Journal of Plant Molecular Breeding
Volume:6 Issue: 2, Summer and Autumn 2018

Assessment of genetic diversity and individual relationships in rice (Oryza sativa) germplasm collections seems to be necessary for future rice breeding program. In order to understand genetic relationships of 30 rice genotypes, nine morphological traits, seven physicochemical properties and twelve RAPD primers were used for study of 30 rice genotypes. Among morphological traits, number of unfilled grain, number of tiller, number of filled grain and plant height had the highest CV value that indicated the high range of genetic diversity for studied genotypes. Pairwise correlation of morphological traits and physicochemical properties showed plant height had a strong positive correlation with panicle length (r = 0.721, P< 0.0001). Also, ratio of white rice to paddy rice and milling ratio had a negative correlation with plant height and 1000-grain weight, respectively. Cluster analysis of physicochemical properties and morphological traits grouped all genotypes into three main clusters. A total of 105 obtained RAPD bands, a number of 35 bands were polymorphs which range 7 to 19 bands per primer. OPB-14 and OPH-12 primers shown that lowest and the highest number of bands per primers, respectively. Cluster analysis of molecular data based on UPGMA algorithm and Jaccard's similarity coefficient grouped 30 rice genotypes into three clusters. The findings of this study might provide valuable information about local rice cultivar relationships in terms of their genetic distance, and can be useful in rice breeding program.

Precise investigation of genetic diversity by means of novel molecular tools has made it possible to identify the superior genotypes among various male and female pistachio populations. Cytogenetic studies have shed light on the possible presence of distinct sex chromosomes in male and female genotypes. In this study, 22 start codon targeted (SCoT) primers were used to investigate the genetic diversity of 22 male genotypes and 22 female cultivars of pistachio. A total of 434 loci were produced that 339 loci were polymorphism. The average value of polymorphic information content (PIC), marker index (MI), and resolving power (Rp), ranged from minimum 10, 0.5, and 1, to maximum 31, 11.40, and 17.86% subsequently. The genetic similarity between genotypes, were calculated using Jaccard's coefficient, ranged from 35 to 66%. The cluster analysis divided pistachio genotypes into six groups, and could efficiently differentiate the male and female genotypes. Analysis of molecular variance (AMOVA) classified the total diversity into intra- and inter- population diversities with a high genetic variation (92%) within populations. This study reveals that SCoT marker is a useful and valuable molecular tool to separate male and female pistachios and to determine the genetic diversity among the populations.

The present research aims to study the association and allelic diversity of linked microsatellite markers to grain quality QTLs of 84 exotic rice genotypes. To this end, 9 microsatellite markers (RM540, RM539, RM587, RM527, RM216, RM467, RM3188, RM246, RM5461) were used in which a total of 61 alleles were identified with a mean of 6 alleles per locus. The polymorphism information content (PIC) varied from 0.542 (RM540) to 0.812 (RM3188) for SSR markers. Cluster analysis was performed using UPGMA method and genotypes were divided into five groups. Furthermore, based on regression analysis, for rice grain quality properties in flooding conditions as long as drought stresses, 10 alleles were identified. Of these, four alleles with gelatinization temperature, an allele with protein content under flooding conditions, and three alleles with protein content and three alleles with gelatinization temperature were related under drought stress. It should be noted that the RM216-C and RM5461-D alleles were commonly identified in several traits. The presence of common markers for traits is probably due to the consistency of chromosomal locus controlling these traits or pleiotropy. The results of this study may imply that the important identified alleles for example RM216-A for gelatinization temperature (R2=30.1 %) can be used in rice quality improvement programs.

In order to assess the responses of Hashemi rice genotype and its advanced mutant line under salinity stress of 100 mM Sodium chloride (NaCl) for three and six days the shoot samples were taken for biochemical analysis. This experiment was performed in split plot based on randomized complete block design with three replications. The main factor was factorial combination of saline treatment and sampling period, sub factor included genotypes. The result showed that the chlorophyll content decreased (16.3) under salt stress for the wild type, but higher amount (21.2) in the mutant was recorded. The mutant rice showed higher amount of K+ and lower of Na+ concentrations in shoots under salt stress condition. The results revealed, although the amount of H2O2 of both genotypes was significantly increased by exposure to NaCl, the effect was superior in the wild genotype (44.85). The antioxidant enzymes activity include catalase and peroxidase activity were grow up significantly in advanced mutant line. Also, the level of flavonoids and phenol content under salinity stress were enhanced dramatically in mutant line. In order to evaluate ion homeostasis under salinity stress condition the measurement of osmolytes such as proline, glycine betaine and trehalose indicated the mutant rice by rising the production (4.4, 0.81 and 87.55 respectively) of these metabolites in shoot showed the better tolerance to salinity stress. In conclusion, the observation indicated that mutation had a positive impact on ROS scavenging system and ion homeostasis mechanism and ultimately have led to salt tolerance in the mutant genotype.

