Iranian Journal of Rangelands and Forests Plant Breeding and Genetic Research
Year:2012 | Volume:19 | Issue:2 (38)|Papers Count:16

Delta-6 desaturase (D6D), an enzyme of a lipid methabolic pathway, has been found as active form in some microorganisms and plants like different species of the genus Echium from family Boraginaceae. The enzyme converts essential fatty acids linoleic acid and a-linolenic acid into long-chain polyunsaturated ones, g-linolenic acid and stearidonic acid, respectively. In this research, to isolate the d6d gene from Iranian borage (Echium amoenum), we followed total RNA isolation from immature seeds, total cDNA synthesis and PCR amplification using the gene specific primers designed according to the sequence of d6d in the other Echium species.Approximately a 1350 bp amplified fragment was inserted into the vector p Bluscript SK (+) and cloned in Escherichia coli strain DH5 a. Nucleic acid sequence analysis of the cloned fragment verified the successful isolation and cloning of the full length CDS of d6d gene from E.amoenum. The cloned CDS include 1347 nucleotides coding for 448 amino acids. The translated protein possessed high similarity of 94–96% to its counterparts previously reported in other Echium species. All the expected domains, i.e., cytochrome b5, fatty acid desaturase, HPGG motif and histidine rich conserved motifs were found in the sequence of translated protein. Furthermore, secondary structure, transmembrane domains and the hydropathy profile of the protein were highly similar to its counterparts in the other Echium species. The d6d gene is a promising gene to engineer the fatty acid metabolism in crop plants. Gene expression studies are necessary for further characterization of the cloned gene and its encoded enzyme.The sequence of the coding region of d6d gene from E. amoenum was submitted to Gen Bank under the accession number GU237486.

With regard to the trend of plant germplasm degradation in our country, as one of the richest countries on plant genetic resources, it is necessary to act fundamentally on conservation and maintenance of available genetic diversity. Using seed cryopreservation, as one of the Ex situ plant germplasm conservation method we can store seed for long-term, with much lower costs and without losing seed viability. In this study the effect of cryopreservation on germination and growth indices (germination percent, germination rate, seed vigour index, plantlet length, plantlet fresh weight) on orthodox seeds of seven plant species (Artemisia khorassanica, Hypericum perforatum, Origanum spp, Trigonella monantha, Phytolacca americana, Hypericum androsaemum, Datura innoxia) in two storage conditions of freezer (-20oC) and cryopreservation (-196oC) were evaluated for two months. Comparing cryopreservation and freezer treatments on each species based on t- student method, no significant differences were observed on germination and growth indices except for germination percent and germination rate. Cryopreservation may be recommended as a suitable and alternative method for healthy long term storage of orthodox seeds in germplasm resources conservation centers.

In order to study yield and physiological traits of five annual medic species namely M.rigidula, M. turbinata, M. orbicularis, M. radiata and M. minima under irrigated conditions, a field study was conducted based on a complete randomized block design with three replications in Islamabad-Gharb station, Kermanshah, Iran. Water requirement estimated by Penman-Monetith method and CROPWAT package using local climatological data based on 90% of irrigation efficiency. Data analysis showed a significant difference (P<0.05) between the species for leaf water content, relative water content, growth period, forage yield and plant height traits. In contrast, there were no significance differences for leaf stem ratio, stems per plant and chlorophyll fluoresce.M. rigidula showed better performance for majority of the traits, especially forage yield, followed by, M. orbicularis and M. minima. M. turbinata and M. radiatahad lowest forage yield and field performance. Cluster analysis of the data by Ward method confirmed results of the data analysis. There was a positive significant correlation coefficient between relative water content and growth period with forage yield at 1% probability. Plant height and chlorophyll fluoresce showed positive and significant correlation with forage yield at 5% probability. Finally, according to the results, M. rigidula is recommendable for forage production under irrigated condition of the province.

