Shoots Of Cress Research Articles

A kaurene-type novel phytotoxic substance in Wedelia chinensis

Wedelia chinensis has been widely used as a traditional medicine and several bioactive compounds have been isolated. We investigated phytotoxic property and phytotoxic substances in the species. An aqueous methanol extract of W. chinensis inhibited the growth of roots and shoots of cress. The extracts were then purified by several chromatographic runs with monitoring the inhibitory activity and a phytotoxic substance was isolated. The substance was determined by spectral data to be a novel kaurene-type compound, wedelienone. Wedelienone inhibited the growth of cress and timothy (Phleum pratense L) at concentrations greater than 10–30 μM. These results suggest that wedelienone may contribute to the phytotoxic effects caused by the extracts.

Phytotoxic activity of crop residues from Burdock and an active substance

Problems related to weed management such as outbreaks of herbicide-resistant weeds have recently increased. An interesting approach to such problems is to use plant materials with phytotoxic activity. Burdock (Arctium lappa L.) is a biennial herb belonging to Asteraceae and is cultivated in several countries. The present study investigated the phytotoxic activity of burdock and its active substances. Extracts of both burdock leaves and roots inhibited the shoot and root growth of cress and barnyard grass, where the level of inhibition increased with increasing extract concentration. The leaf extracts had 2.0–2.5 times higher activity than the root extracts. Bioassay-guided separations of the leaf extracts led to isolation of a phytotoxic substance, onopordopicrin. Onopordopicrin significantly inhibited the shoot and root growth of cress and barnyard grass. The concentrations of the substance required for 50% growth inhibition were 0.27 and 0.26 mM for cress shoots and roots, respectively, and 1.86 and 0.35 mM for barnyard grass shoots and roots, respectively. The present results suggest that burdock leaves have high phytotoxic activity and onopordopicrin may play a major role in the activity. Burdock leaves may be a good resource for weed management.

Plant Growth Inhibitory Activity of the Extracts of Acmella oleracea and its Growth Inhibitory Substances

Aqueous methanol extracts of Acmella oleracea inhibited the growth of roots and shoots of cress ( Lepidum sativum), lettuce ( Lactuca sativa), Italian ryegrass ( Lolium multiflorum), and barnyard grass ( Echinochloa crus-galli) with the extract concentration-dependent manner. The extracts were then purified and 2 growth inhibitory substances were isolated and identified by spectral data as ( E,E)-2,4-undecadien-8,10-diynoic acid isobutylamide (compound 1) and nona-(2 Z)-en-6,8-diynoic acid 2-phenylethylamide (compound 2). Compound 1 inhibited the growth of cress roots and shoots at concentrations greater than 0.3 mM and that of barnyard grass root at concentrations greater than 0.03 mM. Compound 2 inhibited the growth of cress shoots and barnyard grass roots at concentrations greater than 1 mM. The inhibition on the seedling growth indicates that both compounds had growth inhibitory activity and may contribute to the inhibitory effect of A. oleracea extracts. This is the first report of having growth inhibitory activity of compounds 1 and 2 on plants.

Phytotoxic Substance with Allelopathic Activity in Brachiaria decumbens

The grass Brachiaria decumbens becomes naturalized and quickly dominant in non-native areas. It was hypothesized that phytotoxic substances of plants may contribute to the domination and invasion of the plants. However, no potent phytotoxic substance has been reported in B. decumbens. Therefore, we searched for phytotoxic substances with allelopathic activity in this species. An aqueous methanol extract of B. decumbens inhibited the growth of roots and shoots of cress (Lepidium sativum), lettuce (Lactuca sativa), timothy (Phleum pratense) and ryegrass (Lolium multiflorum) seedlings. The extract was then purified using chromatographic methods and a phytotoxic substance with allelopathic activity was isolated and identified by spectral analysis as (6R,9S)-3-oxo-α-ionol. These results suggest that this compound may contribute to the allelopathic effect caused by the B. decumbens extract and may be in part responsible for the invasion and domination of B. decumbens. Two other Brachiaria species, B. brizantha and a Brachiaria hybrid were also confirmed to contain (6R,9S)-3-oxo-α-ionol. Therefore, this compound may play an important role in the phytotoxicity of the Brachiaria species.

Nimbolide B and nimbic acid B, phytotoxic substances in neem leaves with allelopathic activity.

