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Plants are sources of diverse classes of natural products, some of which have biological activity such as phytotoxins, nematocidal, antimicrobial, phytoalexins, provide nutrition to soil microbes and are allelopathic. In fact the chemical compounds that are released from plant organs (i.e. leaves, stem, roots, flowers and seeds), have an effect on the environment and are known as allelochemicals. These allelochemicals comprises of low molecular weight compounds (such as sugars, inorganic ions, vitamins, nucleotides, amino acids and phenolics), as well as high molecular weight substances (polysaccharides and enzymes and other proteins). Furthermore, the allelochemicals from the source plant can enter the environment through leaching, volatilisation, root exudation and seed-coat exudation in order to protect themselves from the threat around them. The aim of this study is to give a picture of different classes of allelochemicals and their properties. Besides, this review will provide an insight regarding the utilisation of the compounds of interest as a growth regulator, antimicrobial, nematicidal, and/or natural herbicide. Certainly, this paper will help in promoting green agriculture and controlling pollution caused by synthetic chemicals.
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© by PSP Volume 28 No. 2A/2019 pages 1040-1049 Fresenius Environmental Bulletin
Amjad Iqbal1,2,*, Farooq Shah2, Muhammad Hamayun3, Zafar Hayat Khan2, Badshah Islam2,
Gauhar Rehman4, Zia Ullah Khan2, Sadiq Shah2, Anwar Hussain3, Yousaf Jamal5
1Institute of Molecular Plant Sciences, The University of Edinburgh, Mayfield road, Edinburgh, EH9 3JH, United Kingdom.
2Department of Agriculture, Abdul Wali Khan University Mardan-Pakistan.
3 Department of Botany, Abdul Wali Khan University Mardan-Pakistan.
4 Department of Zoology, Abdul Wali Khan University Mardan-Pakistan.
5Department of Agriculture, University of Swabi-Pakistan.
Plants are sources of diverse classes of natural
products, some of which have biological activity
such as phytotoxins, nematocidal, antimicrobial,
phytoalexins, provide nutrition to soil microbes and
are allelopathic. In fact the chemical compounds
that are released from plant organs (i.e. leaves,
stem, roots, flowers and seeds), have an effect on
the environment and are known as allelochemicals.
These allelochemicals comprises of low molecular
weight compounds (such as sugars, inorganic ions,
vitamins, nucleotides, amino acids and phenolics),
as well as high molecular weight substances
(polysaccharides and enzymes and other proteins).
Furthermore, the allelochemicals from the source
plant can enter the environment through leaching,
volatilisation, root exudation and seed-coat
exudation in order to protect themselves from the
threat around them. The aim of this study is to give
a picture of different classes of allelochemicals and
their properties. Besides, this review will provide
an insight regarding the utilisation of the
compounds of interest as a growth regulator,
antimicrobial, nematicidal, and/or natural herbicide.
Certainly, this paper will help in promoting green
agriculture and controlling pollution caused by
synthetic chemicals.
Allelochemicals, Bioactive compounds, Bio-herbicides,
Nematocides, Phytotoxic, Fungicides
Plants can serve as a reserviour for diverse
classes of natural products,some of them have
biological activity, including nematocidal,
phytotoxic, antimicrobial, phytoalexins, signalling
[1-8], and provide nutrition to soil microbes [9-14].
The exudates from various plant organs contain low
molecular weight compounds (such as sugars,
inorganic ions, vitamins, nucleotides, amino acids
and phenolics) [6, 15-20], higher molecular weight
substances (polysaccharides and enzymes and other
proteins) and root border cells (RBCs) [4, 21-25].
Many of the compounds that exude from
various plant organs e.g. seeds, stems, leaves,
flowers and roots have a positive or negative effect
on environment [26-31]. For example, root exudate
was observed to contribute to the complex set of
chemical, physical and biological interactions in the
rhizosphere, including rootroot, rootnematode,
and rootmicrobe interactions [12, 32-36].
Plant root vs plant root, plant root vs nematode
and plant root vs microbial interactions can either
be positive or negative [37]. For example when root
exudate provide nutrition to the beneficial
microorganisms then the interactions are regarded
as positive while root exudate containing
nematocides or antimicrobial agent against
nematodes or microorganism the interactions are
said to be negative. In short, plant exudates consist
of complex mixtures of large and small molecules,
which might have an effect on neighbouring
Allelopathy. Allelopathy, which means the
effect of one plant species on the germination,
growth and development of other plant species, has
been known for over 1000 years. The allelopathic
effect of chickpea (Cicer arietinum) and barley
(Hordeum vulgare) on weeds and other plant
species were known even before 300 BC (Rice,
The word allelopathy was first introduced by
Molish in 1937 and is derived from Greek words
allelon ‘of each other’ and pathos ‘to suffer’, which
means the injurious effect of one species upon the
other species. In 1996 allelopathy was defined by
the International Allelopathy Society as “Any
process involving secondary metabolites produced
by plants, micro-organisms, viruses, and fungi that
influence the growth and development of
© by PSP Volume 28 No. 2A/2019 pages 1040-1049 Fresenius Environmental Bulletin
agricultural and biological systems (excluding
animals)” [38].
The secondary metabolites that are released by
plant organs such as roots, rhizomes, leaves, stems
and seeds into the environment and that affect other
plants in the rhizosphere are known as
allelochemicals (Fig. 1). These allelochemicals
might enter the environment through different
routes like leaching, volatilisation, root exudation,
seed-coat exudation after imbibition and
decomposition of different parts of the plant [26,
39-42]. When susceptible plant species are exposed
to allelochemicals, germination might be inhibited
and if they germinate they might show abnormal
growth and development. The most visible effects
observed are retarded germination, short or no
roots, lack of root hairs, abnormally long or short
shoots, swollen seeds and low reproductive ability
Various routes through which allelopathic
compounds interact with the environment.
Leaf extracts of both Eucalyptus camadulensis
and Juglans regia and seed extracts of Onobrychis
sativa contain allelopatheic compounds that can
inhibit the germination and seedling growth of
other plant species [14]. Some of the putative
allelochemicals (cis-xanthoxin and trans-xanthoxin)
from the leaf extracts of Pueraria thumbergiana
caused growth inhibition of L. sativum roots [44].