Thymusas a member of the Lamiaceae family, is a prennial plant and a very important medicinal plant. For studying of chromosomes morphology inThymus, the seeds of 5 populations, representing 4 species, namely, T. lancifolius, T. daenensis sub sp. daenensis (2 samples), T. fedtschenkoi and T. pubescens were prepared. Mitotic chromosomes were studied in meristematic cells of root tips obtained from germinated seeds. The basic chromosome number was X=15 in all of the populations, but their ploidy level varied and karyotypic formula of T. lancifolius was 25m+5sm (2n=2x=30), T. daenensis sub sp. Daenensis were 22m+8sm and 30m, T. fedtschenkoi was 23m+7sm and T. pubescens was 30m. Based on intra-asymmetry chromosome index, T. daenensis sub sp. daenensis had the most asymmetric and evolutionary karyotypes and T. pubescens had the most symmetric karyotypes. Analysis of variance based on an unbalanced completely randomized design showed a significant difference (P<0.01) among the populations for all of the traits. Cluster analysis classified the populations into two groups.T. daenensiswas classified to first class, T. fedtschenkoi and T. pubescens allocated to the second class.

Karyological characteristics variation inTripleurospermum and Matricaria genera, collected from various locations of Iran, was investigated.a-bromonaphthalene was used for pretreatment, Lewitsky solution for fixation, 1N NaOH for hydrolysis and finally, aceto ironhematoxylin for staining stage. Detailed karyotype features, i.e. total chromosome length (TL), intrachromosomal asymmetry (A1) and interchromosomal asymmetry (A2), total form percent (TF%), asymmetry index (AI) and formula karyotype showed the population were either diploid or tetraploid.T. diciforme from Zabol had symmetric karyotype and a population of M. recutita from Hungary had asymmetric karyotype. The largest chromosome belonged to M. recutita from Isfahan and the smallest chromosome belonged to M. recutita from Hungary. Cluster analysis based on cytogenetic data showed one group containing diploid populations and other group containing tetraploid populations. On the basis of cluster analysis, T. disciforme from Tehran and M. recutita from Zabol had the highest similarity and T. sevanese from Fars and T. disciforme from Zabol had the lowest similarity. Result of principal components analysis showed that more than 89.48 percentages of total variation was justified by the first three factors.

Sorbus aucupariais an important slow growing forest tree with medicinal, industrial, and ornamental uses which is used for reforestation in high altitudes of mountainous areas. The species was endangered at northern forests of Iran. Therefore, micropropagation of adult trees through bud culture can help in conservation purposes of the species. For investigation of micropropagation of the species, apical and lateral buds from micro-cutting shoots of the adult trees were collected from Farim and Sangdeh, Sari Province. Pretreatments of sterilizing were cleaning and brushing of the buds with detergent and ethanol 70% solution and then dipping in 0.2 % fungicide of Tyram for 24 hours. Cleaning of buds with % 0.1 HgCl2 solution for 7 minutes for the samples of the end of fall season was the best treatment. The best medium for shoot regeneration was DKW medium with BA (0.5 mg/l), IBA (0.01 mg/l) and TDZ (0.05 mg/l). Lateral buds culture from shoot cutting was relatively successful in MS medium mixed with vermiculite. Pre-treatment for rooting of shoots was done in free hormone medium and rooting of shoots was done in modified MCM medium supplemented with 1 mg/l of IBA in dark treatment. The plantlets were successfully acclimated in green house.

Morphological variation gives us a knowing perspective, lets us more precisely speculate about genetic diversity among Christ' s-thorn individuals, leads us to identify and select elite germplasms for breeding purposes. On the other hand, biodiversity, itself, draws more attention by farmers, breeders, and conservation experts though such investigations. Plant organs/parts, e.g. leaf and fruit were sampled in three well known habitats: both qualitative and quantitative characteristics were measured. A completely randomized design experiment was carried out with10 replications In situ traits of studied trees were recorded. ANOVA revealed high significance of all measured characteristics indicating a large-scale diversity among the genotypes. For instance, fruit weight ranged 0.5-15gr. Leaf ranged 2-6.7 cm and 10-25% of total solution of the fruit samples comprised solute solids. Certain economic/taxonomically important traits were negatively-or positively correlated. The genotypes were clustered, plot analysis was performed for their morph and origins based on which they were finally grouped. Indian genotypes Collected from Hormozgan were clearly segregated from their Iranian counterparts. Collected genotypes in three provinces showed considerable morphological variations.

