Seed and Plant
Year:2008 | Volume:24 | Issue:3|Papers Count:18

Stripe rust is one of the most important fungal diseases of wheat that has been reported in all continents and more than 60 countries in the world. Wild emmer wheat, Triticum dicoccoides, the tetraploid progenitor of cultivated wheat, has proven to be a valuable source of novel stripe rust resistance genes for wheat breeding. G25accession of this species has Yr15 gene that confers resistance to 31 stripe rust races and pathotypes. It has been mapped on chromosome IBS. In the present study, as a first step towards mapbased cloning of Yr15, it was fine-mapped in a F2 population with 825 individuals. According to frequency of retrotransposons in euchromatin regions of the genome and I near the gene cluster, retrotransposon-based molecular markers were mostly used. Three SSR, three IRAP and seven REMAP markers were identified to be linked to the gene with a distance less than 2cM and genetic map near the gene was saturated. Some markers were cosegragated at proximal side of the gene. One of the lRAP and two REMAP markers converted to locus specific and codomiriant SCAR markers. Locus specific and codominat marker, SC792, completely co-segragated with gene. Other two locus specific and codominant markers, SC1600 and SC1028, surrounded the gene in an interval of 1cM. These markers could be used for reliable MAS and map-based cloning of Yr15. Also, it was demonstrated that retrotransposon based markers can be more useful and efficient in fine-mapping of genes controlling agronomically important traits.

Parsi zira (Buniumpersicum Boiss.) that is also called mountainous or black zira, is one of the most important medicinal plants with high economic importance. There is a little infonnation about in vitro culture of Parsi zira. Fragmented embryo was used as an explants in Bunium persicum regeneration. In this method, a great callus induction and regeneration occurred only on the same medium without any subculture. In this research, MS media containing different concentrations of plant growth regulators, NAA and 2,4-D alone or together with Kin, were used. The experiment was conducted using completely randomized design with 30 treatments and 10 replications per treatment. The treatment containing 0.1mg-1 NAA and 2mgl-1 Kin was the best one for regeneration. The treatment containing 0.1mg-1 NAA and 0.5mg-1 Kin was the best one for somatic embryogenesis. Regeneration occurred in some treatments without kinetin, showing that kinetin is not essential for Buniumpersicum regeneration.

In order to study the general combining ability (GCA), specific combining ability (SCA) and heredity ability in rapeseed, eight genotypes were crossed using line tester method. Fifteen hybrids together with eight parents were compared in RCBD with three replication during 2002-2003 at Agricultural Research Station of Bayekola, Mazandaran. Mean of squares of GCA and SCA were significant for many of traits indicating significant differences for GCA effects of parents and SCA effects of hybrids. Estimation of degree of dominance more than one, and low heritability for plant height, total number of pods per plant and seed yield, indicated over-dominance gene effect and prime importance of nonadditive gene effect for controlling above mentioned traits. Thus, producing hybrid seed for utlization of non-additive gene effects of these traits will be fruitful. For number of days to maturity, 1000-seedweight and oil percentage, additive gene effects were more important. Thus, breeding based on selection for these traits will be effective. Among parents, Quantum and Legae and among testers, Foseto had high significant GCA effect for seed yield and some other traits. Therefore, these genotypes can be used for seed yield improvement. Among crosses, Foseto x Legae had the highest seed yield and high amount of SCA effect for number of seed per pod, number of pods plant and 1000 seed weight. In general the crosses with high SCA effect for seed yield, had at least one parent with high GCA effect, thus selection based on GCA effect of seed yield can be effective for improving SCA effect of seed yield

In order to study the genetic diversity of yield and its components, and also some of morphological and phenological characteristics, 364 soybean genotypes were studied, based on an augmented design with three checks and six blocks, in Seed and Plant Improvement mstitute, Karaj, Iran, during 2003-04. These genotypes (35 determinate, 183 semi determinate and 149 indeterminate, most of them were from 1-4 maturity groups) were included mostly imported genotypes and some of germ plasm from national breeding programs. Results showed that there were highly significant differences among genotypes for all studied characteristics, because they were from different maturity groups. Number of pods in branches, number of branches and number of sterile nods in the beginning of maturity stage, had high phenotypic coefficients of variations. The percent of oil and protein and number of nods in the beginning of seed constitution stage had low phenotypic coefficients of variations. The results of simple correlation showed that the biomass, number of seeds and number of pods per plant had high correlation with seed yield per plant. The traits related to growing stages such as days to complete flowering and days to complete maturity, had significantly positive correlation with plant height (P<1%). Based on cluster analysis, 364 genotypes were classified in three groups for yield and its components traits. The discriminate functions for three groups, obtained by cluster analysis, were also formulated. Two functions described 100% of variance among genotypes. The most important characters for distinguishing these groups were number of seeds per plant, seeds yield and biological yield.