Extracts from the flowers of Chrysanthemum
cinerariefolium contain a biologically active
compound known as pyrethrin with herbicidal
effect [28]. Pisatin 1 is also a good example of an
allelopathic compound found in the extracts of pea
stem residues that effected the growth of L. sativum
Allelopathy vs competition. Differentiation
between allelopathy and competitionis very
important. In allelopathy a plant exudes into the
environment a compound or compounds [46, 47],
which affect the rhizosphere, while in competition a
plant has the ability to remove or reduce the
existing reserves (e.g. water and nutrients in the
soil, and light from sun) in the environment [48].
In past an attempt was made to differentiate
between allelopathy and competition [49]. A boreal
dwarf shrub Empetrum hermaphroditum was used
as donor species and Scots pine (Pinus sylvestris) as
receiver species. The seedlings of P. sylvestris were
grown for 27 months among E. hermaphroditum.
The different treatments used were: (a) P. sylvestris
were grown in PVC(polyvinyl chloride) transparent
plastic tubes (root-exclusion tubes), which
minimized the effect of resource competition by
roots, (b) activated carbon was used to adsorb the
allelochemicals that were released by the E.
hermaphroditum, (c) PVC tubes and activated
carbon was used to minimize the effect of both
resource competition and allelopathic effect of E.
hermaphroditum, and (d) seeds of P. sylvestris were
grown in untreated E. hermaphroditum vegetation
in order to examine the consequences of both
allelopathy and resource competition on the growth
inhibition and weight gain of the P. sylvestris
After 27 months of plant growth, shoot weight
and length of the P. sylvestris seedlings was studied
[49]. The seedlings from treatments a, b, and d had
shorter shoots and lower dry weight than those from
c. The effect of root competition was higher than
that of toxic compounds because seedlings from
root-exclusion tubes with no activated carbon (a)
were affected less than seedlings from the treatment
with activated carbon to adsorb the allelochemicals
but without reducing the competition (b). The
results of the experiment led to conclude that both
competition (below-ground) and allelopathy has
caused inhibition of shoot elongation and failure to
gain weight in P. sylvestris seedlings.
Wardle et al. [50] have also selected six
species of grass: Dactylis glomerata (cocksfoot),
Phalaris aquatica (phalaris), Bromus wildenowii
(prairie grass), Lolium perenne (perennial ryegrass),
Festuca arundinacea (tall fescue) and Holcus
lanatus (Yorkshire fog) as donor species and
Carduus nutans or nodding thistle (a major weed in
many temperate regions) as an acceptor species.
The collected root and shoot leachates from the
donor species were analysed for their nutrient
content (i.e. ammonium, phosphate and nitrate) and
were tested for their effect on the germination and
growth of C. nutans. The collected root leachates
from the six grass species had no significant effect
on the germination and growth of C. nutans.
However, both hypocotyl and root growth of the C.
nutans were significantly reduced by the shoot
leachates of P. aquatica, L. perenne, H. lanata and
F. arundiancea. As the nutrient concentration in
both root and shoot leachates of the six species was
not significantly different, it was concluded that the
differential effect was purely due to allelochemicals
present in the shoots of the four donor species and
© by PSP Volume 28 No. 2A/2019 pages 1040-1049 Fresenius Environmental Bulletin
not to competition.
Factors interacting with allelochemicals in
soil. Many factors interact with allelochemicals
such as soil pH, organic matter content, nutrient and
moisture content [51]. An allelochemical can either
retain or lose its effectiveness at a given
concentration according to the availability or non-
availability of more readily available carbon
sources to soil microbes. Soil microbes may
preferentially metabolize readily available carbon
sources other than organic allelopathic compounds
and thus leave the soil relatively enriched in
allelochemicals, which are available for the uptake
by plant roots [52-54]. The concentration of
released allelochemicals in the rhizosphere also
depends upon the age of the allelopathic plant. A
young plant releases more allelochemicals into
surroundings, which might help it in establishing
themself among well-established plants [55].
The transformation of allelochemicals in the
soil can result in more or less toxic compounds.
Some allelochemicals are labile while others such
as some alkaloids resist changes because of their
anti-microbial activity (Wink et al. 1998). Some of
the transformed products from allelochemicals
become more potent than the original compound:
for example the hydroxamic acids DIMBOA (2,4-
dihydroxy-7-methoxy-1,4-benzoxazin-3-one) and
MBOA (6-methoxy-benzoxazolin-2-one) from
maize and wheat become more active when
transformed into the corresponding derivatives,
DIBOA (2,4-dihydroxyl-1,4-benzoxazin-3-one) and
BOA (2-benzoxazolinone) by removal of
formaldehyde from the parent molecule [56].
Allelopathy also has a close relationship with
plant stresses; because most stressed plants have the
ability to release allelochemicals into the
environment to a greater concentration than normal.
By doing so they are targeting the stress-producing
competitor plants, nematodes or microorganisms
with allelochemicals. Measuring the effects of
allelochemicals and the concentration released
might aid to establish association between
allelopathy and stress [57]. Other factors that are
responsible for the release or effectiveness of
allelochemicals are soil nutrient and water
availability, light, pesticide treatment and diseases
[58]. Actually allelopathy is a complex
phenomenon which can be affected by various
factors including soil pH, moisture, organic matter,
and micro-organisms), age (young vs. old plant) of
donor and receiver plants and climatic factors
(temperature and rain) (Fig. 2). The released
allelochemicals adsorbed on soil solids and further
metabolized biologically (micro-organisms) and
chemically (oxidation or reduction) with time.
Allelochemicals from trees. The study of
compounds that are released by some plants to
affect the environment is of great importance to
understand the mechanism of ecological interaction
[59]. In most studies allelopathy played essential
role in forests development by effecting the
composition of the flora. Juglone is a known
allelopathic compound release by walnut (Juglans
nigra), that can negatively effect the growth and
development of other plants species [60]. Under
natural conditions juglone enters the soil through
various process including root exudation, litter
decay and rain through fall. Since root exudation is
a continuous process, it is assumed that juglone is
Factors affecting behaviour and the phytotoxic activity of allelochemicals in soil
Modified from Kobayashi [51].
© by PSP Volume 28 No. 2A/2019 pages 1040-1049 Fresenius Environmental Bulletin
continuously added to the soil, affecting the
neighboring plants [61]. Although Davis [60]
observed that plants grown in the vicinity of black
walnut died because of the presence of juglone, the
physiological action of juglone was not well
understood until the study conducted by [62]. This
study showed that juglone at a concentration of 10
μM inhibited the growth of duckweed (Lemna
minor) by decreasing the chlorophyll content and
net photosynthesis rate. The results were further
confirmed by an experiment in which leaf discs of
soya bean (Glycine max) were placed in 10 μM
juglone: the rate of photosynthesis was reduced.
