جستجوی مقالات مرتبط با کلیدواژه « کروموزوم » در نشریات گروه « زراعت »

The endosperm (3n) is the food source for the embryo, which has received two polar nuclei from the maternal parent 2n and one sperm cell from the paternal parent 1n. Traditionally, triploid plants are created by crossing between tetraploid plants and diploid plants. To carry out this method, it is necessary to create tetraploid lines, and it is possible to double the chromosomes of diploid species by using substances that inhibit the formation of the division spindle. The advantage of endosperm culture over the traditional method is that the production of triploid plants in endosperm culture is done in a single step, and the time required to generate a triploid plant is less than in the traditional method. Increasing the level of ploidy of the nucleus can affect the plant's physiological and biochemical processes as well as altering the rate of photosynthesis, respiration, activity of genes, enzymes, and expression of isoenzymes compared with diploid types. They will have a new phenotype and can surpass the range of traits of their diploid ancestors such as increasing biomass and changing the quality and concentration of plant active ingredients, increasing resistance to drought stress, and resistance to pests. Therefore, the chance of their selection will increase.

Immature seeds were collected in late May, about 35 to 45 days after pollination, and mature seeds were harvested after fully ripening approximately in late July, and disinfection using a stereomicroscope with 60 times magnification under a laminar hood. The endosperm tissue was separated from the seed coat and embryo. In this study, mature and immature endosperm tissues of the mooseer plant were cultured onto hormonal compounds for callus induction in dark conditions for three months. In further experiments, the effects of sucrose were investigated at two levels of 30 and 50 gl-1 and the combination of BAP and NAA treatments on mooseer production. The flow cytometry method and chromosome counting were used to determine the ploidy levels of regenerated plants.

In this study, the treatment of 1 mg L-1 of NAA and 1 mg L-1 of BAP indicated the highest percentage of callus formation in both mature and immature tissues of mooseer endosperm. Seedlings produced in the treatment of 0.5 mg L-1 of NAA and 3 mg L-1 of BAP in culture medium with 50 g of sucrose caused the production of bulblet with greater length and diameter. The present study identified the cytogenetic properties, chromosome counts, and stomatal sizes of triploid plants regenerated from both mature and immature endosperm tissue of mooseer, using flow cytometry. A total of 12 triploid seedlings were obtained from mature tissue, while 8 seedlings were obtained from immature tissue.

Traditionally, triploids are produced by hybridization between induced superior tetraploids and
diploids, but endosperm culture is a one-step protocol. In this study, according to the sexual and asexual propagation (propagation through daughter bulbs) of mooseer, the modification and production of the triploid plants in mooseer allow the propagation of this plant through daughter bulbs. Generally, triploid plants were successfully produced through the endosperm culture method.

Rapid screening of plant germplasm in the early stages of growth and determining the genetic basis of wheat leaf wilting index at the seedling stage is necessary for wheat breeding programs. In the present research, leaf wilting index for 290 Iranian bread wheat genotypes, including; 90 cultivars and 200 landraces were studied under drought stress conditions at the seedling stage in 2021 in research greenhouse of faculty agriculture of Urmia University, Urmia, Iran. The results showed that there was variation between the studied genotypes for leaf wilting index, and the landraces had significantly 12% more wilting scores than cultivars. This can be attributed to direct or indirect selection by breeders. The leaf wilting index of about 9% of cultivars and 3% of landraces were identified in drought stress tolerant group. GWAS had nearly the same results as general lineare model and MLM methods. Chromosomes 3B, 2A, 7B, 1A, 3A, 4B, 5B, 6A and 6B, respectively, had the highest number of marker-trait associations in the entire population which explained the phenotypic variation of the trait from 6 to 20%. Annotation of significant markers confirmed the results of GWAS analysis and showed that five markers on chromosomes 1A, 2A, 3A and 7B were aligned with different genes involved in drought stress tolerance. An integral component of membrane, protein phosphorylation, methyltransferase activity and zinc ion binding were part of the molecular functions and biological processes of the identified genes. The findings of this research provide a deep insight into the variation of leaf wilting traits in Iranian bread wheat germplasm under drought stress conditions, which can be used as selction criterium in the national bread wheat improvement programs.

