Tubulin from Mimosa pudica and its involvement in leaf movement

The sensitive plant Mimosa pudica is made insensitive by a brief treatment with colchicine. A high concentration of colchicine binding protein is present in the fresh actively moving leaves of M. pudica. This protein was partially characterized and compared with the animal brain tubulin. This colchicine binding activity is very low in the insensitive variety of Mimosa, namely Mimosa rubricaulis.     

Posidonia oceanica seedling root structure and development

The seedling root system of the seagrass Posidonia oceanica consists of a primary root and up to four adventitious roots. Under culture, germination and early growth began with the emergence of the primary root in the first week. Then the two adventitious root primordia originally present in the seed emerged at 3 and 5 weeks respectively, followed successively by further adventitious roots. Primary roots reached 17 mm at 4 weeks, but then their growth decreased markedly. In contrast the adventitious roots showed a pattern of continued elongation. Anatomical observations of both primary and adventitious roots revealed a multilayered hypodermis of thick-walled cells enclosing a wide cortex (99% of the root transverse area) and narrow stele. A well-distinguished endodermis was only observed in the primary roots, while differentiated xylem elements were found solely in the adventitious roots, but it is unclear to what degree differences between the two root types are due to different root maturity or to their role in water and nutrient uptake. Overall, the P. oceanica seedling root system is composed of multiple, rapidly formed roots which are strong yet flexible due to a large proportion of cortical tissue and further strengthened by a multilayered hypodermis, characteristics which could potentially facilitate initial anchorage and establishment.     

Cellular and chloroplast lipid composition of the leaves of Mimosa pudica

Cellular and chloroplast lipids of the leaves of Mimosa pudica have been analysed. Qualitatively the total lipid composition of this plant is similar to that reported for the photosynthetic tissues of other plants. Chloroplast lipids show some resemblance to those of algae. The cerebroside fraction of both leaves and chloroplasts contains a polyunsaturated fatty acid (20:4ω3) and a long chain sphingosine base whose R_f value coincides with that from ox brain cerebroside and not with that of phytosphingosine from spinach.     

Cytokinins in immature seeds of Dolichos lablab

Five cytokinins, trans-zeatin, 9-β-d-ribofuranosyl-trans-zeatin, 9-β-d-ribofuranosyl-cis-zeatin, 6-(trans-4-O-β-d-glucopyranosyl-3-methyl-2-butenylamino)purine and 6-(trans-4-O-β-d-glucopyranosyl-3-methyl-2-butenylamino)-9-β-d-ribofuranosylpurine were identified from immature seeds of Dolichos lablab.     

Pterocarpans of Neorautanenia edulis and N. Amboensis

The root bark of Neorantanenia edulis and N. amboensis yielded six new natural pterocarpanoids, the structures of which have been determined mainly by physical methods and by partial syntheses. They include edulane, edudiol, neoraucarpan, neorautanin, edulenol, and neoraucarpanol.     

Homoserine dehydrogenase in Pisum sativum and Ricinus communis

Homoserine dehydrogenase was extracted from Ricinus communis and Pisum sativum. The kinetic parameters of the forward and reverse reactions were determined. In the forward reaction only the enzyme from Ricinus is inhibited by threonine. The response to K⁺ is different for the enzyme from the two sources.     

Cyanogenesis in Acacia pachyphloia

The cyanogenic glycoside, proacacipetalin, is reported from Acacia pachyphloia (Acacia subgenus Acacia). This represents the first record of a glycoside with an aliphatic aglycone from a species of Acacia indigenous to Australia. This finding reinforces the taxonomic distinctions between subgenus Acacia and subgenus Phyllodineae.     

t-RNA-nucleotidyltransferase activity in Lupinus luteus seeds

t-RNA-nucleotidyltransferase activity was detected in Lupinus luteus seed.The enzyme was partly purified, and some of its properties are described.     

A mathematical model of phytoremediation for petroleum-contaminated soil: model development

We present a simple model for root length density that combines the generally accepted spatial (exponential decrease with depth) and temporal (sinusoidal) variability of root length. Parameters in this model for root length density can be determined from assumed or measured information regarding the annual biomass turnover, maximum standing biomass, and maximum depth of root penetration. The root length density model, coupled with information regarding the average root lifespan, gives specific root growth and senescence functions that are the forcing functions for the phytoremediation model. We present a screening level mathematical model for phytoremediation that accounts for the growth and senescence of roots in the system. This is an important factor for recalcitrant, immobile compounds found in weathered crude oil contaminated soils. The phytoremediation model is based on variable volume compartments that have individual first-order degradation rate constants; as the roots move through the soil, the soil cycles through the rhizosphere zone, decaying root zone and bulk soil zone. Thus, although the oil is immobile, as the roots penetrate through the soil the oil is brought into contact with the rhizosphere.     

