Novel nor-harmal alkaloid from Adhatoda vasica

A novel alkaloid and a galactoside isolated from the roots of Adhatoda vasica have been characterized as 9-acetamido-3,4-dihydropyrido-(3,4-b)-indole and O-ethyl-α-D-galactoside respectively by chemical and spectroscopic methods. In addition sitosterol β-D-glucoside, D-galactose and deoxyvasicinone have also been isolated from the roots of this plant.     

A furanoeremophilane from Vitex negundo

Acetyl oleanolic acid, sitosterol and a new furanoeremophilane characterized as 3-formyl-4,5-dimethyl-8-oxo-5H-6,7-dihydronaphtho(2,3-b)furan have been isolated from the roots of Vitex negundo.     

The Histopathological Reactions of Vigna sinensis to Separate and Concomitant Parasitism by Meloidogyne javanica and Rotylenchulus reniformis

Cellular alterations in cowpea roots and nodules induced by single and concomitant Meloidogyne javanica and Rotylenchulus reniformis were investigated. M. javanica induced giant cells inside the vascular bundles of roots and nodules, and syncytia in cortical tissue of the nodules. In contrast, R. reniformis stimulated hypertrophy of pericycle and endodermal cells of the roots and nodules. Syncytia induced in the roots involved a sheet of pericycle cells and an endodermal cell. Cortical ceils of nodules also responded to R. reniformis infection, initiating wall gaps that led to syncytial formation. Coincidence of giant cells or syncytla of both nematodes was observed either in one vascular bundle or in separate ones. The histopathology of roots and nitrogen nodules infected by the two species remained unique even when they were feeding in close proximity. R. reniformis induced characteristic syncytia and M. javanica induced giant cells.     

Furanocoumarins from Heracleum canescens

The ethanolic extract of the fresh roots of Heracleum canescens has afforded, besides sitosterol, osthol, methyl 3,4,5-trimethoxybenzoate and 11 furanocoumarins.     

Aliphatic hydroxyketones and diosgenin from Costus speciosus roots

Two new compounds, B and C, isolated from the roots of Costus speciosus have been characterized as 24-hydroxyhentriacontan-27-one and 24-hydroxytriacontan-26-one by spectral data and chemical studies. Methyl triacontanoate, diosgenin and sitosterol have also been isolated and identified.     

Steroids,chromone and coumarins from angelica officinalis

From the ethyl acetate extract of the fresh roots of Angelica officinalis var. himaliaca, besides sitosterol, pregnenolone, peucenin-7-methyl ether, osthol and 18 furanocoumarins have been characterized by spectroscopic methods, including ¹³C NMR, and some chemical transformations.     

Alfalfa Root Nodule Carbon Dioxide Fixation : III. Immunological Studies of Nodule Phosphoenolpyruvate Carboxylase

Antiserum was prepared in rabbits against purified alfalfa (Medicago sativa L.) nodule phosphoenolpyruvate carboxylase (PEPC). Immunotitration assays revealed that the antiserum recognized the enzyme from alfalfa nodules, uninoculated alfalfa roots, and from soybean nodules. Tandem-crossed immunoelectrophoresis showed that the PEPC protein from alfalfa roots and nodules was immunologically indistinguishable. The 101 kilodalton polypeptide subunit of alfalfa nodule PEPC was identified on Western blots. The PEPC polypeptide was detected in low quantities in young alfalfa roots and nodules but was present at increased levels in mature nodules. Senescent nodules appeared to contain a reduced amount of the PEPC polypeptide. PEPC was also detected by western blot in some plant- and bacterially-conditioned ineffective alfalfa nodules but was not detected in bacteroids isolated from effective nodules. Alfalfa nodule PEPC is constitutively expressed in low levels in roots. In nodules, expression of PEPC polypeptide increases several-fold, resulting in increased PEPC activity. Antiserum prepared against the C₄ PEPC from maize leaves recognized the PEPC enzyme in all legume nodules and roots tested, while the antiserum prepared against alfalfa nodule PEPC also recognized the leaf PEPC of several C₄ plant species. Neither antiserum reacted strongly with any C₃ leaf proteins. The molecular weight of the PEPC polypeptide from C₄ leaves and legume nodules appears to be similar.     