To improve Agrobacterium-mediated transformation of tobacco, factors influencing gene delivery, including genotype of the plant, bacterial strain, and Agrobacterium transformation procedure, were tested via direct somatic embryogenesis. Leaf tissue of three different tobacco genotypes (Nicotiana tabacum L. cvs. Samsun, and Xanthi, and N. benthamiana) were used as explant. Leaf explants were transformed using three Agrobacterium tumefaciens strains (EHA105, GV3101, and LBA4404) harboring the binary vector pCAMBIA1304 using three different types of transformation methods as named Agro-inoculation, Agro-infection and Agro-injection. Selection of hygromycin resistant shoots was conducted on MS medium containing 3.0 mgL-1 BAP and 0.2 mgL-1 IAA, 250 mgL-1 cefotaxime and 30 mgL-1 hygromycin. Hygromycin resistant shoots were then rooted on MS medium supplemented with 250 mgL-1 cefotaxime and 15 mgL-1 hygromycin. The results indicated that A. tumefaciens strain LBA4404 was more effective in gene delivery than EHA105 and GV3101 and Agro-infection method proved to be significantly better than two other methods. The highest transformation rate was obtained with the Agrobacterium strain LBA4404 and Agro-infection method with approximately 72.80%, 84.57%, and 93.33% for N. benthamiana, Samsun and Xanthi, respectively. Histochemical GUS assay confirmed the expression of gusA gene in putatively transformed plantlets. PCR and RT-PCR analysis using gene-specific primers confirmed the integration of the gusA and hpt genes and the expression of the gusA and hpt genes, respectively. Furthermore, Southern blot analysis confirmed stable integration of the gusA gene in selected T0 transformants.

The present study was performed to evaluate the effects of different concentrations of ethyl methane sulfonate (0, 0.1, 0.2 and 0.5%) on some physiological characteristics of regenerated plants from calli of stevia at 30, 60 and 120 min under various levels of salinity stress (0, 50 and 100 mM of NaCl). This experiment was carried out based on completely randomized two-factorial designs with three replications. With respect to the result, the regenerated calli became dark and hidden in the medium under exposure time of 120 min, the length of stem regenerated calli was increased under exposure times of 30 and 60 min. Moreover, our data showed that EMS mutagenesis had a significant effect on physiological traits of regenerated stevia under salinity stress at the probability level of 1%. Consequently, the stevia mutants of M10, M11, and M19 showed the highest resistance to different levels of salinity which can be considered as potential samples for further breeding programs.

Bacillus thuringiensis Berliner as a biological control agent can play a crucial role in the integrated management of a wide range of plant pests and diseases. B. thuringiensis is expected to elicit plant defensive response through plant recognition of microbe-associated molecular patterns (MAMPs), however, there is little information on the molecular base of induced systemic resistance priming of tomatoes. Using q-RT-PCR technique, the transcription rate of the genes responsive to salicylic acid, SA (Chi9, Chi3, PR1), jasmonic acid, JA (Pin2), and of the signaling regulatory genes of jasmonate/ ethylene, JA/ ET hormones (WRKY33, ERF1, MYC2) were studied at the time of 6, 12, 24, 48, 72, and 96 hours after inoculation of tomato plants with B. thuringiensis strain IBRC-M 11096 as the promoting plant growth factor. The bacterial strain could prime tomato cultivar of Early Urbana through induction of all three hormonal signaling pathways (SA, JA, and ET) involved in the resistance to a broad range of necrotrophic as well as biotrophic pathogens. However, further transcription of WRKY33, ERF1, MYC2, and Pin2 genes in the inoculated plants, indicated that the observed priming effect was mainly based on JA/ ET signaling pathway. These promising results indicate high potential of superior isolates of B. thuringiensis in the field management of the crops.