Determination of allelopathic properties of Acacia catechu (L.f.) Willd.

Plants possessing allelopathic potential could be used as a source of bio-herbicide to help decrease the use of synthetic herbicides. Acacia catechu (L.f.) Willd., a deciduous tree from the Mimosaceae family, has been reported to have medicinal properties. However, there have been no reports on the allelopathy of this tree. Therefore, the leaf extracts of A. catechu were examined for allelopathic potential using six concentrations: 0.001, 0.003, 0.01, 0.03, 0.1, and 0.3 g dry weight equivalent extract mL-1. The aqueous methanol extracts of A. catechu significantly suppressed the seedling growth of six test plants such as alfalfa, cress, lettuce, barnyard grass, Italian ryegrass, and timothy. The extracts inhibited the six test plants in a concentration-dependent manner. The shoot and root growth of all the test plant species were completely inhibited from the concentration of 0.3 g of dry weight equivalent extract mL-1, except the shoot growth of barnyard grass. Concentrations needed for 50% growth inhibition (I50 values) ranged from 0.004 to 0.043 g dry weight equivalent extract mL-1 for shoot growth, and 0.003 to 0.019 g dry weight equivalent extract mL-1 for root growth. Moreover, the I50 values indicated that the root growth of all the test plants was more susceptible to the A. catechu extracts than the shoot growth. The inhibitory effects of the extracts of A. catechu suggest that the extracts may contain allelopathic potential and, therefore, may be a potential candidate for the isolation and characterization of allelochemicals to develop an ecofriendly bio-herbicide

Allelopathic potential of Acacia pennata (L.) Willd. leaf extracts against the seedling growth of six test plants

Acacia pennata (L.) Willd (Mimosaceae), a woody climbing plant, is used as a traditional medicinal plant in the South and Southeast Asia regions and has been documented to have various pharmacological effects. However, the allelopathy of this plant still remains unclear. Thus, the allelopathic potential of A. pennata leaf extracts was examined against the seedling growth of dicot plants [alfalfa (Medicago sativa L.), cress (Lepidium sativum L.), and lettuce (Lactuca sativa L.)] and monocot plants [barnyard grass (Echinochloa crus-galli (L.) Beauv.), Italian ryegrass (Lolium multiflorum Lam.), and timothy (Phleum pratense L.)] at six different concentrations. The results showed that the A. pennata leaf extracts inhibited the seedling growth of all the test plant species at concentrations ≥3 mg dry weight (D.W.) equivalent extract mL-1. The inhibitory activity of the extracts against both shoot and root growth varied with concentration and tested plants. The concentrations required for 50% inhibition of the test plant shoots and roots were 1.5-16.1 and 1.4-8.6 mg D.W. equivalent extract mL-1, respectively. The root growth of all the test plant species was more sensitive to the extracts than their shoot growth, except alfalfa. The results of the present study indicate that the A. pennata leaf extracts may have allelopathic potential and may contain allelopathic substances. Therefore, further studies are required for isolation and identification of the growth inhibitory substances which are responsible for the allelopathic effect of A. pennata

Evaluation of the Allelopathic Potential of Leaf Extracts from Dischidia imbricata (Blume) Steud. on the Seedling Growth of Six Test Plants

Dischidia imbricata (Blume) Steud. is a herbaceous plant belonging to the Apocynaceae family. This plant has been reported to possess various pharmacological properties, however, there has been no report related to its allelopathic properties. Therefore, the aqueous methanol extracts of D. imbricata were examined for possible allelopathic activity against the seedling growth of dicotyledonous plants; lettuce (Lactuca sativa L.), cress (Lepidium sativum L.), and alfalfa (Medicago sativa L.), and monocotyledonous plants; barnyard grass (Echinochloa crus-galli (L.) P. Beauv.), Italian ryegrass (Lolium multiflorum Lam.), and timothy (Phleum pratense L.). D. imbricata extracts exhibited a significant inhibition on the seedling growth of all the test plant species at the concentration ≥ 0.01 g dry weight equivalent extract mL-1. The seedling growth of lettuce showed the highest inhibition with D. imbricata extracts followed by alfalfa and cress, whereas the least inhibition was found on the seedling growth of timothy. Concentrations required for 50% inhibition (I50 values) of all the test plant species were in the range of 0.003 to 0.067 g D.W. equivalent extract mL-1 for shoot growth, and 0.018 to 0.026 g D.W. equivalent extract mL-1 for root growth. In addition considering the I50 values, the root growth of the test plant species was more sensitive to D. imbricata extracts than their shoot growth, except cress seedling. These results indicated that D. imbricata may possess allelopathic activity and may contain allelopathic substances

Phytotoxic effects of Cerbera manghas L. leaf extracts on seedling elongation of four monocot and four dicot test species

