Journal of Plant Molecular Breeding
Volume:2 Issue: 1, Winter and Spring 2014

Fusarium wilt caused by Fusarium oxysporum f.sp. Lycopersici is one of the major obstacles to the production of tomato which causes huge losses in tomato products worldwide. In order to increase the tolerance to this disease, a triple structure containing PR1, chitinase and glucanase genes controlled by 35S promoter was transferred to tomato. Eight days after planting on pre-culture medium, explants were inoculated by Agrobacterium tumefaciens strain LBA4404 containing the aforementioned plasmid. When the regenerated shoots grew to 2-3 cm, they were cut and transferred to rooting medium.The plantlets were then transferred to pots filled with a soil mixture of peat moss and perlite for further acclimatization. The putative transgenic plant lines were analyzed by multiplex PCR and the transcription of the transgenes was confirmed by RT-PCR method using the specific primers. The estimated value for the frequency of the simultaneous transfer of chitinase, glucanase and PR1 genes to tomato was 2.7%. Protein extracts of transgenic plants expressing chitinase, glucanase and PR1 genes inhibited in vitro hyphal growth of F. oxysporum f.sp. lycopersici. Compared with non-transgenic control plants, despite some alterations in chlorophyll content no other morphological changes were observed in transgenic plants. The total content of chlorophyll “a” and “b” in transgenic plants were 31.8 and 36.2 % higher than that of control plants, respectively, which may be attributed to metabolic changes due to simultaneous expression of three transgenes.

Codon bias refers to the differences in the frequency of occurrence of synonymous codons in coding DNA. Pattern of codon and optimum codon utilization is significantly different between the lives. This difference is due to the long term function of natural selection and evolution process. Genetics drift, mutation and regulation of gene expression are the main reasons for codon bias. In this study, the codon bias analysis was done on photosynthesis and respiratory related genes of phosphoenolpyruvate carboxylase (PEPC), NADP-malic enzyme (NADP-ME), pyruvate orthophosphate dikinase (PPDK), glycerate kinase (GK) (nuclear genes), rubisco, NADH-dehydrogenase subunit F and cytochrome-C (chloroplast genes) from Aeluropus littoralis plant. Nuclear gene sequences were obtained after partial isolation and for chloroplast genes obtained from nucleotide database. Calculation of codon adaptation index (CAI) showed that studied genes with direct or indirect association with photosynthesis, had high level of gene expression and had also a tendency to optimum codon utilization. The results also showed the difference in codon bias between genes encoded in nucleus and chloroplast for some amino acids.

Conventional methods of pear breeding, largely based on intra- and inter-specific hybridization, are difficult because pear is highly heterozygous, polygenic and has a long juvenile period. Genetic improvements of pear cultivars are possible through induction of mutations and gene transfer by genetic engineering. A general prerequisite for these approaches is to establish an efficient plant regeneration system. In the present study, the effect of two basal media (MS and NN) and different concentrations of TDZ (0, 2.5, 5, 7.5 μM) or BAP (0, 4, 8, 16 μM) in combination with NAA (1 μM) on direct shoot regeneration of two pear (Pyrus communis L.) genotypes 'Bartlett' and 'Dargazi' was investigated. The obtained results showed that 'Dargazi' had higher rates of shoot regeneration than 'Bartlett' and in both cultivars the highest percent of shoot regeneration was observed from lower sections of the leaves. Although the highest percent of shoot regeneration in 'Bartlett' (38%) was attained in the NN medium containing 2.5 µM TDZ and 1 µM NAA, the differences in shoot regeneration between this medium and the NN media containing 5 or 7.5 µM TDZ and 1 µM NAA were not significant. The highest percent of shoot regeneration in 'Dargazi' (56%) was obtained in NN medium containing 7.5 µm TDZ and 1 µm NAA. It can be concluded that genotypes, explant types and culture media composition could effect on direct shoot regeneration of pear.