Lentil (Lens culinaris Medik.) is an important widely caltivated food legume crop in Bilehsavar, Moghan, northwest of Iran. Wilt disease caused by Fusarium oxysporum f. sp. lentis (Vasd. and Srin.) Gordon, has been appeared severely in this region during recent years and caused sharp failing in yield and cultivation areas of lentil. To find resistant cultivars suitable for the region, responses of 32 lentil promising lines were evaluated for four years in glasshouse and field conditions. In the glasshouse, plants were artificially inoculated by immersing root tips in spore suspension, and also by sowing seeds in infected soil in pots. Field experiments were carried out in a highly naturally infected farm. In all experiments responses of plants were recorded based on the percentage of dead plants. Cluster analysis of the glasshouse and first year field data led to selection of lines that were resistant in these experiments and also in two following years experiments in field conditions. In the fourth year, the selected resistant lines were evaluated for some important agronomic traits in the same farm. Based on the results of four years, lines ILL6037 and ILL7531 were selected as the most resistant and suitable lines for the region.

Incompatibility is one of the important genetic factors that affect pear fruit set. This experiment was carried out to survey incompatibility alleles in some Asian pear genotypes. PCR with specific primer designed for incompatibility alleles were used. Genomic DNA of nine Asian pear cultivars (KS6, KS7, KS8, KS9, KS10, KS11, KS12, KS13 and KS14) and two hybrids from their crosses was extracted and incompatibility alleles were amplified by specific primers designed for S alleles. Incompatibility alleles in Asian pear cultivars KS6, KS7, KS8, KS9, KS10, KS11 and KS12 were a couple of SI or S3-S7 alleles. One the incompatibility alleles of KS13, KS14, hybrid 1 and hybrid 2 was S2 and the other allele probably was S1 or S3-S7. PCR technique is an easy way for S allele identification and is not affected by pollination factors.

One hundred and eight isolates of Fusarium verticillioides, the causal agent of fusarium ear rot of corn collected from different geographic regions of Iran during growing season in 2005, and two standard tester isolates of F. verticillioides obtained from South Africa were chosen to be analyzed by AFLP markers to determine their genetic diversity. Total DNA of each isolate was extracted and digested by EcoRI and MseI endonuclease restriction enzymes and then digested fragments were ligated to site-specific double strands adapters. The products of a PCR reaction with non-selective primers were diluted and used in a selective PCR reaction applying five primer-pair combinations of MseI and p33 radioisotope labeled EcoRI. The final products of selective PCR were loaded and separated on a 5% polyacrylamide gel. The 98 polymorphic bands were scored manually and the dendrogram generated by UPGMA method based on Dice similarity coefficient as well as principal coordinate analysis (PCoA), grouped all of the F.verticillioides isolates into eight major clusters (A-H). The fingerprintgooup A with 98 members was the largest group and the other groups contained between one to three members. Based on the results of analysis of molecular variance (AMOVA) high genetic diversity was observed within each population and low genetic diversity was observed among all populations which it may be due to some variation factors such as mutation and gene or genotype flow.

Half diallel crosses of nine Iranian wheat cultivars were used for graphical analysis and estimation of genetic parameters related to yield and its components. Parents with F2 generations were evaluated in a randomized complete blocks design with three replications. The analysis of variance revealed significant differences among genotypes for all traits except tiller number and grain weight per main spike. The test of Jinks and Hayman revealed that assumptions are valid for flag leaf length, plant height, grain yield per plant, main spike length and peduncle length, but for flag leaf width and peduncle weight when one parent was excluded, the assumptions were fulfiled. According to the estimations of average degree of dominance and results of graphical analysis, the gene actions for flag leaf length, flag leaf width, plant height, grain yield per plant, main spike length, peduncle length and peduncle weight were partial dominance.

