فصلنامه زیست شناسی گیاهی ایران
سال دوم شماره 2 (پیاپی 4، تابستان 1389)

Salicylic acid is an endogenous plant growth regulator. It is involved in various physiological processes of plant growth and development and plays an active role in plant defense responses. In this study, because of the economic, medicinal and dietary importance of lepidium sativum, we studied some effects of salicylic acid with different concentrations (0, 0.01, 0.05, 0.1 mM) on some of the growth factors and biochemistry. Studies showed that shoot and root length increased significantly in plants which were pretreated with salicylic acid (0.01, 0.05, 0.1 mM). In addition, content of H2O2 was increased significantly in (0.05 and 0.01 Mm) of salicylic acid as compared with the control. Treatment with 0.01 mM of salicylic acid increased Mn +2 and Zn +2 absorptions while 0.01, 0.05 and 0.1 Mm of salicylic acid decreased anthocyanin and carotenoid contents in compare with control. Treatment with 0.05 and 0.1 mM of salicylic acid decreased catalase activity and malondialdehyde content as compared with control.

Floral development in Bougainvillea spectabilis Willd., (Nyctanginaceae), together with the horticultural, pharmaceutical and agroforestry importance, is not yet well understood. The hermaphroditic and apetalous flowers of B. spectabilis have a 5-lobed tubular perianth, eight stamens with unequal filaments and one carpel. Epiphylly, phyllotaxis and placentation are all important morphological problems in the flowers of this species. To understand these problems better, a detailed study on floral organogeny in the species was first completed using epi illumination light microscopy. Our results revealed that organs of one flower develop regularly from the outer to the inner. Tepals, were the first organs which appeared helically in the margins of floral meristem. Soon after, eight stamens arised sequentially in a 3/8 spiral. Finally, the gynoecial wall was produced by the peripheral growth of the floral apex and then, the single ovule was formed from the gradual upgrowth and transformation of the floral apex. Our results showed that epiphylly was a result of cellular fusion between the base of the floral bud and subtended bract in B. spectabilis, which occured when floral development was completed.

Peroxidase is one of the most important enzymes with many important functions in plant’s defense system. In this study, the response of peroxidase to infection by Aspergillus niger was investigated. In order to measure the enzyme activity, ahmadaghaii pistachio nuts (P. vera L.) were infected with Aspergillus niger and then they were cultured in sterile vermiculite medium. Peroxidase was then extracted in phosphate buffer and precipitated by amonium sulfate. The enzyme activity was then assessed spectrophotometrically and by Polyacrylamide Gel Electrophoresis (PAGE). The results showed that the activity of peroxidase was higher in infected seedlings compared to uninfected samples.=

Soybean (Glycine max (L.) Merr.) is a thermophilic plant. But the temperature up to 40°C inhibits its seed germination. In this research, the role of exogenous polyamines (putrescine, spermidine and spermine) in the heat-shock protection of soybean seedlings c.v Sahar was investigated. Also effects of pretreatment of polyamine inhibitor, on seedling growth were monitored. Results showed that exposure to heat-shock decreased growth whereas application of putrescine and spermidine increased thermo-tolerance and growth recovery. Similarly, lysine, an amino acid, was tested at equivalent concentration to demonstrate that heat- shock protection is really a polyamine phenomenon and not simply a growth effect from a source of nitrogen. The results showed that, polyamines did not act merely as a source of nitrogen when stimulating growth, suggesting stress adaptive role of polyamines. Pretreatment of polyamines plus biosynthetic inhibitors reduced the inhibitory effects and enhance growth recovery.

Rooted cuttings of lisianthus (Eustoma grandiflora L.) were treated with aluminum as AlCl3 to a final concentration of 0.88 mM at a constant pH of 4.5 for 96 hours. Significant increases were observed in the activities of superoxide dismutase, catalase, and ascorbate peroxidase of roots of Al-treated plants as compared to those of the corresponding control plants. The activity of peroxidases and the level of peroxidation of membrane lipids of the aluminum -treated plants were significantly lower than those of the control plants. About 40% of supplied aluminum was absorbed by lisianthus plants during 96 h treatment. The results suggested that not only aluminum did not have any detrimental effects on lisianthus roots but also it triggered the activation of enzymatic antioxidant system of the plant. Therefore, Al can be introduced as a beneficial element for the growth of lisianthus plant.

Solanaceous plant, Datura innoxia, has valuable tropane alkaloids pharmaceutical effects. In this study, seed zygotic embryos were cultured in vitro and plantlets were produced and explants with single internodes and two auxiliary buds from the produced plantlets were cultured in B5 medium with different concentrations of IAA (0.5, 1, 1.5, 2 mg/L), NAA (0.5, 1, 1.5, 2 mg/L) and BA (0.5, 1, 1.5 mg/L) to investigate the effects of the growth regulators on callus production, organogenesis and total alkaloid contents. Concentrations of the last two hormones were used reciprocally. Total alkaloid concentrations of calli were identified by UV spectrophotometer at 258 nm and callus total alkaloid contents and were compared with the content of plantlets. Results showed that, in the presence of both NAA and BA, explants formed callus and increase of NAA concentrations, in turn, increased callus weights and total alkaloid contents as well. IAA had no significant effect on callus and organ induction. Comparison of total alkaloid contents of calli with shoots and roots of Datura innoxia plantlets in hormone free B5 medium, showed that the alkaloid contents of calli were lower than differentiated tissues in hormone free B5 medium, but the use of NAA and BA hormones caused an increase in alkaloid contents of calli as compared with in vitro cultured organs.

Astragalus is the largest genus of vascular plants. This genus has 2500-3000 species and 250 sections. In regard to economic and medicinal importance of Astragalus genus, this study, was carried out to determine and to distinguish of intraspecific diversity in phenolic components of Astragalus verus in the west of Iran. For this reason, leave phenolic components belonging to 20 different stations were extracted and analyzed by TLC (Thin Layer Chromatography), to examine the presence or absence of three flavonoidic standards, such as flavones, quercetine and rutin. Finally, data of flavonoid studies were analyzed by MVSP (Multivariate Statistical Package) and SPSS (Statistical Package for the Social Science) softwares with WARD, PCA (Principle Component Analysis) and UPGMA (Unweighted Pair Group Method with Arithmetic mean) methods. Results of flavonoid studies showed intraspecific diversity in chemical components (chemotype) level. The results showed different phenolic groups of Astragalus verus from different stations with different ecological conditions. The studied ecological factors included soil texture, pH, EC, elevation, latitude and longitude. Ecological data analysis showed that, among studied ecological factors, elevation from sea level has the most important role in observed intraspecisic diversity of Astragalus verus in the west of Iran.