Nodule distribution on the roots of actinorhizal Discaria trinervis (Rhamnaceae) growing in pots

Roots of actinorhizal plants can develop nitrogen-fixing nodules with actinomycetic bacteria of the genus Frankia. We aimed to know if unrestricted growth of roots in pots could influence the pattern of nodule development that we had previously observed for Discaria trinervis growing in pouches. Growth pouches, although being a space saving device convenient for the analysis of nodule development, do restrict root growth. Thus, the pattern of root nodule development was analysed in actinorhizal D. trinervis growing in pots with inert substrates. Inoculation of axenic seedlings growing in perlite resulted in clustering of nodules in a defined region of the taproot and upper lateral roots. When surface sterilized seeds were sown in pots containing vermiculite that had been previously inoculated with Frankia cells, nodules were again concentrated in defined portions of the main and lateral roots. Potted plants developed comparable numbers of nodules with respect to plants grown in pouches. However, a significant proportion of nodules appeared in lateral roots. As it was first inferred from field grown plants, these results confirm that D. trinervis plants growing in pots display the same autoregulatory mechanism for nodule formation that was previously observed in growth pouches.     

Nodule Activity and Allocation of Photosynthate of Soybean during Recovery from Water Stress

Nodulated soybean plants (Glycine max [L.] Merr. cv Ransom) in a growth-chamber study were subjected to a leaf water potential (Ψ_w) of −2.0 megapascal during vegetative growth. Changes in nonstructural carbohydrate contents of leaves, stems, roots, and nodules, allocation of dry matter among plant parts, in situ specific nodule activity, and in situ canopy apparent photosynthetic rate were measured in stressed and nonstressed plants during a 7-day period following rewatering. Leaf and nodule Ψ_w also were determined. At the time of maximum stress, concentration of nonstructural carbohydrates had declined in leaves of stressed, relative to nonstressed, plants, and the concentration of nonstructural carbohydrates had increased in stems, roots, and nodules. Sucrose concentrations in roots and nodules of stressed plants were 1.5 and 3 times greater, respectively, than those of nonstressed plants. Within 12 hours after rewatering, leaf and nodule Ψ_w of stressed plants had returned to values of nonstressed plants. Canopy apparent photosynthesis and specific nodule activity of stressed plants recovered to levels for nonstressed plants within 2 days after rewatering. The elevated sucrose concentrations in roots and nodules of stressed plants also declined rapidly upon rehydration. The increase in sucrose concentration in nodules, as well as the increase of carbohydrates in roots and stems, during water stress and the rapid disappearance upon rewatering indicates that inhibition of carbohydrate utilization within the nodule may be associated with loss of nodule activity. Availability of carbohydrates within the nodules and from photosynthetic activity following rehydration of nodules may mediate the rate of recovery of N₂-fixation activity.     

Responses of Rj(1) and rj(1) Soybean Isolines to Inoculation with Bradyrhizobium japonicum