In North America both maize (Zea mays) and
soya bean (G. max) are often planted with black
walnut but had not been studied for the adverse
effect of black walnut until [61]. They studied the
effect of juglone on these crops in detail. Seedlings
of both species (maize and soya) when exposed to
juglone had stunted root and shoot growth, low leaf
photosynthesis, and leaf and root respiration of both
species, but soya was found more sensitive than
maize [61].
Another good example of an allelopathic tree
is tree of heaven (Ailanthus altissima), a native
Chinese tree that was introduced in Europe around
the 18th century. This tree is now widely distributed
in the world and can thrive among a wide variety of
floras, which might be due to its ability to produce
several classes of allelochmicals [63]. The first
investigation on the phytotoxic activity of A.
altissima extract was that of Mergen [64]; it was
confirmed by Voigt and Mergen [65]. In both
studies the authors found that aqueous extracts of
A. altissima were toxic to nearby plants.
A bioassay experiment to study the
allelopathic effect of A. altissima extracts on
germination and subsequent radicle growth was
done by De Feo et al. [59]. The surface-sterilized
seeds of radish (Raphanus sativus), garden cress
(Lepidium sativum) and purslane (Portulaca
oleracea) were incubated in Petri dishes containing
filter paper, impregnated with aqueous extract from
A. altissima or distilled water as a control. The A.
altissima extract inhibited the root growth of radish,
garden cress and purslane by 100, 80 and 72%
respectively. The active compounds were isolated
from the crude extract and identified as terpenoids:
ailanthone, ailanthinone, chaparrine and ailanthinol
B. [59] suggested that the active principle from A.
altissima could be used as a possible natural
herbicide. Phytochemical studies of A. altissima
revealed triterpenoids [66], lipids and fatty acids
[67], phenolics [68] and volatile compounds [69]
are the main allelopathic compounds.
Allelopathic crop species. Wheat. Wheat
(Triticum aestivum), one of the essential staple
food-crops, has been studied extensively for its
allelopathic potential. Aqueous extracts of wheat
residue (dried leaves and stem) and seedlings are
autotoxic [70] and showed an allelopathic effect
against weeds [71]. The inhibitory effect of an
aqueous extract from wheat straw on the
germination and growth of rye grass (Lolium
rigidum) increased interest in separating and
identifying the active compounds [71]. The
phytotoxic compounds identified in extracts were
mainly phenolic acids and benzoxazinone [72].
Rice. Various staple crops have been screened
for their weed suppressive field performances
and/or laboratory allelopathic potential, with rice
being the most thoroughly studied staple crop spe-
cies [73]. Various classes of compounds have been
identified as allelochemicals from rice exudates
including phenolics, fatty acids, benzoxazinoids
and terpenoids. Compounds putatively responsible
for growth inhibition isolated from rice root exu-
dates are the diterpenoid, momilactone B (3,20-
olide); a flavone (5,7,4′-trihydroxy-3′,5′-
dimethoxyflavone); and a cyclohexenone (3-
isopropyl-5-acetoxycyclohex-2-enone) [73]. Gener-
ally, different classes of allelochemicals are distrib-
uted among different tissues of rice seedling with
root tissues containing large quantities of phenolic
acids while momilactone B, the flavone and the
cyclohexenone are abundant in both root and shoot
tissues [74].
Barley. Barley (Hordeum vulgare) is a
smother crop that possesses allelopathic potential to
inhibit weed growth [75]. The secondary
metabolites (alkaloids: gramine and hordenine) that
are released by the barley root are responsible for
the inhibition of Sinapis alba, a weed plant. The
alkaloids from barley root exudates were separated
and quantified by HLPC. Hordenine was a major
component of barley root exudates with a
production rate of 2 μg/plant/day in hydroponic
solution. Purified barley alkaloids were tested for
allelopathy in a laboratory bioassay. Hordenine and
gramine were applied at three different
concentrations (0, 15 and 50 ppm) to surface-
sterilized Sinapis alba seeds on filter paper and
incubated in the dark for three days. Both hordenine
and gramine inhibited radicle growth of Sinapis
alba by increasing both size and number of
vacuoles, disorganizing organelles and damaging
the cell wall. The cell wall from the control
treatment was uniform while cell wall from alkaloid
treatment was irregular (i.e. in some part it was
thinner while in other it was very thick) [76].
Other phytotoxic compounds were also
released by barley including vanillic acid,
chlorogenic acid, p-coumaric acid and ferulic acid.
These phenolic acids significantly inhibited seed
germination and radicle and shoot growth of green
foxtail (Setaria viridis), which is a typical grass
© by PSP Volume 28 No. 2A/2019 pages 1040-1049 Fresenius Environmental Bulletin
weed of arable land [77]. The evidence of
morphological changes caused by barley
allelochemicals suggests that the presence and
release of those biologically active metabolites
from barley may contribute to the control of weeds
on arable land [76, 77].
Rye. Natural compounds from rye (Secale ce-
reale) with high allelopathic activity can also be
used as a good source of natural herbicides [78].
The weed- suppressive ability of rye is due to the
presence of the benzoxazinoid, 2,4-dihydroxy-1,4-
benzoxazin-3-one (DIBOA) and its breakdown
product, 2-benzoxazolinone (BOA) [79]. The effec-
tiveness and mode of action of DIBOA and BOA
on cucumber (Cucumis sativus) seedlings was
checked by electron and light microscopy. BOA
inhibited the root growth and reduced the number
of lateral roots by 77-100%. DIBOA also slowed
root growth but had no effect on the number of
lateral roots. Both compounds reduced the regener-
ation of root cap cells, increased cytoplasmic vacu-
olation, reduced ribosome density and number of
mitochondria and interfered with lipid catabolism.
Disturbance in cell ultrastructure revealed that both
DIBOA and BOA reduce root growth as a result of
disrupting lipid metabolism, reducing protein syn-
thesis and reducing transport or secretory capabili-
ties because of underdeveloped dictyosomes [78].
Sorghum. The allelopathic proerties of
sorghum have been studied for decades [80]
because of its inhibitory effect on weed growth by
releasing hydrophobic compounds into the
rhizosphere [81]. The bioactive compounds isolated
from sorghum root exudates mainly consist of a
dihydroquinone that was quickly oxidised to a p-
benzoquinone known as sorgoleone [80].
