CALLOGENESIS AND PLANT REGENERATION FROM LEAF EXPLANTS OF CITRUS CULTIVARS.

We have established an efficient protocol for in vitro callogenesis from leaf explants of Troyer citrange (Poncirus trifoliata x Citrus sinensis) and Feutrell's early (C. reticulata x C. sinensis) using modified MS medium enriched with varied concentrations of 2,4-Dichlorophenoxy acetic acid (2,4-D), Naphthalene acetic acid (NAA) and Benzylaminopurine (BAP). Indirect shoot organogenesis was also achieved from leaf derived calli on medium comprising varied concentrations of BAP, Kinetin (KN) and NAA. Best interaction for callus induction was observed by Troyer citrange with modified MS medium containing 0.5 mg L^-1 2,4-D, 0.5 mg L^-1 NAA and 0.5 mg L^-1 BAP, which resulted in 99.66% of leaf segments producing calli within 16.33 days. Morphological differences were also noticed for calli texture and color with different concentrations of 2,4-D, NAA and BAP used. Compact and hard calli were noticed on MS medium with 0.1 mg L^-1 NAA and 0.5 mg L^-1 BAP however, medium including 1.0 mg L^-1 2,4-D, 0.9 mg L^-1 NAA and 0.5 mg L^-1 BAP resulted in friable and smooth calli by both cultivars. Exuberant shoot regeneration response (65.33%) with an average of 6.2 shoots/calli was recorded on MS medium with 2 mg L^-1 BAP and 0.5 mg L^-1 NAA by Feutrell's early. Our findings are the pre-requisite for various biotechnological tools like mutation breeding, somaclonal variations, genetic transformation and somatic hybridization which may be helpful in citrus varietal improvement. [ABSTRACT FROM AUTHOR]