Melissa officinalis is a medicinal plant belonging to Lamiacea family. This plant has been cultivated in many parts of the world due to its therapeutic effects. This study was conducted to improve the antioxidant activities of Melissa officinalis proliferated shoots obtained from tissue culture. The seeds were cultured in MS hormone-free medium in order to obtain seedlings. The shoots were then transferred to MS medium supplemented with 2 mg/ L BAP. Salicylic acid (SA) was added to the medium at concentrations of 0, 50, 100 and 200 µM after 45 days. The antioxidant activity by the methods of free radical scavenging (DPPH), reducing power (RP) and superoxide anion scavenging activity (SO) was measured and the phenolics, flavonoids and rosmarinic acid contents were evaluated in proliferated shoots, 4,7,10 and 14 days after treatment. As a result, the highest free radical scavenging and RP activity, as well as the highest value of total phenolic and rosmarinic acid, were observed in shoots after 14 days of treatment with 100 µM SA. The elevated level of SO activity and total flavonoids were obtained from the shoots treated with 50 µM SA for 14 days. In general, treatment with 100 µM SA for 14 days was proved to be better for the increase of antioxidant activity and the amount of the compounds with recognized antioxidant activity.
With 29 species in Iran, Polygonum L. is comprised of annual and perennial plants in different habitats. P. aviculare makes a species complex, hardly distinguished from P. arenastrum and P. patulum. In the present study, pollen grains, fruit surface and petals and leaves epidermis features were used to provide diagnostic features in order to separate species from one another. In Total, 33 populations of 6 annual species, including P. aviculare, P. arenastrum, P. patulum, P. argyrocoleon, P. polycnemoides and P. olivascens were studied. Specimens were gathered during field trips and studied by means of light and scanning electron microscopes. The Pollen grains of all the species which were studied were monad, subprolate or prolate spheroidal and tricolpate. Main differences were also observed in their surface ornamentations. Length of equatorial and polar axes and colpus, granules diameters and the average distance between granules were other diagnostic features of the pollen grains. Statistical analysis of epidermis features revealed that the length and width of epidermis cells and stomata length varied in the species studied. A close relationship was found between P. aviculare and P. arenastrum on the one hand and P. argyrocoleon and P. olivascens on the other. The separation of P. polycnemoides could be attributed to differences in epidermis features. Results showed that a selected set of these features to be of taxonomic importance.
Lolium (Poaceae) is composed of five species in Iran that are of forage and weed importance. Culm and glume anatomy of grasses is inadequately explored. In the present study culm and glume anatomical structures of 17 population of four Lolium species is considered by use of 16 qualitative and quantitative features to distinguish Lolium species in Iran and to determine their diagnostic value. The culm cross-section showed multilayered hypodermis, ribbed or un-ribbed culm cross-sections, cuticles with different thicknesses, and the cortex with different tissues. Vascular bundles are arranged in two to more rings in the culm anatomy. Glume anatomical observations showed differences in girder attachment to vascular bundles, the outline of the cross-section, and the cortex tissue composition. The multi-variate statistical method based on culm and glume anatomical features showed that L. perenne and L. multiflorum are grouped near each other but there is more mixture between L. persicum and L. rigidum. Our findings are in agreement with the grouping pattern achieved by previous researches on leaf anatomy and lemma and palea micro-morphology of the same species. The molecular study by ISSR also provides support for the present study. The culm and glume anatomy of species studied provides valuable data for taxonomic purposes.
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