced size phenotype conditioned by the corresponding deficiency in the paternal gamete. In this paper, experiments are described showing that other segments introduced maternally produce an even smaller kernel when fertilized by a sperm missing the same A chromosome segment or other ones that carry factors affecting endosperm size.—The example analyzed in detail involves reciprocal crosses between TB-4Sa and TB-10L19 . Extra doses of 4S enhance the small kernel effect normally produced by TB-10L19 . The additional copies of 4S have no effect on kernel mass when the 10L segment is present in the paternal contribution to the endosperm. The maternal enhancement by 4S is also effective with crosses by TB-1La but not by TB-1Sb . A survey of inter se crosses of B-A translocations shows that, when the maternal enhancement occurs, it is confined to those regions that themselves give a small kernel effect when used as a male. This correlation is strengthened by the observations that TB-10L19 enhances the small kernel effect of TB-1Sb , but TB-10L32 will not. Since these two B-10L translocations span the best localized small kernel effect region, this result supports the correlation of maternal enhancement regions with the paternal small kernel effect ones.—Because the enhancement can be attributed to a dosage effect and because the enhancement regions are coincident with the small kernel segments, it is postulated that this interacting system is analogous to aneuploid effects in diploid tissues but exhibits unique properties because of the evolutionary history and triploid condition of the endosperm.

Journal ArticleDOI
TL;DR: Metabolic inhibitor studies using carbonylcyanide-m-chlorophenylhydrazone, sodium cyanide, and dinitrophenol and estimates of Q(10) suggest that the transport of sugars into the developing maize endosperm is a passive process, and the conversion of sucrose to glucose and fructose may play a role in sugar absorption byendosperm.
Abstract: Short-term transport studies were conducted using excised whole Zea mays kernels incubated in buffered solutions containing radiolabeled sugars. Following incubation, endosperms were removed and rates of net 14C-sugar uptake were determined. Endogenous sugar gradients of the kernel were estimated by measuring sugar concentrations in cell sap collected from the pedicel and endosperm. A sugar concentration gradient from the pedicel to the endosperm was found. Uptake rates of 14C-labeled glucose, fructose, and sucrose were linear over the concentration range of 2 to 200 millimolar. At sugar concentrations greater than 50 millimolar, hexose uptake exceeded sucrose uptake. Metabolic inhibitor studies using carbonylcyanide-m-chlorophenylhydrazone, sodium cyanide, and dinitrophenol and estimates of Q10 suggest that the transport of sugars into the developing maize endosperm is a passive process. Sucrose was hydrolyzed to glucose and fructose during uptake and in the endosperm was either reconverted to sucrose or incorporated into insoluble matter. These data suggest that the conversion of sucrose to glucose and fructose may play a role in sugar absorption by endosperm. Our data do not indicate that sugars are absorbed actively. Sugar uptake by the endosperm may be regulated by the capacity for sugar utilization (i.e. starch synthesis).

Journal ArticleDOI
TL;DR: One of the four major basic salt-soluble proteins in barley with a molecular weight of 28,000 Dalton was shown to be an endochitinase.
Abstract: One of the four major basic salt-soluble proteins in barley with a molecular weight of 28,000 Dalton was shown to be an endochitinase. A partial amino acid sequence has been determined, and strong homology to an endochitinase from bean (Phaseolus vulgaris) is demonstrated.

Journal ArticleDOI
TL;DR: The mutant collection covers mutations in genes participating in all of the developmental phases of the endosperm, including arrest at the proembryo stage, continued cell divisions but no differentiation, and embryos deviating only slightly from the wild type.
Abstract: Eleven Na-azide induced barley shrunken endosperm mutants expressing xenia (sex) were characterized genetically and histologically. All mutants have reduced kernel size with kernel weights ranging from 11 to 57% of the wild type. With one exception, the mutant phenotypes are ascribable to single recessive mutant alleles, giving rise to a ratio of 3∶1 of normal and shrunken kernels on heterozygous plants. One mutant (B10), also monofactorially inherited, shows a gene dosage dependent pattern of expression in the endosperm. Among the 8 mutants tested for allelism, no allelic mutant genes were discovered. By means of translocation mapping, the mutant gene of B10 was localized to the short arm of chromosome 7, and that of B9 to the short arm of chromosome 1. Based on microscopy studies, the mutant kernel phenotypes fall into three classes, viz. mutants with both endosperm and embryo affected and with a non-viable embryo, mutants with both endosperm and embryo affected and with a viable embryo giving rise to plants with a clearly mutant phenotype, and finally mutants with only the endosperm affected and with a normal embryo giving rise to plants with normal phenotype. The mutant collection covers mutations in genes participating in all of the developmental phases of the endosperm, i.e. the passage from syncytial to the cellular endosperm, total lack of aleurone cell formation and disturbance in the pattern of aleurone cell formation. In the starchy endosperm, varying degrees of cell differentiation occur, ranging from slight deviations from wild type to complete loss of starchy endosperm traits. In the embryo, blocks in the major developmental phases are represented in the mutant collection, including arrest at the proembryo stage, continued cell divisions but no differentiation, and embryos deviating only slightly from the wild type.

