Journal of Plant Biological Sciences
Year:2012 | Volume:4 | Issue:11|Papers Count:7

The Region of Yahya Abad is located at the Southern slops of Karkas Mountains with about area of 6000 hectare, at 35 kilometres southwest of Natanz. The lowest altitude of this region is 2000 m and the highest altitude is 2720 m. The average annual precipitation is 147.22 mm and means annual temperature is 15.41oC. The overall plants of the area constituted 190 species belonging to 31 families and 129 genera. A total of 18 genera (62%) and 23 species (12%) belonged to monocotyledons, 111 genera (86%) and 167 species (88%) to dicotyledons. The most families were Asteraceae (36 species), Poaceae (23 species), Fabaceae (19 species), Brassicaceae (18 species), Lamiaceae (17 species), Caryophyllaceae (12 species) and Rubiaceae (5 species). Study of chorology indicated that the most plants were the Irano-Turanian floral elements (71.1%) and Irano-Turan-Euro-Sieberian floral elements (14.4%), among which 35 species were endemic of Iran. In this research, hemicryptophytes (44.7%), therophytes (29%), chamaephytes (18.4%), geophytes (6.3%) and phanerophytes (1.6%) made up the most important life forms, respectively.

Podophyllotoxin (PTOX) is a lignan compound which occurs in a few plant species and has pharmacological significance for its anticancer activities. Linum album, one of endemic species in Iran, has PTOX and other lignans. Chitin and Chitosan are the main compounds of fungal species and as biotic elicitors could be used to improve secondary metabolites. In this study, we investigated the different concentration effects of chitin and chitosan on cell growth, PTOX and lariciresinol production in l. album cell culture. Next, we evaluated the effecr of optimal concentration of chitosan on lignan, phenol, flavonoid, flavonol and lignin content at different times. Treatment of L. album cell cultures with the 100 mg/L chitosan increased the production of PTOX and lariciresinol about two times higher than contol.In addition, Chitosan increased phenol, flavonoid and flavonol. Lignin was increased 2-fold higher than the control in response to chitosan. To study mechanism of chitosan action, phenylalanine ammonio-lyase (PAL) and cinnamyl alcohol dehydrogenase (CAD) activity were investigated. The activity of PAL and CAD enzymes involved in the first steps of the PTOX biosynthesis was activated by chitosan, reaching a peak within three days after treatment. Chitosan regulated the production of PTOX, lariciresinol and phenylpropanoid compounds by effecting on enzymes activity through PTOX biosynthesis pathway.

The effect of methyl jasmonate on some morphological characters and flower yield of chamomile under salt stress was evaluated under greenhouse conditions. The experimental design was as factorial based on a randomized complete block design (RCBD) with three replications. In this research, methyl jasmonate (MeJA) sprayed at five levels including, 0 (without spraying or control treatment), 75, 150, 225 and 300 µM and also salt stress applied at four levels including 2.1 (without adding salt), 6, 10 and 14 dS/m by adding NaCl to each pot. MeJA sprayed at three growth stages: a) 3 to 4 leaves, b) stem elongation and c) flowering (anthesis). Results showed that spraying with MeJA and salinity had significant effects (P≤0.05) on all measured traits. The highest leaf area, root and shoot weight and flower yield, and the lowest, specific leaf weight and root length were obtained in 75 µM and 6 and 14 dS/m salted treatments, respectively. In this treatments root and shoot weight increased significantly. Shoot weight in other treatments of MeJA showed values that equal with control treatments. In treatments with higher than 75 µM MeJA, resulted in a reduction of root weight. However, root weight in plants which treated with MeJA, in all salt levels was higher than control treatment. It seemed that chamomile might have an enhancement effect on its growth at mild salinity conditions. There was a positive correlation between leaf area and flower yield. Therefore, treatments or conditions that induced expansion of leaf area could increase flowers yield. Results showed that methyl jasmonate enhanced flower yield both in normal and salt stress conditions.