Sorgoleone when tested at 50 μM against a
wide range of weeds (Abutilon theophrasti, Datura
stramonium, Amaranthus retroflexus, Setaria
viridis, Digitaria sanguinalis and Echinochloa
crusgalli) in a nutrient medium for 10 days caused
growth inhibition. The effect of 10 μM sorgoleone
on weeds in a laboratory bioassay suggested that
sorgoleone is a potential herbicide and contributes
to sorghum allelopathy [81]. Further studies by [82]
showed that the stunted growth of weeds in the
presence of sorgoleone is due to its interference
with photosynthesis.
Sunflower. Sunflower (Helianthus annuus)
has a high level of secondary metabolites that are of
commercial interest. The crude extract of shoots
showed an inhibitory effect on germination of
lettuce (Lactuca sativa) seeds [83]. In both
greenhouse and laboratory experiments the water-
soluble extract from sunflower leaf, stem, flower
and root inhibited seed germination, radicle
elongation, radicle weight increase, hypocotyl
elongation and hypocotyl weight increase of wild
barley (Hordeum spontaneum) [84]. Plant height
and weight of wild barley was also reduced
significantly when it was grown in soil previously
used by sunflower. Incorporation of fresh sunflower
roots and shoots into soil released allelopathic
compounds that inhibited the germination, and the
height and weight increase of barley [84]. [85]
observed similar effects when they treated bambara
groundnut (Vigna subterranea) seeds with
sunflower (shoot and root) extracts on a filter paper
in the dark for 5 d under laboratory conditions.
Both radicle and shoot lengths were negatively
affected by sunflower exudates. The water-soluble
allelochemicals of sunflower could be used in weed
management programmes [84].
Allelochemicals of other plant species. Gar-
lic has been cultivated as a food ingredient and as a
medicine for almost 4000 years. In the last few
decades researches has been done to confirm the
health benefits related to Garlic including microbial
infections and anticancer. Recently it has been ob-
served that most of the biologically active com-
pounds isolated from garlic contain sulphur [86].
The sulphur containing compounds were proved to
be good nematicides and insecticides [87].
Vulpia myros (silver grass), an annually
growing winter grass, is one of the best examples
that were extensively studied for an allelopathic
effect on other plant species. [88] started a series of
experiments, which provided support for the
concept of V. myros allelopathy. In the first set of
experiments, the aqueous extracts of decomposed
plant residue collected at various time-points from
V. myros were applied to wheat seeds. The water-
soluble extract at high concentrations significantly
inhibited germination while at low concentration it
delayed germination of wheat seeds. The residues
also showed an inhibitory effect on coleoptile and
especially on growth [88]. After that successful
experiment the authors tried to purify, quantify and
characterise the compounds of interest by gas
chromatography MS (GC−MS). The extracts
from V. myros were fractioned by gas
chromatography (GC) through a wie-bore packed
column. The fractions showed bioactivity towards
wheat were collected and were identified by MS
[89]. In pursuit of identification they have
characterised 20 active compounds (Table 1), out of
which syringic acid, dihydroferulic acid, vanillic
acid, p-hydroxybenzenepropanoic acid and succinic
acid were present in much higher amounts than
dihydrocinnamic acid and catechol. The identified
compounds accounted for 0.05% of the dry weight
of V. myros residues.
The identified compounds were then utilised
in bioassays to test for their biological role. Each
individual compound exhibited characteristic
behaviour towards the test plant, wheat. Each of the
© by PSP Volume 28 No. 2A/2019 pages 1040-1049 Fresenius Environmental Bulletin
Dried yield and phytotoxic strength of allelochemicals isolated from ether extract of V. myros plant
residue [modified table from An et al. [89] and An et al. [90]]
concentration (ppm)
I50 (ppm)
Chemical name
Dry weight (%)
Protocatechuic acid
Succinic acid
Dihydrocaffeic acid
Syringic acid
p-Hydroxybenzoic acid
Vanillic acid
p-Hydroxyphenyl acetic
propanoic acid
Gentisic acid
p-Coumaric acid
Ferulic acid
propanoic acid
Dihydrocinnamic acid
Salicylic acid
Benzoic acid
Total dry weight of ether extract was 306.1 mg from 100 g of V. myros,wholeplant residue. % dry weight: dry weight of a
compound relative to total dry weight of whole plant residue.
Threshold concentration: the concentration at which a compound started growth inhibition of wheat coleoptiles and roots.
I50 is the concentration of compound at which it caused 50% inhibition of coleoptile and root growth in the test plant.
compounds caused greater reduction of root
elongation than coleoptile elongation.
Dihydrocinnamic acid and catechol had high
allelopathic effects even at very low concentrations
[90, 91].
Plants in the genus Ophiopogon are also
famous for a wide variety of biologically active
compounds; one of the best-studied is Ophiopogon
japonicus commonly known as dwarf lily turf. O.
japonicus was initially known for its medicinal
value but was latterly discovered to be an
allelopathic plant. The methanolic extract from the
roots of O. japonicus reduced root and hypocotyl
growth in lettuce. Salicyclic acid and p-
hydroxybenzoic acid were identified as an
allelochemicals in O. japonicus by NMR ( [92]
Root exudates of buckwheat (Fagopyrum
esculentum) are also a good source of allelopathic
compounds including vanillic acid, gallic acid 4-
hydroxyacetophenone. All three compounds have
inhibitory effects on the growth and development of
other plant species [93]. Vanillic acid from
germinating watermelon seeds has also inhibited
the shoot growth of lettuce and tomato but
stimulated the shoot growth of amaranth and
barnyard grass in a laboratory bioassay [94].
In allelopathy one species releases bioactive
secondary metabolites to affect the growth and
development of other species. Various plant species
are capable of releasing biologically potent
compounds that can be actively used as
allelochemicals against weeds, herbs,
microorganisms and nematodes. The compounds
(phenolics, alkaloids, oligosaccharides, etc.) that
are released from various plant organs under
favourable conditions have the ability to contribute
towards a complex set of interactions in the
rhizosphere. For example, terpenoids,
isothiocynates and phenolic compounds from
various crop species can be used as weedicide,
herbicides and against seed borne fungi. Also, the
leaf extracts from Betula pubescens and
polysulphides from garlic can be used as a potential
nematocide against parasitic neamatodes in the
infected soils.
© by PSP Volume 28 No. 2A/2019 pages 1040-1049 Fresenius Environmental Bulletin
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Received: 14.05.2018
Accepted: 06.12.2018
Amjad Iqbal
Associate Professor, Department of Agriculture,
Garden Campus, Abdul Wali Khan University
Mardan, 23200, Pakistan
... They indicated optimization of economic results could be achieved by a better management of production resources. Iqbal et al. [2] reviewed the way of promotion green agriculture and controlling pollution in their study indicating plants are sources of diverse classes of natural products. Status of bioenergy and requirements in biogas production was examined in Turkey by Denli et al. [3] which was revealed the potential sources such as raw material from agricultural areas and the importance of energy production via biogas in Turkey. ...