Neem (Azadirachta indica) has been widely used as a traditional medicine and several bioactive compounds have been isolated from this species, but to date no potent allelopathic active substance has been reported. Therefore, we investigated possible allelopathic property and phytotoxic substances with allelopathic activity in neem. An aqueous methanol extract of neem leaves inhibited the growth of roots and shoots of cress, lettuce, alfalfa, timothy, crabgrass, ryegrass, barnyard grass and jungle rice. The extracts were then purified by several chromatographic runs while monitoring the inhibitory activity and two phytotoxic substances were isolated. The chemical structures of the two substances were determined by spectral data to correspond to novel compounds, nimbolide B (1) and nimbic acid B (2). Nimbolide B inhibited the growth of cress and barnyard grass at concentrations greater than 0.1‒3.0 μM. Nimbic acid B inhibited the growth of cress and barnyard grass at concentrations greater than 0.3–1.0 μM. These results suggest that nimbolide B and nimbic acid B may contribute to the allelopathic effects caused by neem leaves.

Growth limiting effects on various terrestrial plant species by an allelopathic substance, loliolide, from water hyacinth

Water hyacinth (Eichhornia crassipes) is one of the most noxious invasive aquatic plants in many countries due to its rapid growth and reproduction rate. Most practical methods to control water hyacinth are mechanical removal of the plants, and chemical and biological controls with large expense for those treatments. For recovery of control costs, beneficial use options for water hyacinth after mechanical removal would be helpful. Therefore, we investigated possible allelopathic effects of extracts and isolated allelopathic substances in water hyacinth. An aqueous methanol extract of water hyacinth inhibited the growth of roots and shoots of cress (Lepidium sativum), lettuce (Lactuca sativa), alfalfa (Medicago sativa), timothy (Phleum pratense) and ryegrass (Lolium multiflorum). Increasing extract concentration increased the inhibition. These results suggest that water hyacinth may cause allelopathic effects and contain allelopathically active substances. The extract was then purified by several choromatographic runs with monitoring the inhibitory activity during all purification steps, and a main allelopathically active substance was isolated. The chemical structure of the substance was determined by spectral data as loliolide. Loliolide inhibited the growth of cress and ryegrass at concentrations greater than 3 and 10μM. The concentrations required for 50% inhibition of the root and shoot growth ranged from 12.7–27.5 to 27.5–49.7μM for cress and ryegrass, respectively. These results suggest that loliolide may be an allelopantic substance and contribute to the growth inhibitory effect of water hyacinth. A water extract of water hyacinth also inhibited all test plant species extract-concentration dependently and contained loliolide. In addition, powder of water hyacinth inhibited germination of barnyard grass in the greenhouse condition with powder-concentration dependently. Therefore, water hyacinth may potentially be useful as soil additive materials to control weeds in the sustainable agriculture.

Isolation and identification of a plant growth inhibitor from Tinospora tuberculata Beumee

Tinospora tuberculata Beumee has been used widely as a folk medicine and several bioactive compounds have been isolated. However, no herbicidal compound has been reported in this species. Therefore, we investigated the presence of phytotoxins in T. tuberculata. The aqueous methanol extracts of T. tuberculata inhibited the growth of roots and shoots of cress (Lepidum sativum L.), lettuce (Lactuca sativa L.), timothy (Phleum pratense L.) and barnyard grass (Echinochloa crus-galli (L.) Beauv.). The extract was then purified by several chromatographic runs with monitoring the inhibitory activity and the main phytotoxic substance was isolated. The chemical structure of the compound was determined by spectral data as syringin (4-[(1E)-3-Hydroxyprop-1-en-1-yl]-2,6-dimethoxyphenyl β-d-glucopyranoside). It inhibited the root and shoot growth of all test plant species at concentrations >10 µM. The concentrations required for 50 % inhibition of root and shoot growth of cress and lettuce ranged from 78.2 to 412 μM, and that of timothy and barnyard grass renged from 9.8 to 73.2 µM. Effectiveness of syringin on monocotyledonous (timothy and barnyard grass) plants was greater than that on dicotyledonous (cress and lettuce) plants. These results suggest that syringin may contribute to the allelopathic effect caused by the T. tuberculata extract.