Human activities such as mining and industrials activities have increasingly affected soil contamination through the sedimentation of heavy metals. This issue is concerned as a global problem. All heavy metals are potentially poisonous, which vary based on their biologic available concentrations and the sensitivity of organisms which are exposed to the heavy metal. One of the main heavy metals is Lead. lead is a potential pollutant that readily accumulates in soils and sediments. Pb is considered a major troublesome poison, crop productivity sharply declines in soils contaminated by Pb. The poisonous characteristics of lead on plants are attributed to chlorosis, declined growth, blackening of root system, upsets mineral nutrition and water balance, changes in hormone status, and the effects on the structure and permeability of membrane. In recent years, many plants have been destroyed due to the increased pollution of the earth by heavy metals, and which has led researchers are interested in soil improvement, the production and use of resistan. Most of the important agricultural traits, such as yield, grain quality and resistance, or tolerance of live and non-live stresses in nature, are complex qualitative traits. These traits are usually controlled by multiple quantitative traits (QTLs), which are strongly influenced by the genetic context of the creaturet plants, and the identification of mechanisms and genes associated with heavy metal tolerance. This research was carried to identification of QTL traits related to lead toxicity tolerance in barley.

In this study, we used 94 double haploid from Dom and Rec parents that were planted in a completely randomized design with three replications in twenty-cm diameter pots. Then at 2- to 3-leaves stage, seedlings were treated by 0 (control) and 2000 ppm density lead nitrate. Physiological traits such as sub-stomatal CO2, transpiration rate, photosynthesis rate, stomatal concentration and plant greenness after 24 under stress, were measured at the beginning heading stage. In order to investigate the frequency distribution of data and their variation under stress and normal conditions, Spss program version 23 was used. After observing the continuous and quantitative variation among progenies to studied traits, in order to locate the lead-tolerance genes, Using Mapchart2.32 and MapQTLs Software, chromosomal regions associated physiological traits were identified on seven chromosome of barley.

The phenotypic Analysis of the studied traits showed a quantitative and continuous variation. the studied traits showed normal distribution in both non stress and stress conditions The genetic which is lead tolerance is controlled depending on the physiological indices of different parts in the genome of the barely. In this study No QTL was observed for the studied traits under normal conditions. among the traits sub-stomatal CO2, transpiration rate, plant greenness after 24 under stress, stomatal concentration, photosynthesis rate, QTL was observed Under stress conditions with lead, two QTL discovered for sub-stomatal CO2 on chromosome 6, two QTL for transpiration rate on chromosome 3, four QTL for Stomatal Conduction on chromosomes 1 and 3, four QTL for photosynthesis rate on chromosomes 3 and 2, four QTL for plant greenness after 24 under stress on chromosomes 1 , 4 and 5. Phenotypic variation justified by these QTLs varied 10.5% to 19.10%.

The results of this study showed that the OWB mass mapping can be used as a proper mass mapping and as a model for studying the genetic of lead tolerance in plants. The results of this study also showed that various physiological traits of barely under lead stress conditions are manipulated by different genes. Precisely locating lead resistant QTL is the most important step in cloning and finding the function of the genes involved in lead resistance. In order to use QTL detection methods for understanding the attributes related to lead resistance, it is necessary to divide lead toxicity resistance into smaller traits. This task is achieved through considering the events occurring in lead poisoning and the determining the reason why some plants are tolerate.

Allium sativum is one of the most important, mostly used economical vegetable plants in Iran. Chromosome analysis or karyotyping is a test that evaluates the number and structure of chromosomes to study evolution. The present study was carried out to explore the cytological features, including chromosome number and karyotypic characteristics in a local cultivar of Allium sativum L., north of Iran (Gorgan, Sari, and Rasht accessions).

The root tip cells were treated first with 0.002 mol·L−1 8-hydroxyquinoline for 4 h at 4°C and then fixed for 24 h in fixative (1:3 glacial acetic acid/absolute alcohol) at 4°C. Finally, the root tips were softened with 1 M hydrochloric acid at room temperature for 8 min and stained for 10 min with acceto orcein 2% before being squashed between a glass slide and a coverslip. Root tip cells photographed at mitosis metaphase, which had well-separated chromosomes and a clear centromere. Long arm, short arm, the ratio of long arm to short arm, and chromosome index of mitotic chromosomes were calculated from metaphase plates. Figures summarized the idiogram for the three garlic accessions, based on the eight pairs of chromosomes’ short arm order length.

