THAKUR, SANJEEVRANA, SABINA2019-07-242019-07-242019-05http://krishikosh.egranth.ac.in/handle/1/5810116537ABSTRACT In the present investigations,in vitro regeneration of commercially importantSalix sp. was carried out and an attempt was made for in vitro selection of this species against Cytospora along with molecular studies. Indirect organogenesis form leaf and inter nodal segment was achieved. Treatment of 12.5% NaOCl for 10 minutes to both explants along with 0.2% bavistin was found to be the best as it gave maximum number of uncontaminated cultures and per cent survival. Callus was induced from leaf and inter nodal explant on MS medium supplemented with 0.5 mg/l NAA with 1.5 mg/l BA and 0.5 mg/l NAA with 0.5 mg/l BA respectively. Highest percentage of callus was obtained from leaf (96.67%) explants followed by inter nodal segment (93.34%). Percent shoot induction from leaf and inter nodal segment derived calli on 0.5 mg/l BA, 0.50 mg/l Kinetin with 0.25 mg/l GA3 and 0.5 mg/l BA with 0.25 mg/l GA3 was 83.33% and 75.00% respectively. Leaf explants was found to be most responsive explants for indirect regeneration. Highest multiplication rate (1:4) was obtained on MS medium fortified with 1.50 mg/l BA with 0.25 mg/l GA3. Shoot number was elevated with the increase in subculturing passages upto third passage thereafter there had been a decline in it. Activated charcoal brings about elongation of shoots. The regenerated shoots were rooted in half strength MS medium containing 500 mg/l activated charcoal. During hardening it was observed that plantlets showed highest survival of 30% in a potting mixture containing sand, soil and cocopeat. To carry out in vitro selection for resistance development, the isolation of canker causing pathogen was done. On the basis of morphological features and BLASTn analysis of ITS region of pathogen, it was identified as Cytospora chrysosperma. The optimum concentration of fungal culture filtrate for selection against canker disease was 30.00 per cent resulting in 12.96 per cent survival of calli. However no shoots were regenerated after selection of calli. For molecular characterization dendrograms were generated to assess the variations among mother plant, control calli and 30 per cent FCF treated calli, using RAPD and ISSR markers which separated them in two clusters where mother plant and control plant always fall in one cluster showing 70 and 79 percent similarity with each other while the selected variants clustered randomly suggesting genetic variation with mother plant, control plant and within the variants.ennullThesis