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PubMed2006

Alkaloid profiles, concentration, and pools in velvet lupine (Lupinus leucophyllus) over the growing season.

Lupinus leucophyllus is one of many lupine species known to contain toxic and/or teratogenic alkaloids that can cause congenital birth defects. The concentrations of total alkaloids and the individual major alkaloids were measured in three different years from different plant parts over the phenological development of the plant. All of the alkaloids were found in the different plant tissues throughout the growing season, although their levels varied in different tissues. Concentrations of total alkaloids and the individual alkaloids varied on an annual basis and in their distribution in the different tissues. Anagyrine levels were highest in the floral tissue, lupanine and unknown F accumulated to the greatest level in the vegetative tissue, and 5,6-dehydrolupanine accumulated to the highest level in the stem. These alkaloids appear to be in a metabolically active state with the teratogenic alkaloid anagyrine accumulating to its highest level in the developing seed. The latter is, thus, the phenological stage posing the greatest danger to grazing livestock.

Alkaloids↗
PubMed2005

Expression of MADS-box genes during the embryonic phase in Arabidopsis.

MADS domain factors play important roles as developmental regulators in plants. In Arabidopsis thaliana, MADS domain proteins have been shown to regulate various processes during the vegetative and reproductive phases. Relatively little is known, however, about family members expressed during the embryonic phase and their function. To determine which MADS-box genes are expressed during the embryonic phase in Arabidopsis, a family-wide survey involving gene-specific primers and RT-PCR was conducted. Transcripts corresponding to 64 (out of 109 total) family members could be detected in RNA samples isolated from embryonic culture tissue. Eight MADS-box genes that appear to be expressed at higher levels during the embryonic phase than in seedlings or in inflorescence apices were identified. The spatial pattern of expression in developing seeds was characterized for four MADS-box genes (FLOWERING LOCUS C, FLOWERING LOCUS M, AGAMOUS-LIKE 15, and AGAMOUS-LIKE 18) using reporter constructs encoding translational fusions to GUS. All four are expressed in cells throughout the endosperm and embryo. Finally, to test the hypothesis that AGAMOUS-LIKE15 (AGL15) and AGAMOUS-LIKE18 (AGL18) play essential roles during the embryonic phase, plants carrying T-DNA insertions that disrupt these genes were isolated. No embryo defects were observed in agl15 or agl18 single mutants or in agl15agl18 double mutants. These results indicate that multiple regulatory pathways that involve MADS domain factors are likely to operate in embryonic tissues, and that genetic and/or functional redundancy are likely to be as prevalent as in other phases of the life cycle.

AGAMOUS Protein, Arabidopsis↗
PubMed1991

Acyl-CoA elongase from a higher plant (Lunaria annua): metabolic intermediates of very-long-chain acyl-CoA products and substrate specificity.

A particulate fraction (15,000 x g pellet) from developing seeds of honesty (Lunaria annua) was found to synthesize very-long-chain acyl-CoA thioesters in a manner similar to mammalian systems, i.e., via condensation of an acyl-CoA with malonyl-CoA yielding beta-ketoacyl-CoA, which is reduced to beta-hydroxyacyl-CoA, the latter dehydrated to trans-2-enoyl-CoA that is finally reduced to very-long-chain acyl-CoA. Reduced pyridine nucleotides (NADH/NADPH) are required for the reduction steps. In the absence of reduced pyridine nucleotides only the condensation reaction occurs. The acyl-CoA elongase does not exhibit any pronounced specificity for any of the saturated (14:0 to 20:0) or (n - 9)cis-monounsaturated (14:1 to 22:1) acyl-CoA substrates, although both the saturated and monounsaturated acyl-CoA substrates having chain lengths of C18 and C20 are elongated somewhat faster.

Acyl-Carrier Protein S-Malonyltransferase↗
PubMed1992

Solubilization and partial purification of constituents of acyl-CoA elongase from Lunaria annua.