We evaluated the symbiotic phenotypes of nodulation-restrictive and normal soybean isolines by inoculating Clark (genotypically Rj₁Rj₁) and mutant Clark-rj₁ (genotypically rj₁rj₁) seedlings in plastic growth pouches. Nodules first appeared on Clark seedlings inoculated with Bradyrhizobium japonicum USDA 94 after 6 days. The mean number of nodules per plant was 13.9 ± 0.8 after 24 days. In contrast, Clark-rj₁ seedlings first nodulated at 12 days, and the mean number of nodules per plant was only 1.7 ± 0.3 at 24 days. Segments from infectible zones of primary roots, i.e. near the position occupied by the root tip at the time of inoculation, were sectioned serially. Clark roots contained cortical cell divisions and a few infection threads in question mark-shaped root hairs by 2 days after inoculation. Typical nodules developed soon thereafter. Analogous serially sectioned segments from Clark-rj₁ roots lacked these responses. This prompted us to section nodules and adjacent tissues from other parts of Clark and Clark-rj₁ roots. Clark roots contained cortical cell divisions, many associated with infected root hairs. Cortical cell divisions occasionally were present in Clark-rj₁, and a few infection threads were visible in surface cells. The presence of infection threads within Clark-rj₁ nodules was confirmed by transmission electron microscopy. Thus, although B. japonicum USDA 94 fails to elicit the wild-type spectrum of responses in the infectible zones of primary roots, it can infect Clark-rj₁ via infection threads.     

Sterol and triterpenoid glycosides from the roots of Patrinia scabiosaefolia

From the roots of Patrinia scabiosaefolia, oleanolic acid, hederagenin, 3-O-α-l-arabinopyranosyl-oleanolic acid, 3-O-α-l-arabinopyranosyl-hederagenin, 2′-O-acetyl-3-O-α-l-arabinopyranosyl-hederagenin and a mixture of sitosterol and campesterol-d-glucosides were isolated.     

Isolation of a natural sterol and an aliphatic acid from Vernonia cinerea

From the roots of Vernonia cinerea a new natural sterol and a new aliphatic acid characterized as stigmast-5,17(20)-dien-3β-ol and 26-methylheptacosanoic acid, respectively, have been isolated together with stigmasterol and sitosterol.     

The extraction and quantification of ergosterol from ectomycorrhizal fungi and roots

Recently, ergosterol analysis has been used to quantify viable fungal biomass in resynthesized ectomycorrhizae. An objective of our study was to quantify ergosterol in a range of ectomycorrhizal isolates under differing growth conditions. In addition, we tested the applicability of the method on field-collected roots of ectomycorrhizal and vesicular-arbuscular (VA) mycorrhizal plants. Quantification of sitosterol as a biomass indicator of plant roots was also undertaken. Ergosterol was not detected in roots of uninoculated Betula populifolia seedlings, and sitosterol was not detected in an ectomycorrhizal fungal isolate but was present in birch roots. Ergosterol was produced in all isolates examined, which represented the major orders of ectomycorrhizal fungi. The range of values obtained, from 3 to nearly 18 g ergosterol mg^-1 dry mass, agrees well with reported values for other mycorrhizal and decomposer fungi. Hyphal ergosterol was the same during growth on phytic acid and KH₂PO₄. Reduction of growth temperature from 25° C to 15° C had little effect on ergosterol content of cultures harvested at similar growth stages. Ergosterol and sitosterol were detected in field-collected ectomycorrhizae of B. populifolia and Pinus sylvestris and VA mycorrhizae of Acer rubrum and Plantago major. Both ergosterol content and ergosterol to sitosterol ratios were significantly lower in VA mycorrhizae than ectomycorrhizae. Calculations of viable fungal biomass associated with field-collected roots were in agreement with those reported by others using the method on resynthesized ectomycorrhizae. Estimates of total mass could be obtained for field-collected B. populifolia roots by a simultaneously using ergosterol to estimate fungal biomass and sitosterol to estimate root mass. Some potential applications and limitations of sterol quantification in studies of mycorrhizal physiology and ecology are discussed.     

7-Oxo-, 7α-hydroxy- and 7β-hydroxysterols from Euphorbia fischeriana

7-Oxo, 7α-hydroxy- and 7β-hydroxysterols (campesterol, stigmasterol and sitosterol derivatives) were isolated from the roots of Euphorbia fischeriana, a drug used for its antitumour properties in traditional Chinese medicine. Some of these steroids show antitumour activity and might be related to the presumed activity of the drug.     