... The TBP can be calculated using the data in Tables 1 and 2 with the following equation: TABLE 1 Selected field crop productions, waste types, moisture rates, waste-product rates, sub-thermal values and availability rates [1,2,5,6,7,9,11,14,15,16,17,18,20,21,22,23,24,25,26,27,28,29,30]. ...
Full-text available
Agricultural crops are grown in large quantities and agricultural biomass residues are remained from this production in Turkey. In this study, biomass residues amount was calculated from the arable field crops and horticultural fruit production in Turkey and its spatial distribution map was developed according to provinces in Turkey. The potential energy values of these biomass residues was also calculated for Turkey. With the study, the potential provinces that could establish a biomass energy plant were identified. According to TUİK [13], theoretical biomass potential which was obtained from arable field crop production waste was about 50.9, while theoretical energy potential was 853.3 PJ and available energy potential was about 291.8 PJ, respectively. Theoretical biomass potential obtained from pruning residues in horticultural fruit production was about 4.7, and theoretical energy potential were 85.7 PJ, and available energy potential was about 68.5 PJ. The total theoretical biomass potential which was obtained from both field crop and horticultural fruit was 55.6, theoretical energy potential was 939.0 PJ (22,425.5 ktoe), available energy potential was 360.3 PJ (8,604.8 ktoe). When the biomass residue map and the energy values that can be obtained from biomass waste observed, the provinces which have over to 1 million tons solid waste biomass potential were
... Allelochemicals from rice exudates include phenolics, fatty acids, benzoxazinoids, and terpenoids. The compounds present in momilactone that inhibits weed growth are a diterpenoid flavone (5,7,4′trihydroxy-3′,5′-dimethoxyflavone (Tricin)); a cyclohexenone flavone (5,7,4′-trihydroxy-3′,5′-dimethoxy flavone); and a cyclohexanone (3-isopropyl-5-acetoxycyclohex-2-enone) (Iqbal et al., 2019). Chung et al. (2002) noted that the husk extracts of the rice variety, Janganbyeo contained nine compounds, including salicylic acid, which had the highest inhibiting impact on the total seedling length and dry weight of barnyard grass. ...
Full-text available
Rice is a key crop for meeting the global food demand and ensuring food security. However, the crop has been facing great problems to combat the weed problem. Synthetic herbicides pose a severe threat to the long-term viability of agricultural output, agroecosystems, and human health. Allelochemicals, secondary metabolites of allelopathic plants, are a powerful tool for biological and eco-friendly weed management. The dynamics of weed species in various situations are determined by crop allelopathy. Phenolics and momilactones are the most common allelochemicals responsible for herbicidal effects in rice. The dispersion of allelochemicals is influenced not only by crop variety but also by climatic conditions. The most volatile chemicals, such as terpenoids, are usually emitted by crop plants in drought-stricken areas whereas the plants in humid zones release phytotoxins that are hydrophilic in nature, including phenolics, flavonoids, and alkaloids. The allelochemicals can disrupt the biochemical and physiological processes in weeds causing them to die finally. This study insight into the concepts of allelopathy and allelochemicals, types of allelochemicals, techniques of investigating allelopathic potential in rice, modes of action of allelochemicals, pathways of allelochemical production in plants, biosynthesis of allelochemicals in rice, factors influencing the production of allelochemicals in plants, genetical manipulation through breeding to develop allelopathic traits in rice, the significance of rice allelopathy in sustainable agriculture, etc. Understanding these biological phenomena may thus aid in the development of new and novel weed-control tactics while allowing farmers to manage weeds in an environmentally friendly manner.
... Such chemicals could be obtained from flowers, stem, leaves and roots etc. These chemicals are commonly called as phytotoxins or allelochemicals (Iqbal et al., 2019). With many other naturally found compounds, these chemicals produces a wide range of biological effects with their capacity and can be moderately beneficial for weed management in farming systems. ...
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Heavy doses of synthetic weed control chemicals have facilitated herbicide resistance in weeds as well as predicted to possess toxicities. Natural compounds can be screened as potential herbicides which are more cost-effective, efficacious, selective, and environmentally safe. Experiments were conducted on selected weeds (Rumex dentatus, Euphorbia helioscopia, Chenopodium album, Avena fatua, Phalaris minor) to study the allelopathic potential of Rhazya stricta. Experiments were performed using a medium of 0.75 % (w / v) agar, filter paper, and soil. Parameters studied for assessing allelopathic effects were germination inhibition (%) along with the reduction in radicle and plumule length (cm). Results showed that seed germination of R. dentatus, P. minor, and C. album is inhibited by R. stricta allelochemicals. Minimum germination for C. album was noted whereas a non-significant effect on the germination of E. helioscopia, T. aestivum, and A. fatua was observed. Leaf extract of R. stricta on the agar, filter paper, and the soil inhibited the radicle and plumule length (cm) of all the test species. Results have indicated that even though radicle length and germination of T. aestivum are not affected by leaf extract of R. stricta, the plumule length was substantially decreased. The retarding effect of growth on wheat seedlings indicates that R. stricta might not be an acceptable candidate for weed control under field conditions.
... The hydrophobic compound sorgoleone [13], which is exuded from root hairs of sorghum seedlings [14] causes most of the allelopathy that is associated with sorghum [15,16], and reduces sorghum germination and seedling growth through autotoxicity [17]. Apart from sorgoleone, sorghum produces water-soluble compounds, dhurrin and phenolic acids [18,19] which are believed to cause short-term growth suppression of susceptible plants [20,21,22]. ...