Seed protein quality is an important topic in the production of soybean. The quality of soybean proteins is limited by anti-nutrient proteins and low levels of essential sulfur amino acids. In this study, protein content and solubility of six cultivars were evaluated and seed storage proteins were analyzed using SDS-PAGE and scanning densitometry. The results showed that seed storage protein bands were similar among soybean cultivars. However, concentration of β-conglycinin (7S), glycinin (11S) proteins and related subunits were statistically different among the soybean cultivars. According to the results of this study, 033 and DPX cultivars were characterized by high levels of protein content (42.45 %) and protein solubility (76.58 mg g-1) respectively. Two cultivars DPX and JK were also identified by high 11S/7S ratio (1.39 and 1.43 % respectively). Besides, the JK was considered by the lowest concentration of 7S protein (20.35 %). The results showed that a significant negative correlation existed between protein content and solubility (r= -0.66). A significant and moderate positive correlation was found between acidic and basic subunits with 11S protein (r= 0.72 and 0.47 respectively). The 11S and 7S proteins also showed positive and negative correlation with 11S/7S ratio (r= 0.70 and -0.85 respectively). On the other hand, acidic subunits were characterized by significant positive and negative relationship with 11S/7S ratio and some anti-nutrients protein respectively. Thereupon, these results suggested that the development of new genotypes of soybean with high level of acidic subunits of 11S protein can be notable in increasing seed storage protein quality in soybean breeding programs.

A complete diallel cross of nine cotton genotypes (Gossypium hirsutum L. & Gossypium barbadense L.) viz Delinter, Sindose-80, Omoumi, Bulgare-539, Termez-14, Red leaf (Native species), B-557, Brown fiber and Siokra-324 having diverse genetic origins was conducted over two years to determine the potential for the improvement of yield, its components, oil and fiber quality traits by means of genetic analysis, combining ability, heritability and heterotic effects. The detailed studies were based on F1 generations where crossed seeds in the first year were used for F1 generation in the second year. The successful hybrids were recognized and distinguished by morphological markers such as flower color, spot position and their colors in petal, fiber color, seed linter, leaf color and their shapes. Analysis of variance for Simple Square Lattice Design (SSLD) showed highly significant differences (P ≤ 0.01) among various genotypes which allowed genetic analysis by Griffing, Hayman and Hayman-Jinks, method. Additive- dominance model and related correlation (Wr, Vr) were adequate for majority of the traits and partially adequate for some traits. Majority of the traits were influenced by non-additive gene action in F1 generation. These results are encouraging for practical improvement through hybrid breeding programs and the contributions of additive genes through selection method. Significant variation for general combining ability (GCA) effects, specific combining ability (SCA) effects (P ≤ 0.05) and high narrow sense heritability indicates the potential for improvement through selection. On the other hand, over-dominance gene action, low and moderate rate of narrow-sense heritability for some traits suggests that improvements should be made utilizing a combination and hybrid breeding approach.

Iron is one of the most important nutrients in the human diet. According to the high consumption of staple foods such as wheat, the deficiency of iron in these crops would lead to nutritional disorders and related complications. To identify microsatellite markers associated with wheat grain iron content,38Iranian prevalent wheat genotypes were assessed using 30 pairs of genomic and EST microsatellite markers. Based on field experiments, significant difference was observed among studied genotypes for grain iron content which ranged from 34-53 mg/Kg. in the molecular experiment, the range of alleles per SSR locus was 2-9 with a mean of 4.5 and the mean of polymorphism information content (PIC) was 0.55. The stepwise regression analysis has been used for estimating the relationship between microsatellite markers and grain iron content. The results indicated that Xwmc617 (4A, 4B, 4D), Xgwm160 (4A) and Xbarc146 (6D,6B,6A) were significantly correlated with wheat grain iron content. The results of this research can be used in further studies and marker assisted breeding of wheat to increase grain iron content.

In this study, genetic diversity of 20 wheat genotypes was evaluated using 126 simple sequence repeats (SSR) alleles, covering all three wheat genomes. A total of 1557 allelic variants were detected for 126 SSR loci. The number of alleles per locus ranged from 4 to 19 and the allelic polymorphism information content (PIC) varied from 0.66 (Xgwm429) to 0.94 (Xgwm212 and Xgwm515). The high­est polymorphism was observed in Xgwm212 and Xgwm515 primerswith 19 alleles, while the lowest polymorphism belonged to Xgwm429 with 4 alleles. The highest number of alleles per locus was detected in the genome A with 594, compared to 552 and 411 for B and D genomes, respectively. Dendrogram was constructed using Dice similarity coefficient and UPGMA algorithm by NTSYSpc2.0 software and genotypes were grouped in to six clusters. The knowledge about the genetic relationships of genotypes provides useful information to address breeding programs and germplasm resource management. This study also confirms the usefulness of SSR markers to study wheat genetic diversity.