DOCTOR OF PHILOSOPHY

Abstract

This work was carried out during 2011- 2015 in the laboratories of Cell Res. Dept. (CRD), Field Crops Res. Institute (FCRI), Agric. Res. Center (ARC), Giza, as well as, in the greenhouse of Horticulture Dept, Fac. of Agric., Ain Shams Uni., Egypt, to study the variation among canola varieties in response to salt tolerance through tissue culture propagation. This work was aimed to establish a regeneration protocol for canola varieties, production of salt-tolerance plants through selection of salt-tolerance callus via somaclonal variation and subsequent regeneration of plantlets from such callus, identifying the genetic variations among the used varieties and the newly developed salt tolerant genotypes produced via somaclonal variation using RAPD and ISSR banding patterns. The important results could be summarized as follow: 1. Selection of the highest and lowest salt tolerant canola varieties Four concentrations of NaCl, i.e. 4000, 8000, 12000 and 16000 ppm as well as the control treatment were used to evaluate the level of salinity tolerance for 22 canola varieties and to choose the most salt-tolerant varieties and most susceptible ones (two genotypes for each group) At the end of the experiment some germination indices correlated to seed vigour were evaluated. Results indicated that germination percentage and germination velocity were significantly affected by all concentrations of NaCl, as well as the germination rate. All studied traits were decreased with increasing salinity concentrations beyond 8000 ppm NaCl, with a sharp drop at 12000 ppm NaCl concentration and prevention of germination of canola seeds at the concentration of 16000 ppm NaCl. All canola varieties were affected significantly by the high salt concentrations. Bingo and Torpe varieties markedly surpassed all varieties concerning to germination percentage and germination velocity traits; meanwhile, Conny and Siberian varieties recorded the lowest values. 2. Establishment of canola regeneration protocol Four canola varieties were selected according to their salinity tolerance: two salt tolerant varieties (Bingo and Torpe) and two salt susceptible ones (Conny and Siberian). Theses varieties were used for establishing a regeneration protocol for canola. 2.1. Callus induction Cotyledon and hypocotyl explants were cultured on MS-medium supplemented with three concentrations of 2,4 dichlorophenoxy acetic acid ( 1.0, 1.5, 2.0 mg/l 2,4-D, as well as, control) to enhance callus initiation. Results showed that 2.0 mg/l 2,4-D concentration was the best medium for cotyledon explants. Torpe variety recorded the highest frequency (89.00% equal to 1.059) followed by Siberian variety (64.00% equal to 1.028). On the other hand, the lowest callus initiation percentage