پژوهشنامه اصلاح گیاهان زراعی
پیاپی 10 (پاییز و زمستان 1391)

This study was conducted to assess the sources of genetic and phenotypic variability of Common bean genotypes. Fourteen morphological and agronomic traits were measured on 49 common bean genotypes. These traits included: days to 50% flowering, days to 50% Podding, pod length, pod wide, seeds per pod, seed length, seed wide, stem diameter, seed and pod weight, number of full pod, number of total pod, seeds per plant, 100-seeds weight and seed yield per plant. The multivariate data set was analyzed using Canonical Discriminant Analysis (CDA) in combination with a clustering procedure. In this analysis, the first two canonical varieties were significant and justified 88.5% and 94.7% of variances in normal condition and drought stress, respectively. According to cluster analysis, genotypes were divided in 4 categories. Canonical discriminant analysis is useful in identifying the genetic variation and describes the variation among common bean genotypes. Cluster Analysis was successful in differentiating the varieties into similar subgroups based on the measured traits.

The active oxygen species are the most important plant stress agents. Superoxide dismutase is a key enzyme which constitutes the first line of defence against oxygen toxicity. This enzyme is necessary for aerobic life and play an effective role in the process of tolerance to stress and plant longevity. Aeluropus lagopoides is a halophyte plant that tolerate high soil salinity and have high activity of superoxide dismutase enzyme. We used the sequences of SOD genes from another plants in Poaceae family for primer designing and isolated genes from halophyte plant Aeluropus lagopoides. In this investigation two novel SOD genes AlSOD1 and AlSOD2 isolated and cloned in E.coli via pTZ57R/T cloning vector. These two genes encoding 152 amino acids and also have high homology with Cu/Zn SOD Aelurous littoralis, Zea mays, Phyllostachys edulis and Oryza sativa with 92, 89, 88 and 87% respectively.

In order to study of variation and the effect of 5 salinity level (0, 75, 150, 225 and 300 mmol) of NaCl on 20 alfalfa genotypes, a factorial experiment was conducted based on CRD with three replications in green house condition of Shoushtar Islamic Azad University, Iran in 2011. Seeds were sown in pots containing 1:2 sand-agriculture soils and irrigated by tap water for 45 day. Then the pots were irrigated by salt water for 14 days. Seedling characteristics as number of leaf per plant, root length, stem length, seedling length, seedling root shoot length ratios, seedling fresh and dry weight and dry fresh weight ratios were measured. The results of analysis of variance showed significant effects of genotypes, stress and genotype by stress interaction effects for all of traits (P<0.01). By increasing salinity all traits were decreased except root shoot length ratios. The results indicated that the critical salt dose for shoot and root caracterstics were 150 and 300 mmol, respectively. Using cluster analyzes, the genotypes were split into three groups. KFA1, KFA11, KFA14 and KFA15 originated fro GarehYounjeh, KFA4, KFA6 and KFA16, originated from Hamedani and cultivar Bami Garmsiri were considered as the most tolerant groups and KFA3, originated GarehYonjeh, KFA5 and KFA17, originated Hamedani, KFA7 originated Rahnani, cultivars Nikshahri Garmsiri and Yazdi Garmsiri were considered as the most sensitive groups and the other ones as semi-tolerant to salinity stress.

In order to investigate the role of wheat ploidy levels and comparison them with Triticale and Tritipyrum amphyploids for grain yield and it's components, genotypes of diploid, tetraploid, hexaploid wheat, Triticale and Tritipyrum were evaluated under field condition in a completely randomized block design with three replications in autumn and spring planting seasons. The results indicated that sufficient genetic variation exist within and between species for all the traits. Effect of planting season and genotype × season interaction were significant and the traits have decreased in spring in comparison with autumn cultivation. Orthogonal comparison of species revealed that diploid wheat showed higher number spikes per m-2 and biological yield, but it produced lower level of number grain per spike, 1000 grains weight and grain yield and harvest index. Triticale produced the highest grain yield, with showing high number grain per spike and 1000 grains weight. Overall these differences could be resu-lt of genome role and planting season in preferment of the traits. The correlation coefficients between grain yield and traits indicated that, grain number per spike has higher correlation with grain yield in comparison with other traits in tetra and hexaploid wheat. One thousand grain weight showed more important role in grain yield in hexaploid wheat compare to tetrapolid wheat.

In order to use of haploid tissue of sugar beet for producing transgenic plants, at first, some experiments were accomplished for shoot production of haploid leaves from haploid embryos. Results of current study indicated that MSB or PGoB medium supplemented with 3% sucrose, 0.2 mgl-1 BA and 0.5 mgl-1 NAA could be used for increasing haploid embryos and half strength MSB medium contains 1% sucrose to develop embryos and shoot production. Moreover, PGoB medium supplemented with 1 mgl-1 BA and 1 mgl-1 NAA was used for shoot production from haploid leaves. In the next step, haploid embryogenic calli and leaves were inoculated with Agrobacterium tumefaciens cells harboring pBI121 binary vector. After 2 days co-culture, the inoculated explants were transferred to selection medium contains 50 mgl-1 kanamycin. After 3-5 weeks, putative transgenic shoots were analyzed by GUS staining. Results showed that two explants have ability for shoot regeneration of haploid transgenic cells.