All the constituent enzymes of acyl-CoA elongase, i.e., beta-ketoacyl-CoA synthase, beta-ketoacyl-CoA reductase, beta-hydroxyacyl-CoA dehydrase and trans-2-enoyl-CoA reductase, have been solubilized from a 15,000 x g particulate fraction from developing seeds of honesty (Lunaria annua) using Triton X-100. All these activities were retained upon subsequent precipitation of the solubilized protein with polyethylene glycol and resuspension of the precipitate followed by ion exchange chromatography of the resulting protein on DEAE-cellulose. A 4.2-fold enrichment of the acyl-CoA elongase was thus obtained. Further chromatography of the DEAE fraction containing all the constituents of acyl-CoA elongase on Ultrogel yielded a major protein fraction exhibiting the activities of beta-ketoacyl-CoA synthase and beta-ketoacyl-CoA reductase only. Almost 30-fold purification of the beta-ketoacyl-CoA synthase was thus achieved. The beta-ketoacyl-CoA synthase was inhibited only at high concentrations of cerulenin, but at very low concentrations of iodoacetamide. Inhibition could be reduced by preincubation with thioesters, indicating that an enzyme thioester intermediate is involved in the condensation reaction of the acyl-CoA elongation.

3-Oxoacyl-(Acyl-Carrier-Protein) Synthase↗
PubMed1994

Cloning and sequence analysis of a cDNA encoding rice glutaredoxin.

A full-length cDNA clone (RASC8) encoding glutaredoxin (thioltransferase) was isolated from a cDNA library of an aleurone layer prepared from a developing seed of rice (Oryza sativa L.). RASC8, 568bp in length, contained an ATG codon and two possible polyadenylation signals, and encoded 112 amino acid residues. Cys-Pro-Phe-Cys, which is the active site and a highly conserved sequence among thioltransferases, was found in the deduced amino acid sequence. RASC8 was introduced into an expression vector pMALc2 and the translated product possessed thioltransferase activity.

Amino Acid Sequence↗
PubMed1995

Multiple isoforms of Pisum trypsin inhibitors result from modification of two primary gene products.

Characterization of Pisum (pea) seed trypsin inhibitors (TI) and their corresponding cDNAs indicates that the pea TI gene family contains two genes. The existence of multiple TI isoforms can be attributed to post-translational modifications of primary gene products. Post-translational processing at the C-terminus during the desiccation stage of seed development results in the appearance of TI isoforms with increased affinity for the target enzyme, trypsin.

Amino Acid Sequence↗
PubMed1995

NTR1 encodes a high affinity oligopeptide transporter in Arabidopsis.

Hterologous complementation of yeast mutants has enabled the isolation of genes encoding several families of amino acid transporters. Among them, NTR1 codes for a membrane protein with weak histidine transport activity. However, at the sequence level, NTR1 is related to rather non-specific oligopeptide transporters from a variety of species including Arabidopsis and to the Arabidopsis nitrate transporter CHL1. A yeast mutant deficient in oligopeptide transport was constructed allowing to show that NTR1 functions as a high affinity, low specificity peptide transporter. In siliques NTR1-expression is restricted to the embryo, implicating a role in the nourishment of the developing seed.

Amino Acid Sequence↗
PubMed1987

The impact of ozone on assimilate partitioning in plants: a review.

Numerous studies have shown that ozone (O(3)) reduces plant growth and changes assimilate partitioning. The pattern of such changes varies with species, but trends suggest a comprehensive model. O(3) generally reduces the amount of dry matter in the whole plant. In plants which have not flowered or set fruit, and at low O(3) levels, the remaining available assimilate is generally diverted to leaves and stems at the expense of roots and crowns. As the plant matures, flowers and develops seeds, these sinks receive a relatively high proportion of the available assimilate. O(3) may reduce the number of flowers or seeds, but the remaining seeds often have a total dry matter accumulation comparable to that in non-stressed plants. At higher O(3) levels, assimilate accumulation is greatly depressed, and partitioning changes are not as obvious. However, it is significant that the storage organs of plants-those organs which supply energy for new growth in perennial plants such as trees-are the organs most affected by O(3)-induced partitioning changes when O(3) concentrations are in the range commonly observed in polluted ambient air.

Journal Article↗
PubMed1987

Analyses of alpha/beta-type gliadin genes from diploid and hexaploid wheats.

The alpha/beta-gliadin genes isolated from both hexaploid wheat (cv. Yamhill) and the diploid A genome progenitor Triticum urartu had remarkably similar sequences and differ by only a few point mutations. Primer extension analysis indicated that the transcriptional start points for individual genes in the family cluster within a few nucleotides. Comparison of the promoter region of several alpha/beta-gliadin and B-hordein genes reveals two conserved regions at about -130 and -250 bp. DNA from the hexaploid cultivars, Cheyenne and Chinese Spring, and the diploid progenitors T. urartu and Aegilops squarrosa was analysed by Southern blotting. Restriction fragment lengths of the alpha/beta-gliadin genes varied only slightly between the various wheats, although the overall copy number varied significantly. A region between approx. -1700 and -700 bp upstream from the TATA box was highly repeated in all three wheat genomes. For the hexaploid-derived gene, over 1700 bp of sequence upstream from the TATA box was determined, revealing an additional open reading frame between approx. -1550 and -1250 bp relative to the gliadin TATA box. Northern blot analysis indicated that RNA homologous to this repeated sequence family was present only in developing seed and accumulated to a maximum at late stages of maturation.