01 Jan 1987
TL;DR: In this article, Luorosucrose (FS), asucrose analog resistant tohydrolysis by invertase, wastransported fromhuskleaves into maize (ZeamaysL, Pioneer Hybrid 3320) kernels with the samemagnitude andkinetics as sucrose.
Abstract: l'-Fluorosucrose (FS), asucrose analog resistant tohydrolysis by invertase, wastransported fromhuskleaves into maize (ZeamaysL., Pioneer Hybrid 3320) kernels with thesamemagnitude andkinetics as sucrose. "C-Label fromI"CqFS andl"lqsucrose inseparate experiments wasdistributed similarly between thepedicel, endosperm, andembryo with time. FSpassed through maternal tissue andwasabsorbed intact into theendosperm whereitwasmetabolized andusedinsynthesis of sucrose andmethanol-chloroform-water insolubles. Accumulation of114q sucrose fromsupplied I'Cjglucosyl-FS indicated that theglucose moiety fromthebreakdown ofsucrose (here FS), which normally occurs inthe process ofstarch synthesis inmaize endosperm, wasavailable tothepool ofsubstrates forresynthesis ofsucrose. Uptake ofFSinto maize endospermwithout hydrolysis suggests that despite thepresence ofinvertase inmaternal tissues andthehydrolysis ofalarge percentage ofsucrose unloaded fromthephloem, hexoses arenotspecifically needed foruptake into maize endosperm.

Journal ArticleDOI
TL;DR: Protoplasts of eight wild Linum species and 14 genotypes of flax, isolated from different parts of seedlings and from shoot apices, were regenerated to callus in medium V-KM and differentiation like sponge parenchyma, was observed in protoplast-derived tissues of L. usitatissimum.
Abstract: Protoplasts of eight wild Linum species and 14 genotypes of flax, isolated from different parts of seedlings and from shoot apices, were regenerated to callus in medium V-KM (Binding and Nehls 1977). Plant regeneration was obtained in L. alpinum, L. amurense, L. hologynum, L. perenne, L. salsoloides and eight genotypes of L. usitatissimum on agar media B5 (Gamborg et al. 1968), B5C (Binding et al, 1981), MS (Murashige and Skoog 1962) and MSC (MS with 5% coconut endosperm) containing 2.5μM 6-BA. An adventitious embryo was regenerated in L. alpinum. Callus differentiation like sponge parenchyma, was observed in protoplast-derived tissues of L. usitatissimum. Shoots organized roots under slightly divergent conditions in the different species.

Journal ArticleDOI
TL;DR: The abscisic acid (ABA) content of wrinkled pea seed tissues has been quantified during development using multiple-ion-monitoring combined gas chromatography-mass spectrometry and a deuterated internal standard and the production of ABA in pea seeds is discussed in relation to the development of the different seed tissues.
Abstract: Wang, T. L., Cook, S. K., Francis, R. J., Ambrose, M. J. and Hedley, C. L. 1987. An analysis of seed development in Pisum sativum. VI. Abscisic acid accumulation.—J. exp. Bot. 38: 1921-1932. The abscisic acid (ABA) content of wrinkled (rr) pea seed tissues has been quantified during development using multiple-ion-monitoring combined gas chromatography-mass spectrometry and a deuterated internal standard. The level of ABA in the embryo generally increased with increasing cotyledon fresh weight while that in the testa showed a distinct maximum at the time of maximum endosperm volume and the slowing in the growth of the testa. Pods contained relatively little ABA on a fresh weight basis. The total seed ABA content showed a biphasic distribution, the first maximum following the maximum growth rate of the testa and the second that of the embryo. The biphasic distribution of ABA in the pea seed was confirmed using a second pea genotype, near-isogenic to the first except for the r locus, and by the analysis of individual seeds using a radioimmunoassay for ABA. The first maximum was composed mainly of a testa component and the second mainly of an embryo component. When plants were grown in different environments, wrinkled seeds were found to contain slightly more ABA than round (RR) but this was only significant late in development. Immature seeds were capable of metabolizing l'-deoxy ABA to ABA, as deter mined by incorporation of either 3H or 2H, and the metabolite was present mainly in the testa. The production of ABA in pea seeds is discussed in relation to the development of the different seed tissues. Key words—Abscisic acid, peas, seed development. Correspondence to: John Innes Institute, Colney Lane, Norwich NR4 7UH, U.K.

01 Jan 1987
Abstract: Two mutants for rice storage protein in the starchy endosperm, 13b-L and 57-H, were crossed with their original variety, Kinmaze. From the results obtained in the F1 and F2 seeds, it was concluded that 13b-L and 57-H are controlled by single recessive genes, which were designated as esp-1 and esp-2, respectively. The SDS-PAGE indicates that both mutant genes are regulatory genes for the protein bodies. The segregation ratio in F2 of the cross between esp-1 and trisomic type F and the cross between esp-2 and trisomic type G fitted that of a trisomic segregation. These results suggest that esp-1 and esp-2 are located on chromosomes 10 and 9, respectively.