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Allelopathic sorghum aqueous extracts can be used as sprays against weeds of arable lands. Water-soluble allelochemicals in the aqueous extracts may also negatively affect crops. Root aqueous extracts from the South African landrace sorghum IS9456 and the Botswanan commercial variety Mahube, with high (584.69 µg mg-1 root fresh weight) and low (17.38 µg mg-1 root fresh weight) sorgoleone contents respectively, were tested on germination, radicle length, plumule length and dry weight of goosegrass [Eleusine indica (L.) Gaertn], blackjack [Bidens pilosa (L.)], maize [Zea mays (L.)], soya bean [Glycine max (L.) Merr.] and wheat [Triticum aestivum (L.)]. Factors in five glasshouse experiments were the two sorghum varieties and four root extract solutions (0%, 5%, 10% and 20%) (w/v) arranged in a randomised complete block design with six replications. There was no significant effect (P>0.05) of variety and root aqueous extract on germination, radicle length, plumule length and dry weight of maize and on germination of wheat and goosegrass. The sorghum accession IS9456 significantly (P<0.05) reduced plumule length and dry weight of wheat and goosegrass and germination, plumule length and dry weight of soya bean and blackjack compared to Mahube. Increasing strength of root aqueous extract solution significantly (P<0.001) reduced plumule length and dry weight of wheat and goosegrass as well as germination and dry weight of soya bean and blackjack. Extracts from IS9456 had greater inhibitory effects on crop and weed germination and growth compared to those from Mahube. Due to its low sorgoleone content and weak weed suppression from its root aqueous extracts, Mahube may have low potential for use in allelopathic weed control. The sorghum accession IS9456, which also produces very high sorgoleone content, may be used in integrated weed management exploiting allelopathy from both sorgoleone and water-soluble allelochemicals, although farmers will have to be careful in terms of crop rotations since the aqueous extracts also inhibit germination and growth of some crops. Field studies may be required to further confirm allelopathic effects of root aqueous extracts from IS9456.
... The increasing amount of leaf litter accumulation in the soil makes soil not only rich in organic carbon and nutrient but also allelochemical. This is particularly because the compound is also present in the leaf (Iqbal et al. 2019). The higher amount of leaf litter accumulation, the more likely allelochemical accumulated in the soil and the impact is more severe. ...
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Indonesia is the second-largest vanilla production and the third-largest cocoa production in the world, but it sustained for a short period. The unsustainability of these crops is speculated to occur because of the change in leaf litter accumulation which affected the sustainability of soil organic carbon that plays an important role in maintaining soil health and fertility. To find out methods that could improve the sustainability of the production, a literature review was conducted. The articles, related to the sustainability of vanilla and cacao production, were collected using Google Scholar, Wiley Online Library, ResearchGate, and Google Chrome brows-er. Keywords were employed to find the articles including soil organic carbon, cocoa plantation, vanilla, leaf litter, and allelochemical. This current article review found that introducing crop by clearing of previously existing vegetation could severely reduce the rate of leaf litter accumulation. Consequently, in a prolonged period, the soil organic carbon and soil fertility are very low and are unable to support the healthy growth and production of the crops. To restore production, the plantation then is returned to more traditional agroforestry such as replanting shading trees and addition of mulch. However, in the higher density of canopy, the crop production is low attributed partly to the decreasing soil pH which increases the impact of allelochemical. This review concluded that the sustainability of leaf litter accumulation is crucial to maintain soil health, but mitigation is required to reduce the impact of allelochemical accumulation.
... At present, allelopathy is considered an important reason for the dominance of plants in ecological competition, and plants with strong allelopathy are generally the ecological dominant population (Scognamiglio and Schneider, 2020). Because the competition among plants usually inhibits the growth of other individuals by secreting large quantities of allelochemicals and preempt the basic ecological niche of other plants to obtain more space, light, water and nutrients to meet their physiological needs for growth and development (Iqbal et al., 2019). For example, walnut tree secretes walnut quinone to inhibit the growth of surrounding weeds, showing ecological advantages. ...
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Artemisia argyi is widely distributed in Asia, and it often becomes the dominant population in the field because of its strong ecological niche competitiveness. Allelochemicals secreted by plants are generally considered an important reason for their dominance in ecological competition. In this study, the allelochemicals in A. argyi were screened by a series of experiments and their mechanisms were explored via transcriptomics. First, the inhibitory effects of A. argyi on Echinochloa crusgalli , Setaria viridis , Portulaca oleracea and Amaranthus retroflexus were evaluated. Then, we carried out a qualitative and quantitative analysis of the chemical composition of the aqueous extract of A. argyi to screen for potential allelochemicals that can inhibit weed growth. Four potential allelochemicals were quantified: neochlorogenic acid (5-CQA), chlorogenic acid (3-CQA), cryptochlorogenic acid (4-CQA), and caffeic acid (CA). Coincidentally, their allelopathic effects on weeds seemed to be identical to their content, in the order CA>4−CQA>5−CQA>3-CQA. These findings suggested that CA might be the main allelopathic compound in the aqueous extract of A. argyi . Subsequently, the allelopathic effect and molecular mechanism of CA on S. viridis leaves were investigated. The physiological results showed that CA significantly induced reactive oxygen species (ROS) production, led to malondialdehyde (MDA) accumulation, and disrupted enzyme activities (POD, SOD, CAT) in S. viridis leaves. Moreover, transcriptome results revealed that CA inhibited S. viridis growth by downregulating multiple genes involved in gibberellin (GA) and phytoalexin biosynthesis and Mitogen-activated protein kinase (MAPK) signaling pathways. In addition, differentially expressed genes (DEGs) related to the biosynthesis and signaling pathways of phytohormones were verified by Quantitative Real-Time PCR (RT-qPCR). Taken together, this study may be the first to identify allelochemicals and explore their molecular mechanism about A. argyi . Importantly, the ecological advantages of A. argyi could be applied to ecological regulation and the development of botanical herbicides.
... It is now known that sorghum cultivars produce three key allelopathic compounds, namely dhurrin (Blomstedt et al. 2012;Bjarnholt et al. 2018), sorgoleone (Dayan et al. 2010;Uddin et al. 2014;Pan et al. 2018) and simple phenolic acids (Alsaadawi et al. 2015). These can enter the environment through volatilisation, foliar leaching, root exudation, residue decomposition or through leaching from plant litter (Iqbal et al. 2019). Allelochemicals from both the previous (Weston et al. 2013) and current season sorghum crop (Alsaadawi et al. 2015) can affect growth of other plants. ...