Callus induction and plant regeneration potential of rice cultivars (Tarom-jelodar, Sangtarom, Tarom-danesh and Neda) were studied. MS medium culture containing 3 levels of 2, 4-D (2.0, 2.5 and 3.0 mg/l), for callus induction and MS medium culture containing different levels of BAP, NAA and Kin hormones for plant regeneration were used. These experiments were conducted at completely randomized design with Factorial arrangement with 4 replication in the biotechnology laboratory of Sari Agricultural Sciences and Natural Resources University (SANRU) in 2010. The results showed that Tarom-danesh cultivar had the highest (81.92%) and the Tarom-jelodar cultivar had the lowest (23.82%) percentage of callus induction. Generally, cultivars’ reactions to callus induction in 2.0 and 2.5 mg/l concentrations of 2, 4-D were more than 3.0 mg/l concentration of this hormone. The interaction between 2, 4-D concentrations and cultivars showed that Taromdanesh cultivar in all of 2, 4-D concentrations and Neda cultivar in levels of 2.0 and 2.5 mg/l 2, 4-D had the highest amount of callus induction. The plant regeneration showed that Tarom-danesh (= 20.0%) and Neda (= 16.7%) cultivars in treatment of BAP and Kin had the highest regeneration percentage, respectively. Also Tarom-jelodar cultivar in treatments of BAP and Kin had the least (3.3%) percent of green plant regeneration.

Achievement to low-priced and short-term methods for obtaining of tolerant lines to abiotic stresses in plant breeding programs is one of the main applications of tissue culture. In present study, the callus formation potential of immature embryo, hypocotyl and root explants of Sahel, Sepid, No. 200, Barbadense and Khordad cotton cultivars were investigated on MS basal medium containing various hormonal combinations of 2, 4-Dichlorophenoxy acetic acid (2, 4-D) and 6-Benzylamino purine (BAP). According to analysis of variance, callus formation percent was significant at 1% level for cultivar, explant type, hormonal combinations of medium and explant × hormonal combinations of medium interaction. On the basis of the mean comparisons by Least Significant Difference (LSD) Test, the highest callus formation was related to immature embryo explant of No. 200 cultivar on the MS medium containing 0.5 mg/l 2, 4-D, whereas, the root explant of Sepid cultivar showed the lowest callus formation percent. By transferring the produced calli on MS medium containing different concentrations of sodium chloride (NaCl) and then studying the relative growth rate of calli, it was revealed that the tolerance of explants to different concentrations of NaCl was significant at 1% level affected to cultivar, explant type, NaCl density and all their interactions. The highest relative growth rate of calli on the salinity medium was related to immature embryo explant and Khordad and Sepid cultivars with 77.3% and 76.2%, respectively, while the root explant of No. 200 cultivar with 17.9% showed the lowest tolerance to NaCl. The relative growth rate of calli showed significant reduction in all explants and cultivars with increasing of NaCl densities, as, the control treatment (without NaCl) has been the highest relative growth rate with 51.6%, and the lowest relative growth rate with 20.6% was observed on MS medium containing 3 mg/l NaCl. By transferring of the selected tolerant explants to the media with higher concentrations of 3.5 and 4 mg/l NaCl, it was determined that none of the calli and explants could not tolerate the higher NaCl densities in the medium.

In present study, factor analysis and contribution of traits ingeneration of quantitative traits in barley were studied. Fourteen genotypes of barley were examined using a Split- Plot design based on Randomized Complete Block Design (RCBD) with three replications. Levels of water stress treatments were defined as main plot (perfect, ½ and no irrigation) and genotypes were considered as subplot. A positive significant correlation (P<0.99) was indicated between grain yield and dry matter remobilization of stem. Factor analysis determined five factors for perfect and of ½ irrigation and four factors for stopped irrigation that explained 83.9, 83.7 and 74.1% of the data’s changes. In general, contributions of dry matter remobilization from stem and peduncle to grain were highly important in all three stress levels. By increasing the stress level, dry matter remobilization from stem and peduncle to grain, seed weight, plant height, second intern ode length, peduncle length and spike length were more effective than traits like efficiency of remobilization from stem and peduncle to grain, number of seed per spike and grain yield in screening of genotypes. Overall, it can be concluded that traits related to remobilization can be considered as important indicators for evaluating and screening of barley genotypes under drought stress conditions.

Understanding the physiological basis of crop yield is crucial factor to identify key traits limiting yield under water stress conditions in order to crop breeding. Modeling is a new approach to understand the physiological basis of crop growth and development. This study was carried out in order to identify traits determining wheat yield under drought stress conditions using odeling approach. To achieve this goal the model verification test was done firstly on SWB-WGro model, which was previously validated at Mashhad region. Then key traits to design wheat ideotype were identified using sensitivity analysis technique. Results of verification test showed that the ability of model for simulation of final yield was excellent under different water supplies range (RMSE% = 4.32-9.71). Finally, the suitable ideotype for water stress conditions in Mashhad region was defined as a plant with thinner and vertical leaves, which have a high nitrogen concentration, longer stay-green, lower pre-anthesis development rate and higher post-anthesis development rate.