Dehydrins are known as late-embryogenesis abundant (LEA) proteins Group II, which are accumulated during low-temperature or water-deficit conditions. They are asumed to play a role in freezing and drought-tolerance in plants. In order to study the impact of dehydrins in response of tolerant and sensitive genotypes to drought, one experiment was carried out in a factorial design based on CRD for a wild ecotype and two barley cultivars in greenhouse. The barley cultivars including Yusef (HV1) and Morocco (HV2) and wild ecotype (HS) were as the first factor and irrigation treatment with three levels consisted of normal (70% of water holding capacity of soil), mild stress (30%) and severe stress (10%) was as the second factor. Normal irrigation was continued in two leaf stage and then discontinued for plants under stress to achieve certain level of stress. The samples were collected from the expanded leaves in vegetative stage for physiological and molecular analysis. Analysis of variance for physiological characteristics showed that the effect of water stress on all traits and differences between genotypes were significant, and HV2 had significantly lower dry mater production and relative water content than the other genotypes. Based on the real time PCR results, among 13 barley dehydrin genes, except for Dhn8 and Dhn13, expression of other genes significantly upregulated under severe drought condition. The expression level of Dhn3, Dhn7, Dhn9 and Dhn10 was increased in the tolerant genotypes, HV1 and HS, whereas the expression level of Dhn1 and the other genes increased only in Yusof and HS, respectively that was indicative of the role of dehydrin genes in drought tolerance. The increase of Dhn12 expression level in wild ecotype through drought condition is reported for the first time in the current study.

The objective of the study was to develop an efficient method for shoot regeneration and Agrobacterium-mediated gene transformation into Brasica napus cultivars, Hyola308 and RGS003. Different concentrations of benzylaminopurine (BAP) (3.5, 4, 4.5, 5, 5.5 and 6 mg/L) were evaluated for shoot regeneration of petiol cotyledonary explants. Also, the effect of preconditioning and co-cultivation periods and acetosyringone concentrations were studied on the Gus reporter gene transformation. The experimental design was factorial based on completely randomized design with 3-5 replications. Maximum shoot regeneration was obtained using 3.5 mg/L BAP with 112% for Hyola308 and 120% for RGS003 cultivars. The transformed plants were screened on kanamycin containing medium and the presence and the expression of the reporter gene were confirmed by PCR and Gus assay, respectively. The highest effect on transformation efficiency was observed through 48 h preconditioning and co-cultivation period and 100 µM acetosyringone for Hyola308 (33%), and 38 h preconditioning period, 72 h co-cultivation period and 50 µM acetosyringone for RGS003 (38%).

During the recent years, unicellular algae have been considered as an important source of unsaturated fatty acids, carotenoids such as beta-carotene and food and drug supplementaries. These algae also play important role as live food in breeding of zooplankton, molluscs and aquatic animals in larval stage. So far many species of different families and generas of unicellular algae have been rightly introduced for aquaculture industry. The family of Scenedesmaceae is known as one of the important microalgae which belong to Chlorophyceae class. This family is identified with several generas which are all important in aquaculture industry for Artemia, Daphnia and Rotifer breeding. In this research, in order to obtain laboratory demands of unicellular algae, one the most important fresh water sources of west Azerbaijan province, Mahabad Dam Lake was investigated. This study consisted of morphologic, molecular and nutrition value which resulted in isolation of two species of Scenedesmus obliquus, Kützing 1833 and Desmodesmus cuneatus, Hegewald 2002 of this family. The study of mass and batch culturing potential and also the fatty acid profile of these species revealed efficiency of these species for aquaculture industry. However, in spite of morphologic similarities of the two, the total fatty acids of Desmodesmus cuneatus was found significantly higher than other species (P<0.05).

Chromium (Cr) is a highly toxic heavy metal for microorganisms, animals and plants. Due to its widespread industrial use, it has become a serious pollutant in a diverse array of environments. Excess Cr is a stressful factor for plants that can limit their growth. It can also induce oxidative stress in plants. In this research, four-week sunflowers which were grown under controlled greenhouse conditions, were exposed to various concentrations of Cr (0.0, 0.001, 0.01, 0.1. 1.0, 5.0, 10.0 mM) to determine how chromium would affect the growth and oxidative stress induction in the root part of sunflower. The field survey showed that 5 and 10 mM concentrations of Cr led to lowering growth parameters (such as; length, fresh and dry weigh) in sunflower's roots. However, the lower concentrations showed no significant differences compared to the control. In contrast, the content of malondialdehyde as the oxidative stress indicator, increased in this two high level chromium. In addition, chromium treated sunflower roots showed increased proloine contents in 5 and 10mM concentrations. In contrast, protein content reduced in 0.001 mM consentration of chromium compared to the control. However, reduced ascorbate contents in roots occurred with the increase in dehydroascorbate and total ascorbate amount under 1, 5 and 10 mM concentration of Cr treatment. Despite some stress symptoms, sunflower roots accumulated high amount of chromium, and it seemed that chelation and compartmentation of Cr in the roots was a tolerant mechanism for sunflower which occurred under chromium stress.