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Soil microorganisms found in shrub-meadow ecosystems are highly heterogeneous and extremely sensitive to grazing, but changes in microbial compositional and functional heterogeneity during grazing exclusion (GE) have been largely overlooked compared to community diversity. We collected soil samples from heavily grazed plots (6.0 sheep/ha) and GE plots (matrix and patch areas in both), and used a combination of next-generation sequencing, vegetation features, and the associated soil property data to investigate the effect of GE on the composition and function of microbial communities (bacteria fungi, and archaea) in 0–10 cm soils. Regarding community composition, the proportions of species in bacteria, fungi, and archaea were 97.3, 2.3, and 0.4%, respectively. GE significantly affected the species diversity of fungi and archaea but not that of bacteria. GE decreased the heterogeneity of bacteria (2.9% in matrix and 6.2% in patch) and archaea (31.1% in matrix and 19.7% in patch) but increased that of fungi by 1.4% in patch. Regarding community function, enzyme diversity and heterogeneity were increased by 10.4 and 9.4%, respectively, in patch after 6 years of fencing, exemplifying a high level of microbial functional redundancy. The Kyoto Encyclopedia of Genes and Genome pathways—cell growth and death, translation, digestive system, and nucleotide metabolism—were functional biomarkers (linear discriminant analysis effect size method) in matrix-non-grazed plots, whereas lipid metabolism, xenobiotics biodegradation and metabolism, and metabolism of terpenoids and polyketides, cell motility, cancer: overview, endocrine system, and membrane transport were biomarkers in patch-non-grazed plots. Additionally, GE improved the capacity for fatty acid metabolism but decreased the abundance of methane-producing archaea by 42.9%. Redundancy analysis revealed that the factors that affected microbial composition the most were soil aggregates, soil moisture, and the number of plant species, whereas those that affected microbial function the most were soil available phosphorus, soil temperature, and shrub canopy diameter. Our results quantified soil microbial heterogeneity, emphasizing the different responses of the composition and function of bacteria, fungi, and archaea to GE in alpine shrubs and meadows.
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The root extracts and root exudates from the Taxus chinensis var. mairei had significant promote effects on growth of Camptoteca acuminata seedlings. Four taxane chemicals, cephalomannine, 10-deacetylbacatin III, paclitaxel and 7-Epi-10-deacetyl-paclitaxel, were isolated from T. chinensis var. mairei root extracts and their structures were identified by spectroscopic analysis. The chemicals were detected in T. chinensis var. mairei root exudates, rhizosphere soils, and their concentrations ranged from 0.01 to 5.90 μg/g. At an approximate concentration determined in T. chinensis var. mairei root exudates, all four chemicals significantly promoted the growth of C. acuminata seedlings. Therefore, four chemicals from T. chinensis var. mairei root exudates may act as allelochemicals accelerating growth of C. acuminata seedling. There were significant relationships between growth of C. acuminata seedlings, soil properties, enzyme activities and microbial community under allelochemicals’ application. The results provide a reference for in-depth understanding of C. acuminata and T. chinensis var. mairei interactions. © 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
The article presents the results of studies of the influence of exometabolites in plants of different soybean varieties and technologies of their cultivation on the aggressiveness and intensity of sporulation of fungi isolates Fusarium graminearum Schwabe. The object of the study were plant exometabolites of soybean varieties: Suzirya of selection of National Research Center of the Institute of Agriculture of NAAS of Ukraine and Kent of selection of Saatbau Linz in Austria. Since organic production denies the use of mineral fertilizers and chemical plant protection products, an alternative to them is the use of technologies with biological products of different action. Therefore, of these varieties of soybean plants were grown according to the technologies developed in the companies: Filazonit Ukraine LLC, Modern Agricultural Technologies LLC, A-Rice LLC, as well as in the company BTU-Center, PE. Found that exometabolites of studied soybean varieties, grown on listed technologies, lead to increased aggressiveness of isolates of the fungus F. graminearum. Thus, against the background of exometabolites of soybean plants of the Suzirya variety, the index of seedling damage ranged from 21.3% to 29.8%, and against the background of exometabolites of soybean plants of the Kent variety — from 21.14% to 25.46%. This indicates their medium aggressiveness and stabilizing selection in the fungus population. It is established that the exometabolites of the studied soybean cultivars grown by the listed technologies lead to a decrease in the intensity of sporulation of fungus isolates F. graminearum compared to control. Thus, against the background of exometabolites of soybean plants of the Suzirya variety, the index of seedling damage ranged from 5,7·106 cells/ml to 12,11·106 cells/ml, and against the background of exometabolites of soybean plants of the Kent variety — from 4,25·106 cells/ml to 10,2·106 cells/ml. This indicates their average aggressiveness and stabilizing selection in the population of the fungus on this basis. Thus, the obtained results of studies point to a significant influence of metabolic products of plants of different varieties of soybean and their cultivation technology on physiological and biochemical properties of pathogenic fungi F. graminearum.
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A study was conducted to test the aphicidal activity of the ethanol leaf extract of six plant species of the most widely spread plants in Jordan. LC50 and LC90 were calculated using SPSS program. Completely Randomized Design (CRD) evaluation experiment was conducted to test the six plant species against the green peach aphid (GPA) Myzus persicae which was maintained in two cultures, in the Lab and in the green house for ten generations to get a susceptible strain before conducting the bioassay. Ethanol leaf extracts were obtained by soaking and then concentrated and dried. Dipping method was used in the bioassay. Results were significantly different in the toxicity assessment and in the CRD evaluation. The LC50 for the leaf extract of Ricinus communis L was the lowest (553 ppm) and for Robinia pseudoacacia L was the second most toxic plant extract (1150 ppm) after 24 hours, while Lantana camara L ethanol leaf extract was the least toxic (6660 ppm). CRD evaluation showed that Robinia pseudoacacia had 76.46%, followed by Ricinus communis which had 58.6% mortality rates, respectively. On the other hand Neruim oleander Mill caused the least mortality rate 25.2%, compared to the negative control and the positive control (Cypermethrin) which caused 3.24% and 90.82% mortality rates after 24 hours, respectively.
Conference Paper
A study was conducted to test the aphicidal activity of the ethanol leaf extract of six plant species of the most widely spread plants in Jordan. LC50 and LC90 were calculated using SPSS program. Completely Randomized Design (CRD) evaluation experiment was conducted to test the six plant species against the green peach aphid (GPA) Myzus persicae which was maintained in two cultures, in the Lab and in the green house for ten generations to get a susceptible strain before conducting the bioassay. Ethanol leaf extracts were obtained by soaking and then concentrated and dried. Dipping method was used in the bioassay. Results were significantly different from the control either in the toxicity assessment or in the CRD evaluation. The LC50 for the leaf extract of Ricinus communis was the lowest (553 ppm) and for Robinia pseudoacacia was the second most toxic plant extract (1371 ppm) after 24 hours, while Lantana camara ethanol leaf extract was the least toxic (6660 ppm). CRD evaluation showed that Robinia pseudoacacia had 76.46%, followed by Ricinus communis which had 58.6% mortality rates, respectively. On the other hand Neruim oleander caused the least mortality rate 25.2%, compared to the negative control and the positive control (Cypermethrin) which caused 3.24% and 90.82% mortality rates after 24 hours, respectively.