Organ-specific-active allelopathic substance in red pine needles

An organ-specific-growth inhibitory substance was isolated from an aqueous methanol extract of red pine needles and determined by spectral data as 1-mono(16-hydroxyhexadecanoyl)glycerol. This substance inhibited root growth of cress (Lepidium sativum L.) and barnyard grass (Echinochloa crus-galli (L.) Beauv) seedlings at concentrations greater than 0.01 and 0.03 μM, respectively. The concentrations required for 50 % growth inhibition on roots of cress and barnyard grass were 0.16 and 3.4 μM, respectively. However, the inhibitory activity of the substance on shoots of cress and barnyard grass was very weak. The endogenous concentration of 1-mono(16-hydroxyhexadecanoyl)glycerol in the pine needles was 4.6 μmol kg−1. Two related compounds, 1-monohexadecanoylglycerol and 16-hydroxyhexadecanlic acid had no activity up to 1,000 μM on cress roots and shoots. The effectiveness of 1-mono(16-hydroxyhexadecanoyl)glycerol on root growth inhibition and the occurrence of 1-mono(16-hydroxyhexadecanoyl)glycerol in pine needles suggest the substance may play an important role in the allelopathy of red pine. Root-specific-growth-inhibition by the substance may be one of the strategies for red pine to compete with neighboring plants for nutrients and space because root growth of competitive plants may be very important for their whole plant development.

Identification of two phytotoxins, blumenol A and grasshopper ketone, in the allelopathic Japanese rice variety Awaakamai

Aqueous methanol extracts of the traditional rice (Oryza sativa) variety Awaakamai, which is known to have the greatest allelopathic activity among Japanese traditional rice varieties, inhibited the growth of roots and shoots of cress (Lepidium sativum), lettuce (Lactuca sativa), timothy (Phleum pratense), Digitaria sanguinalis, Lolium multiflorum and Echinochloa crus-galli. Increasing the extract concentration increased the inhibition, suggesting that the extract of Awaakamai contains growth inhibitory substances. The extract of Awaakamai was purified and two main growth inhibitory substances were isolated and determined by spectral data as blumenol A and grasshopper ketone. Blumenol A and grasshopper ketone, respectively, inhibited the growth of cress shoots and roots at concentrations greater than 10 and 30μmol/L. The concentrations required for 50% growth inhibition on cress roots and shoots were 84 and 27μmol/L, respectively, for blumenol A, and 185 and 76μmol/L, respectively, for grasshopper ketone. These results suggest that blumenol A and grasshopper ketone may contribute to the growth inhibitory effect of Awaakamai and may play an important role in the allelopathy of Awaakamai.

Two potent allelopathic substances in cucumber plants

Since cucumber plants are mostly discarded as large waste after crop harvesting, allelopathy of cucumber plants was investigated for possible weed management options and utilization of the waste. Two potent growth inhibitory substances were isolated from an aqueous methanol extract of cucumber ( Cucumis sativus L. cv. Phung Tuong) plants. These substances were determined as 9-hydroxy-4,7-megastigmadien-9-one (HMO) and (6 S,7 E,9 S)-6,9,10-trihydroxy-4,7-megastigmadien-3-one (THMO) by the analysis of MS, 1H NMR spectra and optical rotation. HMO inhibited the growth of cress ( Lepidium sativum L.) and Echinochloa crus-galli (L.) Beauv seedlings at concentrations greater than 0.3 and 1 μM, respectively. THMO inhibited the growth of cress and E. crus-galli seedlings at concentrations greater than 1 and 3 μM, respectively. The concentrations required for 50% growth inhibition on roots and shoots of cress and E. crus-galli were 2.4–29.3 μM for HMO and 8.1–52.2 μM for THMO. The endogenous levels of HMO and THMO in cucumber plants were 31.8 and 43.5 μg g −1 dry weight, respectively. These results suggest that HMO and THMO may be the causal factors for the growth inhibitory effect of cucumber plants. Therefore, cucumber plants may be potentially useful for weed management options in an agricultural setting, such as a cover crop and soil admixture, which should be investigated further in the field.

