[Genetic improvement of some genotypes of durum wheat (Triticum durum) using physical and chemical mutagens]

The study was conducted in Abu Jarash farm at the faculty of agriculture, Damascus University in the seasons of 2010/2011 and 2011/2012, by using Augmented RCBD design. The response of three varieties of durum wheat (Douma 1, Cham 5, Bouhouth 9) to two types of Mutagens [physical (gamma rays ɣ), chemical (ethylene amin EI, Dai Etil sulfate DES) and the combined treatment between them (EI + ɣ) and (DES + ɣ) in the lowest dose and concentration] was investigated in order to study the effect of these mutagens on the growth and development of plants, and in the chromosomal aberration in the first generation M1, to calculate and determine the percentage of total and relative changes, and to select and evaluate and characterize the qualitative and quantitative changes (Morpho - physiological, colorimetric, sterile) in the plants of second generation M2, in addition to study the correlations between traits, and determination of the genetic changes by using molecular biology techniques that depends on PCR. The results showed presence of significant genetic variation in response of the studied varieties to the doses and concentrations of mutagens. Bouhouth 9 was superior in the average of chromosomal changes (21.64%) compared with Cham5 (16.62%) and Douma 1 (12.67%), it was observed that-by increasing the doses/concentrations of physical and chemical mutagens the laboratory germination percentage was declined, and the chromosomal changes increased. Bouhouth 9 was also superior in the total changes (17.28%) on Cham5 (15.13%) and Douma1 (12.60%), the total qualitative changes was 14 type of change appeared alternatively between the studied varieties, where the low and moderate doses and concentrations have played a positive role to get a useful qualitative changes in the second generation M2 (such as early maturity, short plants, tall Spikes. etc). In the first generation M1, Bouhouth 9 was superior in average of spike length (6.69 cm), number of grains (231.64 grain / plant) and the weight of grain (14.39 g) in the plant, the weight of a thousand grain (62.43 g) compared with the studied varieties, while Cham5 was superior in the average number of total tillers per plant (11.44, 9.16 tiller respectively), and length of stem (94.48 cm) and plant height (100.69 cm). In the second generation M2 also Bouhouth 9 was superior in the number of fertile tillers (7.34 tiller), number of grains (239.89 grain / plant) and the weight of grains (12.29 g) in the plant, the weight of a thousand grain (57.74 g), while Cham5 was superior in the number of total tillers (10.73 tiller), and spike length, stem and plant height (6.01, 82.96, 88.97 cm respectively), Douma1 did not surpass in any of the studied traits compared with the other varieties in the two generations. The combination between treatments have played in some cases a positive role in increasing some studied traits in some varieties, and in both generations (doses and low concentrations of ɣ and DES for the number and weight of grains per plant in the first and second generations, and high concentrations of EI in the varieties Douma1 and Cham5 in the first generation). But those combined treatment have a negative role to other qualitatives and decreased them to the minimal levels in the other varieties (low concentrations of EI in the second generation). The molecular study aimed to detect the variations in the drought genes which form the protein Dehydrin (Dehydrin gene). The DNA of the treatments were amplified by using 12 pair of specific primers for Dehydrin genes (loci) by PCR. The results showed different DNA amplicons for each primer in each treatment, those variations reflected the presence of different locus for each Dehydrin gene in those treatments. Study of variations evaluation for Dehydrin gene have showed a clear difference between the studied treatments. The variations in the molecular weight between locus per gene were very great in some cases, and in other cases it was at a high degree of symmetry, and it was easily distinguished on 4% agarose gel. the PCR results for the Dehydrin genes Dhn1, Dhn6, Dhn10 and Dhn3 showed a monomorphic pattern in most of the studied treatments, and for the Dhn12 a unique pattern was found in one treatment (moderate concentration of DES in Bouhouth9). Dhn2 showed seven patterns, while the genes Dhn4, Dhn8 and Dhn11 showed five patterns, and the Dhn7 showed four patterns, and finally Dhn9 showed three patterns. The Dhn11 was superior in the number of polymorphic patterns, where the number of total patterns was 46 patterns in all treatments, and the Dhn12 has showed lowest number of patterns with only monomorphic pattern. While the Dhn5 didn't show any patterns in all cases. The treatment (ɣ 25 kr) in Bouhouth9 showed the largest number of patterns in the Dhn genes with 18 patterns, and the treatment (DES 0.05%) in Douma1 has showed the lowest number with 10 patterns. It was also noticed that the short-stem trait was absent in the control, while this trait was present in low concentration ethylene amin (EI) treatment with the variety Bouhouth 9.