Basic chromosome number was confirmed as x = 8 (2n = 2x = 16). All the studied accessions cytotypes were diploid. The largest chromosome length belonged to Gorgan accesion as amount 169.51 micrometers, and the smallest chromosome length was obtained in Rasht accesion as amount 136.57 micrometers. The long arm of the chromosome was recorded between 4.85 to 6 micrometers. The short arm of the chromosome was measured between 3.18 to 3.80 micrometers. The Metaphase karyotype analysis revealed that centromeres were mainly located at the middle (metacentric - m) or near the middle (submetacentric - sm) of chromosomes. The chromosomes are arranged in decreasing order for short arm length, and the karyotype formula was obtained 12m+4sm for all accessions. Chromosomes 13 to 16 were submetacentric for both Gorgan and Rasht accessions. Submetacenteric Chromosomes were observed on chromosomes number 11-12 and 15-16 for Sari accesion. Three of the studied accessions were evolutionary located in one level according to asymmetrical karyotype, the value of TF% and separating to 2B classes based on Stebbins categories.

Regarding asymmetric karyotype and according to interchromosomal asymmetry (A2) as well as difference between the range of relative length (DRL), the most were found in Rasht accession (A2=0.34; DRL=6.99). A2 and DRL are two aspects of karyotype asymmetry related to shifts of the centromere position from the median to terminal or subterminal. The karyological data provide a comprehensive cytogenetic resource useful in cytotaxonomic research and assessment of their role in the evolution of Garlic. This resource can help better understand the taxonomy, evolution, and speciation in the genus Allium and identify candidate species for breeding programs.

Breeders are always looking for sources of diversity in different plants. Because spontaneous mutations occur rarely in environment, induced mutation is a more appropriate method for plant diversity. Therefore, the ploidy level instruction through mutagens, especially chemical mutagens in somatic cells, has the potential to improve the ability to produce new varieties with superior and desirable traits in many plant species. Plant species with more than two chromosome (polyploid) sequences are of particular importance due to increased genetic variation in their better adaptation to new environments, natural evolution and plant breeding. Accordingly, an investigation was conducted to induce in vitro polyploidy through colchicine in a new species of asiatic hybrid Lilium dandie, which has high potential for ornamental and medicinal.

In this experiment, in vitro bulb scales were treated in a completely randomized design with factorial arrangement in different concentrations of filter sterilized colchicine solution (0.01, 0.05 and 0.1%) for 6, 12 and 24 hours. Then samples were taken to regenerate and grow normally in a culture medium without growth regulators. After assessing the survival rate, ploidy levels of regenerated plantlets by direct counting of the number of root meristem chromosomes were determined. Length, width and density of leaf apertures using bachelor varnish technique and direct counting of chloroplast number of stomatal guard cells in adult and developed leaves as cytological factors between the control (diploid) and polypoid (triploid) plantlets was compared. plantlet fresh weight was also measured using scales and morphological indices of leaf length and width and root length were measured by precise ruler.

The results of this study showed that with increasing concentration and duration of treatment of colchicine, the survival rate of explants decreased. colchicine was completely effective in inducing polyploidy (triploid) L. dandie and the highest amount of polyploidy (14) occurred during 12 hours. The highest efficiency of productivity was obtained during treatment with 0.01% colchicine. In the polyploid plantlets, the stomatal density decreased significantly compared to the control, while the stomatal length and the number of chloroplasts in the stomatal guard cells showed a positive correlation with the increase in ploidy levels. Fresh weight and morphological characteristics of leaf length and width as well as root length in polyploidy plantlets were significantly increased compared to control.

The use of colchicine in polyploidy induction in L. dandie was completely successful and the highest polyploidy productivity (42.85%) was optimized for 12 hours treatment. Low density and longer stomatal length, as well as high chloroplast count in the chloroplast guard cells in polyploid plantlets, are a good indicator of polyploid plantlets screening than diploid plantlets. Fresh weight indices and morphological characteristics of leaf length and root width and plantlets length increased with increasing ploidy level.

Association mapping is a technique with high resolution for QTL mapping based on linkage disequilibrium and has shown more promising for describing genetically complex traits. In addition, it is a powerful tool for describing complex agronomic traits and identifying alleles that can contribute to enhance the desired traits. In this study, whole genome association mapping was used in a set of 148 spring barley cultivars. Phenotypic evaluation was conducted at Zahak Agricultural Research Station, Iran, using alpha-lattice design with two replications, for two croppinhg cycle (2014-2015 and 2015-2016). Traits such as days to anthesis, days to physiological maturity, grain filling period, flag leaf length, flag leaf width, grain number per main spike, thousand grain weight and grain yield were measured. Association analysis between the markers and phenotypic traits was performed with a mixed linear model (MLM with K+Q). In total 28 QTLs were identified which were related to the measured traits. A stable QTL was detected on chromosome 5H (74.76 cM) for days to anthesis. Three QTLs were detected on chromosomes 4H (125.08 cM and 120.64 cM) and 5H (74.76 cM) for grain filling period. One QTL on chromosome 2H (10.87 cM) was associated with days to anthesis, grain filling period and 1000 grain weight. One QTL on chromosome 4H (125.08 cM) was also associated with days to anthesis, grain filling period as well as flag leaf length and 1000 grain weight. Common genetic locations for these traits could be due to pleiotropic effects or genetic linkage.