Allelopathy of red pine: isolation and identification of an allelopathic substance in red pine needles

Since red pine (Pinus densiflora Sieb. et Zucc.) often forms sparse forest floors where herbaceous plants do not grow well, allelopathy of red pine was investigated. A growth inhibitory substance was isolated from an aqueous methanol extract of red pine needles and determined by spectral data as abscisic acid-β-d-glucopyranosyl ester (ABA-GE). This substance inhibited root and shoot growth of cress and E. crus-galli seedlings at concentrations greater than 0.1 μM. The concentrations required for 50% growth inhibition on roots and shoots of cress were 0.23 and 0.61 μM, respectively, and those of E. crus-galli were 1.1 and 2.8 μM, respectively. The activity of ABA-β-d-glucosidase, which liberates free ABA from ABA-GE, in cress and E. crus-galli seedlings was 13–29 nmol mg−1 protein min−1. Endogenous concentration of ABA-GE in the pine needles was 4.1–21.5 μmol kg−1 and the concentration in soil water of the pine forest was 2.5 μM. The effectiveness of ABA-GE on growth inhibition and the occurrence of ABA-GE in pine needles and soil water suggest ABA-GE may play an important role in the allelopathy of red pine resulting in the formation of sparse forest floors.

Isolation and identification of potent allelopathic substances in rattail fescue

Aqueous methanol extracts of rattail fescue (Vulpia myuros) inhibited the growth of roots and shoots of cress (Lepidium sativum), lettuce (Lactuca sativa), alfalfa (Medicago sativa), timothy (Phleum pratense), Digitaria sanguinalis and Lolium multiflorum. Increasing the extract concentration increased the inhibition, suggesting that rat- tail fescue may have growth inhibitory substances and possess allelopathic potential. The aqueous methanol extract of rattail fescue was purified and two main inhibi- tory substances were isolated and identified by spectral data as (-)-3-hydroxy-b-ionone and (?)-3-oxo-a-ionol. Both substances inhibited root and shoot growth of cress at concentrations greater than 0.3 lM. The concentrations required for 50% growth inhibition on root and shoot growth of cress, lettuce, alfalfa, timothy, D. sanguinalis and L. multiflorum were 2.7-19.7 lM for (-)-3-hydroxy- b-ionone, and 2.1-34.5 lM for (?)-3-oxo-a-ionol. The concentration of (-)-3-hydroxy-b-ionone and (?)-3- oxo-a-ionol, respectively, in rattail fescue was 7.8 and 3.7 l gg -1 fresh weight. Considering the endogenous level and the inhibitory activity, (-)-3-hydroxy-b-ionone and (?)-3-oxo-a-ionol may work as allelopathic substances in rattail fescue through the growth inhibition of neighboring plant species.

Allelopathy of the moss Hypnum plumaeforme by the production of momilactone A and B

SummaryExtract of soil under colonies of Hypnum plumaeforme inhibited the growth of roots and shoots of cress, lettuce, lucerne, ryegrass, timothy, Digitaria sanguinalis and Echinochloa crus‐galli. Increasing the extract concentration increased the inhibition, which suggest that the soil may contain growth inhibitory substances and possess allelopathic potential. The extract of the soil under H. plumaeforme was purified and two main inhibitory substances were isolated and determined by MS and 1H‐ and 13C‐NMR spectral data as momilactone A and B. Momilactone A and B inhibited hypocotyls and roots of cress seedlings at concentrations >10 and 1 μm respectively. The endogenous concentration of momilactone A and B in H. plumaeforme was 58.7 and 23.4 μg g−1 dry weight respectively and the concentration of momilactone A and B in MS growth medium of H. plumaeforme was 4.3 and 6.4 μg g−1 dry weight of H. plumaeforme, respectively. These results suggest that momilactone A and B were probably secreted into the medium during the incubation and momilactone A and B found in the soil under H. plumaeforme may have been released by the moss. Therefore, growth inhibitory activity of the soil under H. plumaeforme may be caused by momilactone A and B, which may act as allelopathic agents of H. plumaeforme.

Isolation and identification of a potent allelopathic substance in Bangladesh rice

Aqueous methanol extracts of Bangladesh rice (Oryza sativa L. cv. BR17) inhibited the growth of roots and shoots of cress (Lepidium sativum), lettuce (Lactuca sativa), alfalfa (Medicago sativa), timothy (Phleum pratense), Digitaria sanguinalis, Echinochloa crus-galli and Echinochloa colonum. Increasing the extract concentration increased the inhibition, suggesting that the BR17 may have growth inhibitory substances and possess allelopathic potential. The aqueous methanol extract of the BR17 was purified and a main inhibitory substance was isolated and determined by spectral data as 2,9-dihydroxy-4-megastigmen-3-one. This substance inhibited root and shoot growth of cress and E. crus-galli seedlings at concentrations greater than 0.03 and 3 μM, respectively. The concentrations required for 50% growth inhibition on cress roots and shoots were 0.22 and 0.47 μM, respectively, and on E. crus-galli roots and shoots were 36 and 133 μM, respectively. These results suggest that 2,9-dihydroxy-4-megastigmen-3-one may contribute to the growth inhibitory effect of BR17 and may play an important role in the allelopathy of BR17. Thus, Bangladesh rice BR17 may be potentially useful for weed management in a field setting.