Wheat breeding for heat and drought tolerance provides possibility in better using of arid and semi-arid regions and increase land area and stability of wheat production. Forty wheat genotypes in a heat tolerance nursery from CIMMYT were evaluated in alphalattice design with two replications in Gachsaran Agricultural Research Station in 2004- 2005 cropping season. Selected lines were tested in another experiment using randomized complete block design with three replications in 2005-06. The results showed that synthetic derivatives had higher early growth vigor, earliness from one to five days in comparison with check, optimum plant height, moderate spike length and tiller, relatively higher thousand kernel weight in dryland conditions (33 g) and grain yield up to 35 percent more than the adapted bread wheat check cultivar (Zagros). Successful performance of these lines under various intensity of heat and drought stresses, indicate the promising application of these genotypes in large ared and various semi- tropical drylands. However, some common wheat lines had close competition in view of agronomic traits and grain yield with the check cultivar.

To study inheritance of morphological traits associated with earliness and their relationship with yield, six genotypes of cotton were studied in a half diallel cross in 2003 in Darab. Fifteen Fl and six parents were evaluated in a complete block design with three replications. The results showed that differences among treatments were significant for seed cotton yield, earliness, plant height, date of first squire and mean maturity data. General and specific combining ability (GCA and SCA) effects were estimated by the method 2 of the Griffing's model I.Mean square of general combining ability (GCA) was significant for all studied traits. Specific combining ability (SCA) was significant only for yield. GCA/SCA ratio was significant for all studied traits except for yield. Determination of genetic parameters, statistical indices and graphical analysis by Jinks-Hayman method showed that gene actions for yield and earliness were over-dominance, while plant height, days to first squire and mean maturity data showed partial dominance. All of the traits had high board sense heritability: Narrow sense heritability was also high for all traits except yield.

Fire blight caused by Erwinia amylovora (Burr.) Winslow et at., has the highest importance among different diseases of pome fruits in many countries. Use of resistant or tolerant cultivars has been suggested as the most economic and effective method to control the disease. In this research different isolates of fire blight causal agent bacterium were isolated and evaluated biochemically and pathologically to select the highly virulent isolates for subsequent use in screening of quince (Cydonia oblonga Mill.) genotypes to the disease. Five isolates out of 25 primary isolates successfully passed all biochemical and phytopathological identification tests. Two iS9lates obtained from Zanjan province (Z1 and Z2) and one isolate from Tehran province (K2) expressed more virulence that shows their appropriateness in the screening of genotypes. Modeling of carbon source utilization by isolates confirmed homology of the isolates and revealed potential of bacterium to metabolize sucrose, glucose fructose faster than other carbohydrates. Regarding to the dominance of sucrose and glucose in Rosaceae family, it seems that limited host range of bacterium at least in part, is depending on the accessibility of an appropriate carbon source in the members of this family. Test of resistance to the antibiotics revealed existence of an eventual high streptomycin resistance in K1 isolate that is the first report in country.

Fire blight (Erwinia amylovora) is an important and catastrophic disease of pome fruits in Iran. Among various host plants, the quinces (Cydonia oblonga Mill.) trees usually suffer more damages than other hosts. Resistance of indo- and exogenous germplasm of pear and apple of Iran to the disease has been evaluated previously both in the greenhouse and orchard conditions. This study was carried out to evaluate fire blight resistance in some Iranian quince genotypes, respecting to the high susceptibility and genetic variation of quince in Iran. After isolation and appropriate tests of bacteria, thirteen quince genotypes of central region of Iran, as well as cultivar Isfahan (encoded as KVD3) as control, were propagated on quince seedlings and screened for fire blight resistance during a three years period (2004-2007) in the greenhouse condition, using K2, Z1 and Z2 isolates of bacteria. Resistance was evaluated by survey of necrosis progress rate at 4, 8, 17 and 22 days after inoculation, and index of varietal susceptibility (I.V.S.) in the shoots. The cultivar Isfahan with 50% and genotype SHAI with 90% final disease progress showed the lowest and the highest susceptibility to the disease, respectively. Correlation analysis between different characteristics demonstrated the highest relation of fire blight resistance with vigor of lateral bud growth, especially at the beginning of disease establishment (first 4-8 days) in the shoots.