De novo synthesis of acetylcholinesterase in roots of Pisum sativum

Pisum sativum seeds contain a conserved acetylcholinesterase (AChE) which is active during the early stages of germination. The enzyme activity soon disappears and reappears after 72 hr of germination. A protein devoid of catalytic ability, but exhibiting similar chromatographic and electrophoretic properties as the active AChE, could be detected after 24 hr of germination. The pattern of incorporation of labelled amino acids into AChE and the influence of cycloheximide revealed that the AChE found in the roots from 72 hr onwards was entirely new. During this period of growth, the AChE protein accounts for 4–10% of the total proteins in the root tissue.     

Role of root-mediated interactions in phytotoxic interference of Ageratum conyzoides with rice (Oryza sativa)

Ageratum conyzoides L. (billy goat weed; Asteraceae) is an annual invasive weed native of tropical America and has now naturalized worldwide, particularly in Southeast Asia. The present study investigated the nature and potential of root-mediated allelopathic interference of A. conyzoides against rice (Oryza sativa). Root and shoot length and biomass accumulation of rice were significantly reduced (by 18–30%) when grown in the rhizosphere soil of the weed indicating the release of putative allelochemicals from the weed into the soil. The growth of rice was also progressively reduced in the soil amended with increasing amounts of root residues (5, 10 and 20 g kg⁻¹ soil) of A. conyzoides. The addition of activated charcoal, an inert material with high affinity for organic biomolecules, partly ameliorated the negative effects of root residues amended in the soil. Further, there was no negative effect on the availability of soil nutrients in the root-amended soils. These were rather nutrient rich with greater electrical conductivity, and higher amount of organic matter, thus indicating no role in observed growth reduction. The reduction in allelopathic effects of root residue upon charcoal addition further indicated that putative phytotoxins released from the weed roots are water-soluble phenolic compounds. A significant amount of water-soluble phenolics were present in rhizosphere (∼6-times higher) and root-amended soils (∼5–10-fold higher) and their content was reduced (to ∼3.6–7.0-fold higher) when charcoal was added. The observed growth reduction in Ageratum rhizospheric or root-amended soils was concomitant with the amount of phenolic compounds. Upon HPLC analyses, these were identified as p-coumaric acid, gallic acid, ferulic acid, p-hydroxybenzoic acid and anisic acid. Under laboratory conditions, these phenolic acids reduced the root length and seedling weight of rice individually as well as in equimolar mixture, though no synergistic effect was noticed. The study concludes that root exudates and residues of A. conyzoides suppress the growth of rice by releasing phenolic allelochemicals into the soil rhizosphere and not through alteration of soil nutrients, and allelopathy plays a significant role in root-mediated negative interference of A. conyzoides.     

A comparative study of the flavonoids of Medicago radiata with other Medicago and related Trigonella species

The flavonoid glycosides of Medicago radiata as well as M. arabica, M. polymorpha, M. sativa, Trigonella coerulescens, T. foenum-graecum and T. spicata were studied in detail. Major glycosides identified were the 7-glucuronides of apigenin, luteolin, chrysoeriol and tricin, as well as lesser amounts of di- and triglucuronides of chrysoeriol and tricin. Also identified were the 3-robinobioside and 3,7-diglucoside of kaempferol, along with lesser amounts of quercetin-3,7-diglucoside, 4′,7-dihydroxyflavone, 3′,4′,7-trihydroxyflavone, formononetin and daidzein. Twelve other Medicago and Trigonella species were also studied for their flavonoid aglycones. The systematic position of M. radiata is discussed.     

Lysyl tRNAs of lupinus luteus seeds

Lysine accepting transfer RNA of lupin seeds and lupin embryo axes can be fractionated into at least 5 species by reversed-phase chromatography (RPC-5). One main and two minor isoacceptors were observed in wheat and barley embryos. Changes in isoaccepting species of tRNA^1ys were followed in cotyledons of germinating lupin seedlings. Ribosome binding studies revealed that one of the main lupin tRNA^1ys species recognizes the AAG codon, the second AAA and the third one AAA and AAG.     