Exploration of allelochemicals with phytotoxic effects is intended to minimize a current dependency on synthetic herbicides in weed management. Several allelochemicals from the tropical tree Cerbera manghas (sea mango) have been reported as termiticides and bactericides. The present study investigated possible phytotoxic effects of C. manghas leaf extracts under laboratory conditions. Four monocots: barnyard grass (Echinochloa crus-galli), foxtail fescue (Vulpia myuros), Italian ryegrass (Lolium multiflorum), and timothy (Phleum pratense) and four dicots: alfalfa (Medicago sativa), garden cress (Lepidium sativum), lettuce (Lactuca sativa), and rapeseed (Brassica napus) were used as test species. Elongation of both shoots and roots of seedlings was measured to assess any phytotoxic effects. The results showed that the sensitivities of shoots and roots were different between the test species, and the inhibition of seedling elongation significantly increased with increasing concentration of leaf extracts of C. manghas for all the test species. The IC50 (50% inhibitory concentration) values showed that 8.50–32.30 and 4.26–34.67 mg dry weight equivalent extract mL−1 of C. manghas inhibited seedling elongation by 50%, for shoots and roots respectively. Isolation and identification of the phytotoxic substances from C. manghas are suggested for future investigation

Phytotoxic property of the invasive plant Tithonia diversifolia and a phytotoxic substance

Tithonia diversifolia (Hermsl.) A. Gray is a perennial invasive plant and spreads quickly in the invasive areas. The extracts of T. diversifolia were found to be toxic to several crop plant species such as rice, maize, sorghum, lettuce and cowpea, and several putative allelopathic substances were identified. However, there is limited information available for the effects of T. diversifolia on wild plants including weed plant species. We investigated the allelopathic potential of T. diversifolia extracts on weed plants, and searched for phytotoxic substances with allelopathic activity. An aqueous methanol extract of T. diversifolia leaves inhibited the growth of weed plants, Lolium multiflorum Lam., Phleum pretense L., Echinochloa crus-galli (L.) Beauv. The extract was then purified by several chromatographic runs and a phytotoxic substance with allelopathic activity was isolated and identified by spectral analysis as tagitinin C. The substance inhibited the growth of Lolium multiflorum, Phleum pratense and Echinochloa crus-galli at concentrations greater than 0.1 – 0.3 mM. The present results suggest that T. diversifolia may possess allelopathic potential on weed plants and tagitinin C may be responsible for the allelopathic effects of T. diversifolia. The allelopathic potential of T. diversifolia may contribute to its invasive characteristics

Isolation and identification of a growth inhibitory substance from Heliotropium indicum L.

Heliotropium indicum L. belongs to the family Boraginaceae. The plant has been used as a folk medicine because it contains substances of various biological activities. It is also identified as a common weed which grows wildly in crop fields in tropical and subtropical regions of the world. However, there is little information on the allelopathic effect in this plant. Therefore, this study was undertaken to investigate the growth inhibitory effect and to identify the growth inhibitory substances in H. indicum. An aqueous methanol extract of H. indicum inhibited shoot and root growth of barnyard grass, foxtail fescue, timothy, cress, lettuce and rapeseed at concentrations higher than 10 mg dry weight equivalent extract/mL. The concentrations required for 50% growth inhibition (I50) of those test plants ranged from 3–282 mg dry weight equivalent extract/mL. The extract was then separated using a sequence of chromatographic fractionations and a growth inhibitory substance was isolated and identified by spectral analysis as methyl caffeate. Methyl caffeate inhibited the growth of lettuce and foxtail fescue at concentrations higher than 1.0 mM. The results suggest that methyl caffeate may contribute to the growth inhibitory effect of H. indicum and may play an important role in the allelopathic effect of H. indicum

The potency of lemon ( Citrus limon L.) essential oil to control some fungal diseases of grapevine wood