In order to investigate the genetic diversity within and between populations of Populus caspicaBornm. based on peroxidase enzyme and morphological leaf traits markers, sampling of thirty trees with over one hundred meter distance were selected in three sub mountain forest habitats (Neka, Golestan, Marzanabad). Two-year old branches were taken on trees crown to investigate quantitative and qualitative peroxidase enzyme activities. Thirteen leaf traits were also recorded in morphological study. Quantitative study of peroxidase using UV Spectrophotometer and qualitative studies were performed by polyacrilamide gel electrophoresis (PAGE). Results showed that the number of main serration of leaf, petiole length, leaf dry matter, angle between the main vein and the second vein and the distance down the most broad leaf area to rule leaf were efficient treats for morphological diversity investigation of the species. By quantitative method, the highest and the lowest activity were related to Marzanabad and Neka, respectively. The qualitative results of the enzyme peroxidase showed the most variation within population in Golestan (15 ha) and lowest in Neka habitat (14 ha). Classification of isoenzyme bands and morphological traits showed high genetic differentiation of several genetic classes within and between the populations for the species.Whereas, three ecotypes of Neka, Golestan and Marzanabad were distinguished. However, peroxidase isoenzyme markers showed more efficient to ecotype differentiation. Also, peroxidase band patterns and morphological marker between male and female individuals didn’t show any differences within the populations.

Regarding to the importance of Eucalyptus as a pioneer and fast growing species in forest plantation, this research was performed to test the effects of chilling stress on seedlings of E. saligna, E. camaldulensis and E. rubida. The activities of perixidase enzyme were determined in leaves of the species exposed to chilling stress. Temperature treatments were -20, 5, and 24°C and green house condition was considered as control. The samples enzymes were extracted immediately and peroxidase was quantitatively and qualitatively studied. Quantitative studies were accomplished by spectrophotometry (in 530 NM Wave Length) and qualitative studies were performed by polyacrylamid gel electrophoresis (PAGE). Results showed that chilling stress altered the activity of peroxidase in leaves, compared to the control. Also, the enzyme altered in different manners dependent upon several factors, such as plant species, tolerance, or sensitivity to stress, and duration of stress. All of these results seemed to indicate that peroxidase is an important component in a plant's response to stress and that they played a significant role in counteracting chilling stress.

In order to compare the yield and herbage quality, 24 accessions of Agropyron trichophorum were surveyed under dry land farming conditions, in a random complete block design with three replications. Some morphological traits and chemical traits of each accession were recorded. The highest value of genetic coefficient of variation and broadsense heritability was obtained for triats of flag leaf length, number of shoot per plant and dry weight and the lowest value was observed for traits of acid detergent fiber and digestibility dry mates. Triats of flag leaf length, spike length, number of shoot per plant, forage yield and water soluble carbohydrate had more environmental coefficient of variation. A positive correlation with forage yield was abserved for triats of plant height, flag leaf length and internode length at 1% level and for water soluble carbohydrate and ashe at 5% level. Crude protein indicated negative correlation with forage yield at 5% level. Significant variation of morphological traits was observed among the studied accessions. The results of mean classification of the traits showed that the accessions including 10, 24, 23, 17 and 5 were better than the others for herbage yield. In view point of chemical traits the accessions 24 and 10 were preferable to others. Also the results of cluster analysis and discriminant function analysis classified the accessions numbers 10 and 24 in one group. Thus two accessions of 24 (Gorgan) and 10 (Semirom) were superior according to the results of the study done on the parameters under dryland conditions in Kermanshah province. Therefore, they could be regarded as the suitable genetic material for rangeland restoration or breeding programs.