Biological implications of flavonoid chemistry in Baptisia and Thermopsis

An analysis of flavonoid distributional data from detailed biochemical systematic investigations of Baptisia and Thermopsis species supports the contention that the two genera are closely related with Baptisia being the more advanced evolutionarily and exhibiting greater evolutionary vigor. B. megacarpa may represent an ancestral complex which gave rise to several major Baptisia lines. Enzymes involved in methoxylation and 4′-glucosylation of flavonoids in Thermopsis have higher substrate specificities than those involved in 7-glucosylation.     

Isoflavan phytoalexins from Anthyllis,lotus and Tetragonolobus

Two previously unreported phytoalexins, 7,4′dihydroxy-2′-methoxy- and 7,2′,4′-trihydroxyisoflavan, have been isolated from the fungus-inoculated leaves of Anthyllis vulneraria and 5 Tetragonolobus species. Examination of Lotus corniculatus revealed the co-occurrence of the latter with the known isoflavans, vestitol and sativan. Only 7,2′4′-trihydroxyisoflavan and vestitol were produced by the closely related L. uliginosus.     

Serological evidence confirming the assignment of phaseolus aureus and P. mungo to the genus vigna

Endopeptidase activity was detected in extracts of cotyledons of 11 species of Vigna and Phaseolus Antibodies against the purified protease isolated from the cotyledons of 5-day-old P.aureus seedlings inhibited the activity of that enzyme in crude extracts of cotyledons. A similar inhibition was obtained with P. mungo, P. adenanthus and 4 species of Vigna, while there was no inhibition of endopeptidase activity in extracts of cotyledons of 4 species of Phaseolus. Immunodiffusion tests proved that the protease of Vigna is distinct from that of Phaseolus. The evidence supports the reassignment of P. aureus and P. mungo to the genus Vigna and indicates that the names Vigna radiata and Vigna mungo are more appropriate than P. aureus and P. mungo for green gram and black gram respectively.     

2-Aminoimidazole in seeds of Mundulea sericea

An amine present as ca 0.9 % of the fr. wt of the seeds of the legume Mundulea sericea has been isolated and characterised as 2-aminoimidazole     

Nitropropanylglucopyranoses in Coronilla varia

The isolation and characterization of 6-(3-nitropropanyl)-d-glucopyranose from Coronilla varia is described and the concentration of the compound is determined by quantitative microisolation. Di- and tri-nitropropanylgluco-pyranoses are detected in C. varia and three Astragalus spp.     

Non-protein amino acids of Acacia species and their effect on the feeding of the acridids Anacridium melanorhodon and Locusta migratoria

The leaves of Acacia species have been found to contain homoarginine, pipecolic acid and 4-hydroxy-pipecolic acid. The nymphs of the tree locust Anacridium melanorhodon, which feed on the leaves of Acacia species, were not inhibited from feeding on palatable media containing concentrations of these amino acids equivalent to, or greater than, those found in the leaves. The graminivorous Locusta migratoria was more sensitive to these compounds, inhibitory effects being observed at concentrations comparable to those found in the leaves. The inhibitory effects of mixtures of homoarginine and pipecolic acid were additive in A. melanorhodon but not in L. migratoria. Three of the non-protein amino acids found in the seeds of Acacia species, 2,3-diaminopropionic acid, 2-amino-3-acetylaminopropionic acid and 2-amino-3-oxalylaminopropionic acid, were more effective inhibitors of feeding in Anacridium than were the leaf amino acids.     

The allantoinase of Lathyrus sativus

The presence of a stable allantoinase in Lathyrus sativas and its de novo synthesis at a maximal rate in the first 48 hr of germination have been demonstrated. The plumule and radicle together exhibited highest enzyme activity. L. sativas allantoinase has been purified nearly 35-fold. The purified enzyme was optically active around pH 7.5, did not require any metal ion for activity and exhibited a K_m of 2·56 mM for (±)-allantoin, and an activation energy of 5·6 kcal/mol. Unlike other plant allantoinases, the L. sativus enzyme is highly specific for (±)-allantoin and is shown to be a sulfhydryl enzyme which apparently exists in a stable form in vivo obviating the need for added sulfhydryl compounds for maximal activity.