Base Sequence↗
PubMed1991

Molecular characterization of the gene encoding a rice endosperm-specific ADPglucose pyrophosphorylase subunit and its developmental pattern of transcription.

The gene encoding a rice endosperm-specific ADPglucose pyrophosphorylase (AGPP) subunit was isolated and its structure determined by nucleotide (nt) sequencing. A comparison of the genomic and cDNA nt sequences revealed a complex gene structure with ten exons and nine introns spanning over 6 kb. The exons ranged in size from 293 to 99 nt and the introns were between 1435 and 84 nt in size, with the first intron being the largest. All of the intron splice sites, except intron-2, contained GT/AG borders and were similar to the published splice site consensus sequences. Intron-2 had CA/CC borders at the 5' and 3' ends, but sequences adjacent to the splice site borders shared homology to the splice site consensus sequence, suggesting that the overall splice region, rather than the specific GT/AG sequence, determines the splice site. Several sequence motifs which may play a role in the regulation of plant genes were evident upstream from the transcriptional start point. Analysis of the developmental pattern of expression revealed a maximum level of mRNA transcripts for AGPP at five days after flowering coincident with starch accumulation. This result suggests that starch biosynthesis is controlled at the transcriptional level during seed development.

Amino Acid Sequence↗
PubMed1993

Cloning and sequencing of 5' flanking sequence from the gene encoding 2S storage protein, from two Brassica species.

Using oligodeoxyribonucleotide primers and the polymerase chain reaction, we have cloned and sequenced about 1.2 kb of upstream sequences from two members of the 2S seed storage protein-encoding gene family from Brassica juncea and B. oleracea. The two sequences bear more than 90% homology and have characteristic seed-specific promoter motifs. The high degree of sequence conservation indicates that this napin-encoding gene family evolved earlier than the divergence of the three primary Brassica species and their amphidiploids, and the sequences have been conserved due to some metabolic constraints in seed development.

2S Albumins, Plant↗
PubMed2003

Identification and characterization of a sucrose transporter isolated from the developing cotyledons of soybean.

Reduced carbon produced in mature leaves is distributed throughout plants in the form of sucrose. Sucrose transporter proteins (SUT) play a crucial role in transporting sucrose. We isolated a cDNA encoding a sucrose transporter, GmSUT1, which is expressed in the developing cotyledons of soybean (Glycine max). [14C]sucrose uptake assays demonstrate that GmSUT1 has a K(m) of 5.6mM and a V(max) of 5.8 nmol sucrose min(-1)(mg cells)(-1), which are similar to those of the low-affinity-high-capacity sucrose transporter family. GmSUT1 protein accumulates gradually during cotyledon development, correlating with increasing sucrose levels in the maturing cotyledons. Collectively, these data suggest that GmSUT1 plays an active role in the movement of sucrose into the developing seeds.

Biological Transport↗
PubMed2001

Paternally inherited transgenes are down-regulated but retain low activity during early embryogenesis in Arabidopsis.

We investigated the timing of transgene activation after fertilisation in Arabidopsis following crosses and using two transgenic promoters (from the AtCYCB1 and AtLTP1 genes). Using both a transactivation system and direct transcriptional fusion to drive beta-glucuronidase reporter expression, reciprocal crosses showed a lack of expression of the paternal components. This is consistent with a lack of paternal genome activity previously reported during early seed development in Arabidopsis [Viella-Calzada et al. (2000) Nature 404, 91-94]. However, transactivation experiments of the BARNASE gene gave evidence that at least some paternal loci retain transcriptional activity, though at a low level, during early embryogenesis.

Arabidopsis↗
PubMed2001

Endoplasmic oleoyl-PC desaturase references the second double bond.