Sucrose synthase and enolase expression in actinorhizal nodules ofAlnus glutinosa: comparison with legume nodules

Two different types of nitrogen-fixing root nodules are known — actinorhizal nodules induced byFrankia and legume nodules induced by rhizobia. While legume nodules show a stem-like structure with peripheral vascular bundles, actinorhizal nodule lobes resemble modified lateral roots with a central vascular bundle. To compare carbon metabolism in legume and actinorhizal nodules, sucrose synthase and enolase cDNA clones were isolated from a cDNA library, obtained from actinorhizal nodules ofAlnus glutinosa. The expression of the corresponding genes was markedly enhanced in nodules compared to roots. In situ hybridization showed that, in nodules, both sucrose synthase and enolase were expressed at high levels in the infected cortical cells as well as in the pericycle of the central vascular bundle of a nodule lobe. Legume sucrose synthase expression was studied in indeterminate nodules from pea and determinate nodules fromPhaseolus vulgaris by usingin situ hybridization.     

Nitrate-dependent N₂O emission from intact soybean nodules via denitrification by Bradyrhizobium japonicum bacteroids

In the presence of nitrate, N₂O emission increased markedly from soybean roots inoculated with nosZ mutant of Bradyrhizobium japonicum, but not from soybean roots inoculated with a napA nosZ double mutant, indicating that B. japonicum bacteroids in soybean nodules are able to convert the exogenously supplied nitrate into N₂O via a denitrification pathway.     

Control of root architecture and nodulation by the LATD/NIP transporter

The Medicago truncatula LATD/NIP gene is essential for the development of lateral and primary root and nitrogen-fixing nodule meristems as well as for rhizobial invasion of nodules. LATD/NIP encodes a member of the NRT1(PTR1) nitrate and di-and tri-peptide transporter family, suggesting that its function is to transport one of these or another compound(s). Because latd/nip mutants can have their lateral and primary root defects rescued by ABA, ABA is a potential substrate for transport. LATD/NIP expression in the root meristem was demonstrated to be regulated by auxin, cytokinin and abscisic acid, but not by nitrate. LATD/NIP''s potential function and its role in coordinating root architecture and nodule formation are discussed.Key words: nodule development, lateral root development, root architecture, symbiotic nitrogen fixation, Medicago truncatula, NRT1(PTR) gene familyUnlike most other plants, legumes form two kinds of lateral root organs: lateral roots and nitrogen-fixing root nodules that form in conjunction with compatible symbiotic rhizobium bacteria. Although the morphology and function of these two root organs is distinct, both require the function of the LATD/NIP gene, indicating shared genetic components for these two developmental processes and providing support for a model in which legume nodules evolved from a lateral root blueprint. Both lateral roots and nodules initiate in previously differentiated root cells in response to environmental and developmental cues mediated by hormones. Interestingly, regulation of nodules and lateral roots by hormones is often opposite, allowing formation of one organ or another depending on the conditions.     

Localized Changes in Flavonoid Biosynthesis in Roots of Lotus pedunculatus after Infection by Rhizobium loti

Two-dimensional paper chromatography in four solvent systems, high-sensitivity spray reagents, and UV absorption spectroscopy were used to separate and characterize flavonoids and isoflavonoids in roots and root nodules of 20-d-old Lotus pedunculatus Cav. Seedlings were grown either under sterile conditions or after inoculation with Fix⁺ or Fix⁻ strains of Rhizobium loti. Flavonoids rather than isoflavonoids predominated in all tissues. Flavonoid profiles in sterile and denodulated root tissues were remarkably similar, both qualitatively and quantitatively. At least 14 partially purified flavonoid aglycones and conjugates were found in root extracts; denodulated root tissues contained no compounds that were not also present in sterile roots. Fix⁺ rhizobia were responsible for major postinfection shifts in plant flavonoid biosynthesis at the sites of nodule morphogenesis. Polymeric flavolans were absent from Fix⁺ nodules but present in all root tissues and in Fix⁻ nodules. Catechin was detected only in Fix⁺ nodules.