In order to study the reaction of fifteen maize hybrids to different levels of drought stress, and evaluate drought tolerance indices, an experiment was conducted in split plot arrangement using randomized complete block design with four replications in Gharakhil (Ghaemshahr) Agricultural Station, in 2006. The main plots consisted of drought stress levels and sub-plots included maize hybrids. Six drought tolerance indices were calculated for grain yield. Under normal, mild and severe stress conditions, hybrid OSGT14 produced 9.445, 9.270 and 8.352 tha-1, respectively, while under most severe stress, hybred SPGT12 produced the highest grain yield (7.455 tha-1). Based on the highest correlation observed between grain yield and different (indices, MP, GMP, Harm and STI, were suitable indices. Biplot analysis determined hybrids OSGT14, KSC710GT and KSC-mog 84-062, in group A, as tolerant hybrids and suitable for normal and stress conditions, and hybrids BGT10, KSC 708 GT, BGT15 and KSC712GT as susceptible hybrids. Cluster analysis based on different indices, divided hybrids under mild and severe stress conditions, into five, and under most severe stress into six groups. Indices MP, GMP, Harm and STI, identified hybrids OSGT14 and KSC710GT as tolerant, and BGT15 and KSC708GT as susceptible hybrids to drought stress, while, indices TOL and SSI showed KSC 720 and KSC700 as tolerant and KSC712GT and BGTI0 as susceptible hybrids to drought stress.

Study on genetic variation is an important feature in plant breeding. Knowledge on genetic variation of plant populations enables the breeders to select better methods for breeding of their materials. The present study was carried out in a lattice design in Sararood Dryland Research Station during 2001 to investigate variations of different traits in 56 genotypes of safflower. Analysis of variance on different traits showed significant differences among genotypes for number of sub branches at 5% probability level, and at 1% level for other traits indicating genetic variations for different traits ill genotypes. Path analysis revealed that the most diryct effects were those of the number of heads per plant (0.557). Factor analysis extracted four factors. Factor loading of first three eigen values showed that first three factors explained 97.239%, sum of variance. Rates of first, second and third factors were 35.195%, 31.114/% and 30.193%, respectively. The first, second and third factors were named productivity factor (seed yield and oil yield), sink factor (number of sub branch and number of heads per plant) and fixed capital factor (number of days to 50% flowering, number of days to maturity and plant height), respectively. Cluster analysis divided genotypes into four groups. Group three with 17 genotypes that they had higher number of sub branches, number of head per plant, seed yield and oil yield than general mean. In general, selection indices under rain fed conditions were introduced as seed yield, number of head per plant, number of sub branches, and number of days to 50% flowering, number of days to maturity and plant height.

Seventeen genotypes of bread wheat along with three check cultivars were evaluated for some important traits related to drought tolerance, including germination stress index (GSI), rootlet number and length, coleoptile length, proline content of flag leaf, cell membrane stability, relative water content (RWC), excised leaf water content, chlorophyll a and b content, stress tolerance indices (STI and TOL) and other morphological traits under field and laboratory conditions. The experiments were conducted in RCBD with three replications in Dryland Agricultural Research Institute, Sararood Station, Kermanshah, in 2003-04 and 2004-05 cropping seasons. At the seedling stage, the genotypes Bow "S"/Gen//Shahi, Ghods *3/Kavvko // Ghods *3/Ka zl Kavko, Gene Bank- 914, 4848 MashhadiTui "S" IRW92 1D6 and Roshan/3/F12. 71/Coc//Gno79. performed better than the others. However, in field conditions based on relative water content, praline content, cell membrane stability, chlorophyll content under stress condition, and stress tolerance index, four genotypes were selected. Simple correlation coefficients revealed (that STI had high and positive significant relation with grain yield, different traits in germination stage, and germination stress index, while showed negative and significant relation with cell membrane damage. Based on the overall results, four superior genotypes were selected for further stage of selection. The genotype Ghods*3/Kavvko//Ghods*3/Kaz/Kavko had most of the traits effective on drought tolerance as well as higher yield in both years.

To compare three wheat genotypes for producing the haploid and doubled haploid through chromosome elimination, an experiment was carried out using F1 population from the crosses Raptor´Pishtaz, Norstar´Pishtaz and Mironovskaya´Pishtaz. Measured traits were seed set percentage, embryo and haploid seedling development and were analyzed statistically using X2 test. Among three genotypes, there was significant difference concerning the percent of seed and embryo forming, but significant difference was not observed for haploid plant. Raptor´Pishtaz showed the highest value for seed set, Mironovskaya´Pishtaz the highest value for haploid plants and embryo forming percent, and Norstar´Pishtaz the lowest level of haploid plants and embryo forming percent. According to the results, the seed set and embryo number traits, when the same number of florets are pollinated, can be considered as an important trait in genotype selection for production of doubled haploid plant. This experiment also showed the dependence of chromosome elimination trait to genotype.