This investigation was carried out to study the karyotype diversity of five garlic (Allium Sativum L.) varieties in Isfahan Research Center for Agriculture and Natural Resources. Karyotype of mitotic cells in metaphase of root apical meristem in germinated seeds was studied. The base number of chromosomes was x = 8 and all populations were diploid. Experiment was conducted as a completely randomized design with five replicates and mean comparison with Duncan's multiple range test (at 5%) among the five varieties of garlic. Based on Stebbins two-way table the Isfahan and Jiroft populations in class 3B and Bam, Kerman and Hamedan populations were located in class 2B. Analysis of variance showed significant differences for the total chromosome length, long and short arm length and the relative length of the shortest chromosome (p

In the present investigation، eight accessions belonging to three species of Stipagrostis were subjected to cytogenetic analyses. Results of chromosome count showed two ploidy levels of diploid (2n=2x=22) in S. plumosa and tetraploid (2n=4x=44) in S. pennata and S. karelinii. The chromosome number (tetraploid) of S. karelini is reported for the first time. Karyotypic formula obtained in the studied populations mostly included metacentric chromosomes. Satellite and nucleolus organizer region (NOR) were observed in diploid populations of S. plumosa. Karyotypic analysis and grouping of karyotypes with Stebbins method classified diploid population into 1A and 2A and tetraploid populations into 1B karyotypic classes. Considering this classification it could deduced that tetraploid populations containing asymmetrical karyotype. Analysis of variance of karyotypic traits showed significant differences for short arm length، arm ratio and centromeric index that indicating chromosomal variation among the studied genotypes. The highest correlations were observed between short arm with long arm، centromeric index with total form percentages and centromeric index with value of relative chromatin content (r = 0. 96، 0. 88 and 0. 87، respectively). The results of cluster analysis and Romero Zarco coefficient grouping were consistent and divided the populations into two separate groups. First group included three diploid populations from S. plumosa and the second group included tetraploid populations from S. pennata and S. karelinii species.

Karyologic studies were carried out on suitable metaphase cells of ten cultivars of Rapeseed (Brassica napus)، using squash technique، 0. 002 M 8-hydroxichinoline and 2% (w/v) aceto-carmin staining method. The chromosomal parameters measured were، short arm، long arm، chromosome volume، arm ratio، r-value، relative length and chromosome form percentage. Karyotype analysis showed that all cultivars were tetraploid (2n = 4x = 38). The resultant data were analyzed based on completely randomized design (CRD) with 5 replicates of cells. ANOVA indicated marked between-cultivars differences for most traits evaluated. On the basis of karyotypic formula، the cultivars had 4 types of chromosomes (M، m، sm، st)، categorizing in 8 different classes. Assessment of karyotype symmetry was carried out، using various parameters e. g. DRL، DI، TF%، S%، CV%، Stebbins and Romero-Zarco categories. The result of correlation coefficient showed that the short arm had the most correlation with form percentage، and chromosome volume had the least correlation with arm ratio. In cluster analysis based on UPGMA method، the distance was determined by eucldean distance dendrogram demonstrated 6 groups. The result of the principal components analysis showed that the first three components coverd 96. 1% of the data variation. According to the first two PCs، the cultivars were categorized into 6 groups.