The regiospecificity for the gene product of fad2,(1) the microsomal oleoyl-PC desaturase from higher plants, differs from some previous suggestions. Rather than only referencing the carboxyl group (a Delta(12) desaturase) or the methyl terminus (an omega-6 desaturase), this desaturase locates the second double bond in its substrates by first referencing the existing double bond. This specificity was demonstrated for the oleoyl-PC desaturase cDNA from the developing seeds of peanut (Arachis hypogaea L) expressed in yeast (Saccharomyces cerevisae). The expressed enzyme was capable of desaturating monounsaturated fatty acyl groups in membrane lipids. Endogenous palmitoleate was desaturated to cis, cis 9,12 hexadecadienoate (9(Z)12(Z)C16:2), endogenous oleate to linoleate (9(Z)12(Z) octadecadienoate), and cis 10-nonadecenoate (provided as a supplement in the growth medium) to 10(Z)13(Z)C19:2. The rule, Delta(x+3) where x=9 is the double bond location in the substrate, best describes the consistent placement of the second double bond in the above monounsaturated substrates for the oleoyl-PC desaturase of higher plants.

Cytoplasm↗
PubMed1997

Purification and characterisation of a protein kinase from winged bean.

A soluble, cytoplasmic protein kinase was purified from the developing seeds of winged bean (Psophocarpus tetragonolobus) following conventional methods of protein purification including anion-exchange chromatography, gel-filtration and Blue Sepharose chromatography. The purified enzyme consists of a single polypeptide of M(r) 45,000 as determined by SDS-PAGE and gel-filtration chromatography on Sephacryl S-200. The pH optimum of the protein kinase activity was 7.0, while the optimum concentration of Mg2+ was 5 mM. The enzyme utilised casein as an exogenous phosphate acceptor. The conventional modulators of protein kinases, including the cyclic nucleotides, Ca2+ and calmodulin, did not stimulate the purified enzyme. Heparin and spermine, too, had no effect on its activity. Phosphoamino acid analysis revealed that the enzyme transferred the gamma-phosphate of ATP only to serine residues of casein. All these characteristics, taken together, classifies the purified protein kinase as a member of the casein kinase I group of enzymes.

Amino Acids↗
PubMed2000

Molecular characterization of a new arcelin-5 gene.

Arcelins are insecticidal proteins found in some wild accessions of the common bean, Phaseolus vulgaris. They are grouped in six allelic variants and arcelin-5 is the variant with the highest inhibitory effect on the development of Zabrotes subfasciatus larvae. Characterization of the protein and its genes resulted in the identification of three polypeptides and the isolation of two genes that encode the Arc5a and Arc5b polypeptides. Here we describe a new gene, Arc5-III. The protein it encodes has 81% amino acid identity with the derived amino acid sequences of Arc5-I and Arc5-II. The Arc5-III gene is highly expressed in developing seeds and at a much lower level in roots. Data obtained by a combination of two-dimensional gel electrophoresis, protein sequencing and MALDI-TOF mass spectrometry analysis support the conclusion that Arc5-III encodes a polypeptide present in Arc5c band. Using ion-exchange chromatography, three fractions containing arcelin-5 polypeptides were eluted by increasing the salt concentration. The three fractions contain various amounts of the three arc-5 polypeptides and inhibit the growth of Zabrotes subfasciatus larvae differentially, suggesting differences in insecticidal activity among the arcelin-5 isoforms.

Amino Acid Sequence↗
PubMed1999

Inhibition of reproductive growth of Arabidopsis in airtight vessels.

Airtight vessels have various advantages for space experiments. However, Arabidopsis thaliana plants scarcely produced seeds when grown in such vessels. The mechanism by which reproductive growth is inhibited in airtight vessels was studied. The length of the flower stalk was shorter when the plants were grown in airtight vessels. Thus, there was a possibility that the inhibition of reproductive growth was due to the inhibition of vegetative growth. However, even when the plants which has grown under non-airtight conditions and has reached to the flowering stage were transferred to airtight vessels, silique formation was inhibited, suggesting that the airtight environment directly influences reproductive growth. In airtight vessels, anther dehiscence was inhibited, which appears to be the cause of inhibition of silique formation and seed development. Reproductive growth recovered when silica gel was added to the vessels. These results suggest that in airtight vessels, high humidity causes a suppression of anther dehiscence, resulting in the inhibition of reproductive growth. Therefore, the control of humidity by ventilation should be taken into consideration in designing a growth chamber for space experiments.

Arabidopsis↗
PubMed2000

Seeds of conflict.

Recent studies have shown that the Arabidopsis MEDEA gene is imprinted, so that paternally and maternally inherited alleles are differentially expressed during seed development. Futhermore, a chromatin remodelling factor has been implicated as a novel trans-acting regulator of imprinting.

Arabidopsis↗