Assessment of Allelopathic Potential of Senna garrettiana Leaves and Identification of Potent Phytotoxic Substances

Senna garrettiana (Craib) Irwin & Barneby (Fabaceae) is a medicinal plant known to be rich in biologically active compounds that could be exploited to produce bioherbicides. The present study was conducted to explore the allelopathic potential and phytotoxic substances of S. garrettiana. Extracts of S. garrettiana leaves were found to significantly inhibit the growth of Lepidium sativum L. and Echinochloa crus-galli (L.) P. Beauv. (p ≤ 0.05). The phytotoxic substances were isolated and identified as vanillic acid and ferulic acid by bioassay-directed fractionation and spectral data analysis. The two compounds were shown to significantly inhibit the seed germination, seedling growth, and dry biomass of L. sativum. Based on the concentration required for 50% growth inhibition (defined as IC50), the roots of L. sativum were the most sensitive to the compounds, and the inhibitory effect of ferulic acid (IC50 = 0.62 mM) was >1.3 times more potent than that of vanillic acid (IC50 = 0.82 mM). In addition, a mixture of the two compounds (0.3 mM) resulted in synergistic inhibitory activity against the L. sativum roots compared with the individual compounds. These results suggest that the extracts of S. garrettiana leaves and their phytotoxic compounds have potential as candidate natural herbicides.

Allelopathy and Allelopathic Substances of Fossil Tree Species Metasequoia glyptostroboides

Metasequoia glyptostroboides Hu et W.C. Cheng is one of the oldest living conifer species, and it has remained unchanged for millions of years compared to its fossils from the Cretaceous period. The species are cultivated in the parks, gardens, and roadsides in many countries. We investigated the allelopathy and allelopathic substances in fallen leaves of M. glyptostroboides. An aqueous methanol extract of the fallen leaves inhibited the growth of cress (Lepidium sativum L.), lettuce (Lactuca sativa L.), alfalfa (Medicago sativa L.), Lolium multiflorum Lam., Phleum pretense L., and Vulpia myuros (L.) C.C.Gmel. The extract was then purified by several chromatographic steps, and two allelopathic substances were isolated and determined by spectral data to be (+)-rhododendrol and 9-epi-blumenol C. The compound inhibited the growth of cress and L. multiflorum. M. glyptostroboides is a deciduous perennial tree, and accumulation of its fallen leaves occur on the soil under the trees. Therefore, those allelopathic substances in the fallen leaves may be liberated into the rhizosphere soil during the decomposition process of fallen leaves and provide a competitive advantage for M. glyptostrob through the growth inhibition of competing plant species nearby. Therefore, M. glyptostroboides is allelopathic, and (+)-rhododendrol and 9-epi-blumenol C may be contribute to the allelopathy.

Improving the Effects of Salt Stress by β -carotene and Gallic Acid Using Increasing Antioxidant Activity and Regulating Ion Uptake in Lepidium Sativum L.

Background: Plant growth, physiological and biochemical processes are severely affected by soil salinity. In the present study, toward investigating the interaction of antioxidants and salt stress in Lepidium sativum seedlings, two antioxidants (β-carotene and gallic acid) were sprayed on the plants. Results: The findings revealed that total dry and fresh weight were adversely affected by 25 mM NaCl salinity stress. Moreover, K+ content decreased while Na+ content increased significantly. The application of β-carotene and gallic acid significantly improved tolerance to salt stress by regulating ion uptake, reducing H2O2 and malondialdehyde (MDA) content, as well as increasing enzymatic antioxidant activity and phenolic, glutathione, and chlorophyll content. Conclusions: Our findings are indicative of β-carotene and gallic acid in the induction of salt tolerance in economically important crops.

Phenetic phytoindication and biotesting of soils in recreation zones of Tver city

Исследованы фенофонды ценопопуляций подорожника большого (Plantago major L.) и сныти обыкновенной (Aegopodium podagraria L.) в рекреационных зонах г. Твери с разным уровнем загрязнения почв тяжелыми металлами (ТМ). Параллельно проведено биотестирование почв модельных биотопов по параметрам развития семян тест-растений - горчицы белой (Sinapis alba L.), кресс-салата (Lepidium sativum L.), сорго черного (Sorghum nigrum L.) в соответствии с ГОСТ Р ИСО 18763-2019. По мере возрастания суммарной токсической нагрузки на биотопы среднее число фенов у сныти и подорожника снижается. Однако доля редких фенов у сныти возрастает, а у подорожника уменьшается. Общие показатели фенетического разнообразия (среднее число и доля редких фенов) у сныти коррелируют с суммарной токсической нагрузкой на почвы в большей степени, чем у подорожника. Параметры развития семян разных видов тест-растений неоднозначно отражают фитотоксичность почв. В большей степени с суммарным содержанием ТМ в почве коррелируют показатели всхожести семян и размеры корней проростков у горчицы. Данные по фитоиндикации биотопов на основе фенетических показателей ценопопуляций сныти и, в меньшей степени подорожника, в целом согласуются с результатами биотестирования почв. The phenofonds of Plantago major L. and Aegopodium podagraria L. cenopopulations in recreation zones of Tver with different levels of soil contamination with heavy metals (HM) were studied. In parallel, biotesting of soils of model biotopes was carried out according to the parameters of test plants seeds development - Sinapis alba L., Lepidium sativum L., Sorghum nigrum L. in accordance with ISO 18763:2016. With an increase in the total toxic load on biotopes, the average number of phenes in P. major and A. podagraria decreases. However, the share of rare phenes increases in A. podagraria, and decreases in P. major. The general indicators of phenetic diversity (average number and proportion of rare phenes) in A. podagraria correlate with the total toxic load on soils to a greater extent than in P. major. The development parameters of seeds of different species of test plants ambiguously reflect the phytotoxicity of soils. To a greater extent, the indicators of seed germination and the seedlings root size in S. alba correlate with the total content of HM in the soil. The data on the phytoindication of biotopes based on the phenetic indices of the cenopopulations of A. podagraria and, to a lesser extent, P. major, are generally consistent with the results of soil biotesting.

Antioxidants from Callus Technology

Antioxidants are very important compounds that are very vital in human health and they have been proven to reduce the risk of diseases such as cancer in human health. Many researchers have used callus to produce antioxidant and most of them used different techniques to get reasonable amounts of antioxidants. The technique used determines the number of antioxidants that will be produced from any explants. Callus Technology involves the techniques of producing callus and metabolites in the presence of explants using different plant hormonal combination in media, different environmental culture condition (light, relative humidity and tempreture), use of elicitors and under a sterile conditions. Callus technology is very promising due to its ability to produce a larger quantity of metabolites (antioxidants) compare to the raw extract of its explants. The use of callus to produce antioxidants is very important and very useful in discovering new plants as a source of antioxidants. The use of callus technology was reviewed for production of antioxidant from the callus of the following plants: Sericostoma pauciflorum, Helicteres angustifolia L, Lepidium sativum L, Randia echinocarpa, Andrographis paniculata Nees, Citrullus colocynthis, Rauwolfia vomitoria Afzel, Decalepis hamiltonii, Bacopa monnieri (Linn.) and Isodon rugosus (Wall. Ex Benth). Callus technology can be utilized to produce antioxidants and other metabolites in industrial quantity. Most of the metabolites from plants have been found to have medicinal values or useful to mankind and antioxidant is one of them.