An allelopathic substance in red pine needles ( Pinus densiflora)

Aqueous methanol extracts of red pine (Pinus densiflora) needles inhibited the growth of roots and shoots of cress (Lepidium sativum), lettuce (Lactuca sativa), alfalfa (Medicago sativa), ryegrass (Lolium multiflorum), timothy (Pheleum pratense), Digitaria sanguinalis and Echinochloa crus-galli. Increasing the extract concentration increased inhibition, suggesting that the pine needles may have growth inhibitory substances and possess allelopathic potential. The aqueous methanol extract of the pine needles was purified, and a main inhibitory substance was isolated and determined by spectral data as 9alpha,13beta-epidioxyabeit-8(14)en-18-oic acid. This substance inhibited root and shoot growth of cress and Echinochloa crus-galli seedlings at concentrations greater than 0.1 mM. The endogenous concentration of the substance was 0.13 mmol/kg pine needle. These results suggest that 9alpha,13beta-epidioxyabeit-8(14)en-18-oic acid may contribute to the growth inhibitory effect of the pine needles and may play an important role in the allelopathy of red pine.

Allelopathy and the allelopathic activity of a phenylpropanol from cucumber plants

The growth inhibitory effect of cucumber (Cucumis sativus L.) plants after crop harvested was investigated. Aqueous methanol extracts of the cucumber plants inhibited the growth of roots and shoots of cress (Lepidium sativum L.), lettuce (Lactuca sativa L.), alfalfa (Medicago sativa L.), ryegrass (Lolium multiflorum L.), timothy (Pheleum pratense L.), crabgrass (Digitaria sanguinalis L.), Echinochloa crus-galli (L.) Beauv and Echinochloa colonum (L.) Link, and increasing the extract concentration increased the inhibition. These results suggest that cucumber plants may possess allelopathic activity. The aqueous methanol extract of cucumber plants was divided into ethyl acetate and aqueous fractions, and the growth inhibitory activity of ethyl acetate fraction was greater than that of aqueous fraction. Thus, ethyl acetate fraction was further purified and a main allopathically active substance in the fraction was isolated and determined as (S)-2-benzoyloxy-3-phenyl-1-propanol by spectral data. This substance inhibited root and shoot growth of cress seedlings at concentrations greater than 10 μM, and the concentration required for 50% inhibition of root and shoot growth was 21 and 23 μM, respectively. These results suggest that (S)-2-benzoyloxy-3-phenyl-1-propanol may contribute to the growth inhibitory effect of cucumber plants and may play an important role in cucumber allelopathy. Thus, cucumber plants may be potentially useful for weed management in a field setting.

Allelopathic Potential of Citrus junos Leaves and Abscisic Acid-Glucose Ester

The allelopathic potential of an aqueous methanol extract of Citrus junos leaves was investigated under laboratory conditions. The extract inhibited the growth of roots and shoots of cress (Lepidium sativum L.), lettuce (Lactuca sativa L.) and alfalfa (Medicago sativa L.) seedlings. Significant reductions in the root and shoot growth were observed as the extract concentration increased. Since abscisic acid -β-D-glucopyranosyl ester (ABA-GE) was found to be a major inhibitor in fruit peel of C. junos, ABA-GE in C. junos leaves was determined and the concentration was 540 μg kg-1 fresh weight in the leaves harvested on September 26, 2002. These results suggest that C. junos leaves possess allelopathic activity and could work as a weed inhibiting agent, which should be investigated further in the field for practical application.

Allelopathic Potential of Pueraria thunbergiana

The allelopathic potential of Pueraria thunbergiana was investigated under laboratory conditions. The powder of freeze-dried leaves of P. thunbergiana inhibited the germination and the growth of roots and shoots of cress, lettuce, timothy and ryegrass. Significant reductions in the germination and growth of roots and shoots were observed as the powder concentration increased in all bioassays. The putative compounds causing the inhibitory effect of the powder were isolated and determined by their spectral data as cis.trans- and trans,trans-xanthoxin