This study aimed to evaluate the in vitro antifungal activity (AA) of the essential oil (EO) of lemon (Citrus limon L.) against three pathogenic fungi attacking grapevine wood. The composition of the EO was also studied. Ten volatile components were identified by gas chromatography–mass spectrometry. The results showed that the EO consists of volatile components where monoterpene hydrocarbons are the most abundant ones. Four major components were identified, which represent 99.9% of the total EO (limonene, neral, ß-pinene, and ?-terpinene). The AA of the EO was evaluated against three pathogenic fungi attacking grapevine wood (Eutypa sp., Botryosphaeria dothidea, and Fomitiporia mediterranea). The results showed that the EO exerts AA against all tested fungi and significantly inhibits their growth. Eutypa sp. is the most sensitive fungus. These results show, for the first time, a new use for the EO of lemon (C. limon L.) to control fungal diseases of grapevine wood. Résumé Cette étude examine l’activité antifongique in vitro (AA) de l’huile essentielle (EO) de citron (Citrus limon L.) contre trois champignons pathogènes du bois de la vigne. La composition de l’EO a également été étudiée. Dix composants volatiles ont été identifiés par chromatographie en phase gazeuse–spectrométrie de masse. Les résultats ont montré que l’EO est constituée de composants volatils où les hydrocarbures de monoterpènes sont majoritaires. Quatre composants principaux ont été identifiés, ce qui représente 99,9 % de l’EO totale (limonène, néral, ß-pinène et ?-terpinène). L’AA de l’EO a été évaluée contre trois champignons pathogènes du bois de vigne (Eutypa sp., Botryosphaeria dothidea et Fomitiporia mediterranea). Les résultats ont montré que l’EO exerce une AA contre tous les champignons testés et inhibe de manière significative leur croissance. Eutypa sp. a été le plus sensible. Ces résultats montrent, pour la première fois, une nouvelle utilisation pour l’EO du citron pour lutter contre les maladies fongiques du bois de vigne

Comparative Analyses Define Differences Between Bhd-Associated Renal Tumour and Sporadic Chromophobe Renal Cell Carcinoma

BACKGROUND: Birt-Hogg-Dubé (BHD) syndrome, caused by germline alteration of folliculin (FLCN) gene, develops hybrid oncocytic/chromophobe tumour (HOCT) and chromophobe renal cell carcinoma (ChRCC), whereas sporadic ChRCC does not harbor FLCN alteration. To date, molecular characteristics of these similar histological types of tumours have been incompletely elucidated. METHODS: To elucidate renal tumourigenesis of BHD-associated renal tumours and sporadic renal tumours, we conducted whole genome sequencing (WGS) and RNA-sequencing (RNA-seq) of sixteen BHD-associated renal tumours from nine unrelated BHD patients, twenty-one sporadic ChRCCs and seven sporadic oncocytomas. We then compared somatic mutation profiles with FLCN variants and RNA expression profiles between BHD-associated renal tumours and sporadic renal tumours. FINDINGS: RNA-seq analysis revealed that BHD-associated renal tumours and sporadic renal tumours have totally different expression profiles. Sporadic ChRCCs were clustered into two distinct clusters characterized by L1CAM and FOXI1 expressions, molecular markers for renal tubule subclasses. Increased mitochondrial DNA (mtDNA) copy number with fewer variants was observed in BHD-associated renal tumours compared to sporadic ChRCCs. Cell-of-origin analysis using WGS data demonstrated that BHD-associated renal tumours and sporadic ChRCCs may arise from different cells of origin and second hit FLCN alterations may occur in early third decade of life in BHD patients. INTERPRETATION: These data further our understanding of renal tumourigenesis of these two different types of renal tumours with similar histology. FUNDING: This study was supported by JSPS KAKENHI Grants, RIKEN internal grant, and the Intramural Research Program of the National Institutes of Health (NIH), National Cancer Institute (NCI), Center for Cancer Research

Light-induced structural changes and the site of O=O bond formation in PSII caught by XFEL

Photosystem II (PSII) is a huge membrane-protein complex consisting of 20 different subunits with a total molecular mass of 350 kDa for a monomer. It catalyses light-driven water oxidation at its catalytic centre, the oxygen-evolving complex (OEC). The structure of PSII has been analysed at 1.9 Å resolution by synchrotron radiation X-rays, which revealed that the OEC is a Mn4CaO5 cluster organized in an asymmetric, 'distorted-chair' form. This structure was further analysed with femtosecond X-ray free electron lasers (XFEL), providing the 'radiation damage-free' structure. The mechanism of O=O bond formation, however, remains obscure owing to the lack of intermediate-state structures. Here we describe the structural changes in PSII induced by two-flash illumination at room temperature at a resolution of 2.35 Å using time-resolved serial femtosecond crystallography with an XFEL provided by the SPring-8 ångström compact free-electron laser. An isomorphous difference Fourier map between the two-flash and dark-adapted states revealed two areas of apparent changes: around the QB/non-haem iron and the Mn4CaO5 cluster. The changes around the QB/non-haem iron region reflected the electron and proton transfers induced by the two-flash illumination. In the region around the OEC, a water molecule located 3.5 Å from the Mn4CaO5 cluster disappeared from the map upon two-flash illumination. This reduced the distance between another water molecule and the oxygen atom O4, suggesting that proton transfer also occurred. Importantly, the two-flash-minus-dark isomorphous difference Fourier map showed an apparent positive peak around O5, a unique μ4-oxo-bridge located in the quasi-centre of Mn1 and Mn4 (refs 4,5). This suggests the insertion of a new oxygen atom (O6) close to O5, providing an O=O distance of 1.5 Å between these two oxygen atoms. This provides a mechanism for the O=O bond formation consistent with that proposed previousl