The progress of nanotechnology presents many nanoparticles that are important in medicine, agriculture and industry. Quickly and entirely absorbed by plants, nano-compounds and remedy their nutrient deficiency and satisfy this need. Iron oxide nanoparticles with suitable surface chemistry can be used as a rich source of iron for plants due to its gradual release of Fe in a wide pH range (pH 3 to 11). The present study investigated the impact of iron oxide nanoparticles (Fe 2 O 3 NPs in 0, 10, 20 and 30 µM concentrations) on physiological parameters of peppermint (Mentha piperita) under salt stress (0, 50, 100 and 150 mM concentrations of NaCl). Fe 2 O 3 NPs caused increases in leaf fresh weight and dry weight, phosphorus, potassium, iron, zinc, and calcium contents of the peppermint under salinity stress but did not have an effect on the sodium element. 30 µM concentration of Fe 2 O 3 NP was more impressive. Lipid peroxidation and proline contents of the peppermint under salinity decreased significantly by applying Fe 2 O 3 NPs. The maximum activities of total antioxidant enzymes (I %), catalase, superoxide dismutase, and guailcol peroxidase were observed in plants treated with 150 mM of NaCl, but application of Fe 2 O 3 NPs declined these antioxidant activities. The results suggest that the appropriate concentration of iron nanoparticles could be used for stress resistance of the peppermint.

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Abstract. Yarmoohammadi M, Talebi SM, Nohooji MG. 2017. Infraspecific variations in essential oil and glandular trichomes in Nepeta heliotropifolia. Biodiversitas 18: 964-970. Nepeta heliotropifolia Lam. (Labiatae) is one of the perennial medicinal and aromatic plants, naturally grows in different regions of Iran. The essential oil composition of aerial parts and also the micromorphology and distribution of foliar trichomes of N. heliotropifolia from two different regions of Iran were studied. The extracted essential oils were significantly composed of caryophyllene oxide and phytol, which were quantified by GC and identified based on their GC/MS spectra. The essential oil compositions differed greatly with habitat as well as former investigations. Phytol was quantified between 0.75-10. 29% of the total essential oil, but caryophyllene oxide was quantified between 3.90-12.17% of the total essential oil. Trichomes investigations showed that leaves bear an indumentum of glandular and non-glandular hairs. Two main kinds of glandular trichomes were observed; peltate and capitate. The numbers of capitate and peltate trichomes varied between populations. Such great differences in the essential oil composition may be attributed to chemotype creation and also an adaptation of these populations to particular habitats.

In the current study, the trichome density and the chemical variation of the hydrodistillated essential oils were determined along the altitudinal gradient in Nepeta sessilifolia, N. heliotropifolia, and N. fissa. The capitate glandular trichomes were predominant in all populations studied. Denser leaves indumentum was observed in high altitude populations of N. heliotropifolia, and in low altitude populations of N. sessilifolia and N. fissa. Moreover, the inter-population chemical polymorphism was detected. In the lower population of N. sessilifolia, spathulenol (14.2%) was the major compound of essential oils. This oil had great amount of oxygenated sesquiterpene (35.3%), while the oil of high altitude population had great amount of diterpenes, namely phytol (32.8%). In N. fissa, the main compound in lower population was β-caryophyllene (33.1%), whereas in the higher population it was caryophyllene oxide (21.5%). In N. heliotropifolia, 1,8-cineole (20.1%) was as the principal oil compound in low altitude population and β-caryophyllene (18.8%) in the high altitude population. We suggested that the amount of different types of monoterpenes decreases along the altitudinal gradient and the amount of oxygenated compounds increases with the elevation.

Nepeta are widely distributed worldwide and in different parts of Iran where seventy-nine species were registered. The essential oil of these aromatic plants, which accumulates and secrets by trichomes, has been used in medicinal and industrial products. In addition, these epidermal structures can be used as taxonomic traits. We examined the morphology and density of leaves trichomes of twelve Nepeta species using the light and scanning electron microscopes. Three types of indumentum are found in these species, which composed of two main types of glandular: peltate and capitate, and nonglandular; branched and unbranched trichomes. The number of the observed hairs differed between the studied species and analyses of variant test (ANOVA) showed significant variations among some of them. CA-joined plot proved that trichomes could be used as distinguishing characteristic. Therefore, we suggested that the type of indumentum and the most abundant glandular and non-glandular trichomes have high taxonomic value in species identification within the genus.