Iranian Journal of Genetics and Plant Breeding
Volume:1 Issue: 2, Oct 2012

The objectives of the present research were to evaluate the variability induced by gamma-irradiation among a population of M8 sunflower mutant lines and to identify molecular markers associated with different seed germination traits. Experiments were carried out under well watered and water-stressed conditions using a randomized blocks design, with three replications. The studied traits consisted of critical times (the time to starting germination, TSG), the time to 50% germination (T50%G) and the time to maximum germination (TMG) and the percentage of seed germination (PSG). In both conditions, a large genetic variation was observed among mutant lines. Some mutant lines showed higher values of germination parameters when compared with the original lines (AS613). Results revealed the a efficiency of gamma irradiation for inducing genetic variation in sunflower, for germination traits. A highly negative, significant correlation was observed between PSG and the critical times of germination. Mutant line “M6-39-2-1” was significantly superior to the original line, for the studied traits, under the water-stressed condition. Multiple regression analyses showed that some AFLP markers were associated with several traits. The most informative AFLP markers were “E37M62-5” and “E33M60-6” which did not have any interactions with water stress. Several markers were associated with seed germination parameters in both conditions. The markers which were associated with different traits could be used in marker-assisted selection for germination parameters.

Several new superior apricot × plum (Prunus armenica × P. domestica) inter specific hybrid rootstocks have been recently produced in Iran, but the propagation of these hybrids by conventional means has been shown to be very difficult. In vitro propagation could be a reliable method for mass clonal propagation of these new rootstocks. In this study, in vitro establishment, proliferation and rooting of two apricot × plum inter specific hybrid root stocks namely HS405 and HS706 were evaluated. For disinfection, different concentrations of ethanol, sodium hypochlorite and mercuric chloride were tested. The highest number of active buds was obtained from spring season nodal explants in hormone-free WPM medium. Addition of 200 mg/l Na-Cefotaxime or 100 mg/l nano silver had a positive effect on controlling indigenous contaminations. The greatest shoot proliferation was recorded by using 4 mg/l BAP + 0.5 mg/l GA3 supplemented in the WPM medium. Addition of 2 mg/l GA3 to the culture medium improved shoot elongation, significantly. The best results were obtained for rooting when micro shoots were dipped in a 1000 mg/l IBA solution for 20 seconds and cultured on hormone-free WPM.

The present study was carried out to estimate genetic variability parameters for some traits such as pods per plant, cell membrane stability, one thousand kernel weight, flowering period, grain filling period, chlorophyll content, relative water content, leaf excised water content, seed per pod and pod length, in 16 winter rapeseed genotypes. Statistical analysis showed significant differences between the tested genotypes. Genotypic and phenotypic coefficients of variations were high for yield, pods per plant and cell membrane stability. Heritability estimates were high for pods per plant, cell membrane stability, one thousand kernel weight and flowering period. A high genetic gain was observed for pods per plant and cell membrane stability. Correlation analysis showed a significant and negative relationship between the flowering and grain filling period (-0.883) and between cell membrane stability and chlorophyll content (SPAD) (-0.587). A positive and significant correlation was found between the grain yield and relative water content (0.603).

The present investigation was undertaken to describe the relationships among species of Avicenniaceae family which have both economic and medicinal activities, collected in Indian Sundarban by the help of RAPD and ISSR markers. In this study, three different species of Avicennia genus were collected. Frozen young leaves (-200C) were taken to isolate the genomic DNA using a slightly modified CTAB method. For this experiment, a set of 10 RAPD and 10 ISSR markers were used to analyse the genetic diversity. The study showed that ISSR markers were more efficient than RAPD markers for polymorphism detection, polymorphic bands content per primer and total no of loci detection per primer as they were 75.53%, 11.9 and 15.6, for ISSR and 69.04%, 9.6 and 13.7 for RAPD, respectively. However, the observed no of alleles, effective no of alleles, Nei’s (1973) gene diversity and Shannon’s information index (I) were higher for RAPD (1.6087, 1.6087, 0.3043 and 0.4219, respectively) than for ISSR (1.5357, 1.4356, 0.2345 and 0.3357, respectively). However, no such reports on genetic diversity using ISSR markers were available in the genus Avicennia. The results of this study can be seen as a starting point for future researches aimed to develop phylogenetic tree using more samples and more molecular markers.

Regeneration of explants plays a significant role in plant transformation. Explant type, hormonal concentration, and pre-culturing period are important in transformation efficiency. To get an efficient transformation of canola and optimize regeneration conditions, different explants along with different culture media were studied. Four canola varieties were used to evaluate regeneration ability of hypocotyledonary and cotyledonary leaf explants. In addition, cotyledonary leaf explants were evaluated on the MS medium containing five different concentrations of BAP. Suitability of cotyledonary explants in transformation experiment was assayed by an exogenous gene, coding for P5CS, the key enzyme in proline biosynthesis. The transformation of cotyledonary explants through Agrobacterium tumefacience-mediated gene transformation was used in a stepwise increased selection marker manner. PCR and proline content analysis confirmed the success of transformation. Cotyledonary explants displayed a higher regeneration efficiency than hypocotyledonary explants. In addition, BAP at 5 mg/l in the MS medium increased the rate of regeneration. Results showed that pre-culturing explants for 48 h increased the rate of transformation. Assessing the proline concentration further verified the expression and activity of the transformed gene. The P5CS transformed plants were more resistant to salinity compared to the non-transgenic control plants

Immature embryos as a choice tissue for genetic transformation of maize have a few limitations, such as genotype dependence, time-consuming and requiring a well-equipped greenhouse for access, at any time. In the present study, the split-seed explants were used for genetic transformation of maize, B73 line. The transformation of maize split-seed explants from the inbred line B73, for resistance to abiotic stresses was carried out via particle bombardment using pCA-35S-DREB construct, carrying Arabidopsis transcription factor DREB1A under the control of the CaMV 35S promoter and the selectable marker bar. For the optimization of gene-gun transformation parameters, we used two distances, 6 and 9 cm, one or double shooting and pre-treatment culturing of explants. The results showed that double shooting in 9 cm under pre -treatment conditions can improve transient expression of GUS gene in split-seed explants. PCR analysis confirmed the presence of DREB1A and bar genes in one out of 11 transformants. The results showed that split-seeds of B73 line can be used as a suitable explant for maize transformation.