In order to deliberate karyologic and cytogenetic parameters, fifteen Aegilops populations, collected from different regions of the country, were studied. These populations included 3 diploids of Ae. tauschii, 6 tetraploids of either Ae. triuncialis or Ae. cylindrica species. The resultant data were analyzed according to a 2-factorial experiment on the basis of a completely randomized design (CRD) with 5 replicates of cells. The factors considered were populations (3 and 12 levels) and chromosome (7 and 14 levels) for diploids and tetraploids, correspondingly. The ANOVA results indicated conspicuous between-diploid differences for L, S, TL and r-value, between-tetraploid differences for RL%, and between-chromosomes either diploid or tetraploid differences for L, S, TL, RL% and F%. Mean comparisons were carried out, using LSR test. Both type populations differed in satellite number, ranging from 0 to 2 pairs. The most chromatin length was detected in pop. 11 (152.18 µm), while pop. 2 bore the least (70.52 µm). Among 15-population karyotypes, 10 were determined in 1A class of Stebbin's classification vs. 5 in 1B class. According to Levan's chromosome nomenclature, the chromosomes of 5 pops. were identified as medium region " m " and those of 10 pops. as both medium region " m " and sub medium region " sm ". Chromosome banding has proven to be a valuable tool for karyotype analysis and for rapid detection of gross chromosomal rearrangements, including large deletion and insertion mutation as well as transpositions. This research was carried out towards an establishment of a procedure, OR-banding, for the detection of the Aegilops chromosomes. Chromosomes OR-banding technique was investigated on 3 Iranian pops. of Ag. tauschii. Chromosome slides were prepared via squash technique in different intervals (24 h to one week) after being slained with 1% aceto-orcein dye. Chromosomal banding pattern was observed 3 d after staining. It was shown that the number of the bands decreased from prophase to metaphase stages of mitosis. The best time for observation of the OR-Banding pattern in Aegilops samples was a long-term (one week) past remaining of the root meristems in dye. This method can be empolyed for an identification of metaphase chromosomes in wild relatives of wheat.

Fenugreek (Trigonella foenum-graecum) is an annual herbaceous plant belongs toPapilionaceae family and is important as a pharmaceutical, agronomic and pasturalplant. In order to study the effect of trifluralin on ploidy induction and cytogeneticcharacteristics of cells in the root meristem of fenugreek some seeds of this species wereplanted in the incubator and after germination root tips were used for karyotypic studies.For treating the seeds trifluralin liquid 48% were applied at 7.5, 15 and 22.5 μMconcentrations for 12 and 24 h. The Video Analysis System was used for karyotypeanalysis. The basic chromosome number was X=8. The results showed thatconcentration of trifluralin, treatment duration and interaction between them on theploidy induction were statistically significant. The maximum ploidy induction washappened by immersion seedlings in 22.5 μM trifluralin at 24 h. The result of analysisof variance based on completely randomized design (CRD) showed a significantdifference among the karyotypes for all chromosomal traits (P<%1). Trifluralin affectedseverity on the length of chromosomes and karyotypic formula so that the longestchromosomes belonged to the karyotype control sample and the shortest chromosomeswere observed after treating with trifluralin. After applying treatment was reduced thepercentage of submetacentric chromosomes and were added to the percentage ofmetacentric chromosomes.

 Annual species of Medicago are important pasture legumes in western parts of Iran. Due to limited karyotypic reports on annual Medicago species, the present study was conducted on accessions available in gene bank of Iran. Total length of chromosomes, size of long and short arms and their ratio were the basis for karyological measurement. Karyotypic studies showed that M. radiata 29 , M. radiata 588, M. minima 316, M. polymorpha 1123, M. orbicularis 449, M . li tiralis 1038, M. trancatulla 1146 and M. polymorpha 612, carried 2n=2x=16 chromosomes and Medicago rigidula 2n=2x=14 chromosomes. Among species with 2n=2x=14, M. rigidula 1126 had the highest total chromosomal length and M. rigidula 454 the least total length. Species M. littoralis 1038 and M. minima 316 both with 2n=2x=16, had the highest and the lowest total chromosomal length, respectively. Total chromosome length and mean of chromosome length in most of exotic species were more than those of landraces. Species and varieties with larger karyotype had larger seed size. B chromosome found only in the M. littoralis and M. polymorpha species. Satellite chromosome observed in varieties 606, 1126 and 1199 of M. rigidula, 1123 and 612 of M. polymorpha and M. radiata 588. Resultes of cluster analysis revealed that varieties and species with similar karyotypice size and mean chromosomal length, did not show any significant differences, hence they were located in one group. Factor analysis revealed that chromosomes number 5, 6, 7 (2x=14) and 7, 5, 2 (2x=16) showed maximum structural change among accessions. Karyotype symmetry were determined by using coefficient of variation (CV) and total form percentage (%TF). Resultes of CV showed that the most of variation between chromosomes belongs to M. polymorpha 612 and the least of variation between chromosom es belongs to M. rigidula 1128. According to TF, M. minima 316 had the most karyotype symmetry and M. rigidula 1126 showed the least karyotype symmetry.