In order to micropropagate Populus euphratica×P. alba and P. alba×P. euphratica, hybrids, shoot tips were harvested from research nursery of Biotechnology Department, Research Institute of Forests and Rangeland, Tehran, Iran. The buds were established after sterilizing by 0.1%W/V mercuric chloride for 1 minute on the MS medium containing 0.5mg/l BA and 0.01mg/l IBA. The shoots of the both hybrids were then transferred separately on 9 treatments, combinations of three different media (MS, WPM and DKW) with different ranges of hormones (IBA, 2iP and BA) in a completely randomized design with 3 replications and 3 time periods (every period was one month and each replication included 30 explants). The best treatment with the highest level of probability of shooting and the best growth in length were obtained using DKW medium with BA and 2iP by concentration of 0.5mg/l and 0.01mg/l IBA. Shoot rooting occurred in hormone free DKW medium after two weeks. The plantlets were established in polyethylene caps jam bottles, containing a light soil (1: 1: 1 peat, humus and sand) and kept in a germinator for acclimatization. They were acclimatized successfully and transferred to field after 40 days.

To evaluate the genetic variation of Tilia sp. in hyrcanian forest seed proteins of five populations including, Dalir, Chamestan, Band-bone, Valik-bone and Loveh were analyzed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Seed proteins profile with fruit morphology diversity were also investigated by discriminant analysis. Due to, three current types of fruits including rufous trichomes, prominent rib and without rib were selected. The different clustering pattern of individuals from same population, especially in Loveh in east of Hyrcanian forest, might be due to lack of germplasm exchange between the neighboring regions. Cluster analysis using data generated by SDS-PAGE bands seed protein patterns, clearly separated three fruit morphotypes. In general, this study proved relationship between the studied storage protein and fruits morphotype.

The research was carried out for considering the effect of water stress and accelerated ageing on several physiological characteristics ofpinus brutia seeds including germination percent, mean germination time, germination speed, germination energy and vigor index. Seeds were arranged in petri dishes with 4 replications in completely randomized design with five levels of water potential and five levels of accelerated ageing factor. Water potentials of the germination substrates (0, -2, -4, -6 and -8 bars) were produced using PEG-6000 solutions and seeds involving accelerated ageing treatment were exposed to 40oC and relative humidity of 100 percent for zero, 24, 48, 72 and 96 hours. Then seeds were kept for 37 days in germinator (16 h photoperiod at 1000 lux and at 20 ± 0.5oC). For measuring Electrical Conductivity (EC) test, seeds selected from all of accelerated age treatments exposed to 25°C in incubator for 24 hours. The results indicated that water stress and accelerated ageing had significant effect on seed physiological characteristics. Decreasing water absorption potential from 0 to -8 bars and increasing ageing period significantly reduced most of the seed physiological characteristics. The EC values were the least and highest in control samples and accelerated ageing treatments, respectively. Vigor index was more affecting water stress and accelerated ageing than germination percent.

Haloxylon aphyllum is an important plant species, which is widely used in sand dune fixation. Desirable characteristics of the species and high compatibility to arid areas caused the species to be increasingly planted in the areas. Since the species produces suitable high protein forage for livestock, during winter and autumn seasons, it could be used in livestock production as well as environment concerns. The research was carried out on progenies of 29 Haloxylon aphyllum genotypes, collected from four different sites, during 1998-2003 to select desirable genotypes, in Semnan province, using a randomized block design with three replications. Plant height, canopy cover, collar diameter, first lateral branch height from collar, seed production, pecil and trips resistance were recorded on the single plants. Cluster analysis and principal components analysis were used to evaluate qualitative variation between the studied genotypes in order to select the elite genotypes of the species to be used in breeding purposes, including seed orchard establishment. Eleven elite genotypes were detected based on the results of the experiment.