Natural sulfur compounds from plants, bacteria, fungi and animals frequently exhibit interesting biological activities, such as antioxidant, antimicrobial and anticancer activity. Considering the recent developments in medicine (e.g. oxidative stress in ageing, antibiotic resistant bacteria, and selective anticancer agents) and Agriculture (e.g. 'green'; pesticides), several of these compounds have become the focus of interdisciplinary research. Among the various sulfur agents isolated to date, polysulfides, such as diallyltrisulfide, diallyltetrasulfide (from garlic) and dipropyltrisulfide, dipropyltetrasulfide (from onion), are of particular interest, since they combine an unusual chemistry and biochemical mode(s) of action with a distinct biological activity, which includes antimicrobial activity and cytotoxicity against certain cancer cells. As part of this PhD thesis, the activity of diallyltrisulfide and diallyltetrasulfide against the fairly 'robust'; Caco-2 colon cancer cell line and induction of apoptosis and cell cycle arrest in U937 cells have been confirmed. Accordingly, diallyltetrasulfide triggered the programmed cancer cell death- both via the extrinsic and intrinsic pathway. Similarly, these polysulfides showed a good activity in nematode toxicity assays considering them as potential green nematicides. Controls with the long chain carbon analogue 1,9-decadiene eliminate the possibility of solely lipophilic effects of diallyltetrasulfide and, together with the 'ranking'; of activity, point toward a special sulfur redox chemistry which emerges when shifting from the di- to the trisulfide. The electrochemical studies and thiol oxidation assays, however, count against the notion of diallyltrisulfide and diallyltetrasulfide as effective oxidants. On the contrary, the rather negative oxidation and reduction potentials associated with these agents point toward a reducing chemistry, which is confirmed in the Nitrotetrazolium Blue assay. It is therefore likely that diallyltrisulfide and diallyltetrasulfide are reduced inside the cancer cells to perthiols and hydropolysulfides, which in turn trigger a lethal oxidative burst via superoxide radical anion formation. Further interdisciplinary studies are required to investigate in more detail the rather complicated chemical and biochemical processes which ultimately may explain the biological activity which is clearly associated with many natural polysulfides.
Background and aims: Cress-seed (Lepidium sativum) exudate exerts an allelochemical effect, promoting excessive hypocotyl elongation and inhibiting root growth in neighbouring Amaranthus caudatus seedlings. We investigated acidic disaccharides present in cress-seed exudate, testing the proposal that the allelochemical is an oligosaccharin-lepidimoic acid (LMA; 4-deoxy-β-l-threo-hex-4-enopyranuronosyl-(1→2)-l-rhamnose). Methods: Cress-seed exudate was variously treated [heating, ethanolic precipitation, solvent partitioning, high-voltage paper electrophoresis and gel-permeation chromatography (GPC)], and the products were bioassayed for effects on dark-grown Amaranthus seedlings. Two acidic disaccharides, including LMA, were isolated and characterized by electrophoresis, thin-layer chromatography (TLC) and nuclear magnetic resonance (NMR) spectroscopy, and then bioassayed. Key results: Cress-seed exudate contained low-Mr, hydrophilic, heat-stable material that strongly promoted Amaranthus hypocotyl elongation and inhibited root growth, but that separated from LMA on electrophoresis and GPC. Cress-seed exudate contained ∼250 µm LMA, whose TLC and electrophoretic mobilities, susceptibility to mild acid hydrolysis and NMR spectra are reported. A second acidic disaccharide, present at ∼120 µm, was similarly characterized, and shown to be β-d-xylopyranosyl-(1→3)-d-galacturonic acid (Xyl→GalA), a repeat unit of xylogalacturonan. Purified LMA and Xyl→GalA when applied at 360 and 740 µm, respectively, only slightly promoted Amaranthus hypocotyl growth, but equally promoted root growth and thus had no effect on the hypocotyl:root ratio, unlike total cress-seed exudate. Conclusions: LMA is present in cress seeds, probably formed by rhamnogalacturonan lyase action on rhamnogalacturonan-I during seed development. Our results contradict the hypothesis that LMA is a cress allelochemical that appreciably perturbs the growth of potentially competing seedlings. Since LMA and Xyl→GalA slightly promoted both hypocotyl and root elongation, their effect could be nutritional. We conclude that rhamnogalacturonan-I and xylogalacturonan (pectin domains) are not sources of oligosaccharins with allelochemical activity, and the biological roles (if any) of the disaccharides derived from them are unknown. The main allelochemical principle in cress-seed exudate remains to be identified.
The chemical composition of volatile compounds from the tree of heaven leaves (Ailanthus altissima (Mill.) Swingle) was analysed, for the first time, by gas chromatography-mass spectrometry (GrC-MS). The volatiles were isolated from fresh as well as from dried leaves of young and old trees. Forty-nine compounds were identified, representing 88.5-96.3% of total volatiles. The main constituents were aliphatic C-6-compounds (alcohols, aldehydes, acids, esters) 30.8-59.7%, sesquiterpene compounds, especially hydrocarbons (beta-caryophyllene, alpha-humulene, gamma- and delta-cadinene, calarene) 11.3-57.4%, oxygenated monoterpenes (linalool, geraniol, a-terpineol) 3.6-9.4% and other compounds 4.5-12.0%. The stage of plant development and the air-drying of plant material have a strong influence on the qualitative and quantitative composition of ailanthus volatile compounds.
This work re-examines the idea that xyloglucans of the primary cell walls of graminaceous monocotyledons differ from those of most other higher plants in lacking α-L-fucose residues. Suspension-cultured cells of Festuca arundinacea Schreber (tall fescue grass) incorporated exogenous L-[1-3H]fucose into cell wall material. About 67% of the phenol-insoluble 3H could be extracted from these cell walls with 3.6 M KOH. About 40% of the KOH-extracted 3H was converted into products of apparent molecular weight ~ 200-2000 by Trichoderma cellulase, and a discrete peak of this material eluted from Bio-Gel P-2 at Kav 0.40 suggesting a nonasaccharide. On paper chromatography in two solvent systems, and HPLC on aminosilica, about 33 % of the 3H in this fraction co-migrated with an authentic nonasaccharide, Glc4Xyl3GalFuc (XXFG), which is generated from dicotyledonous xyloglucan by cellulase digestion. In addition, the [3H]nonasaccharide from Festuca and authentic XXFG yielded identical products when subjected to limited digestion with the fungal glycanase mixture, Driselase. Taken together, the evidence indicates for the first time that grass cell walls contained a small amount of fucosylated xyloglucan.