Induction of Phytophthora tolerance in rough lemon Citrus jambhiri Lush through tissue culture and mutagenesis

Abstract

The present investigation entitled Induction of Phytophthoratolerance in rough lemon (Citrus jambhiri Lush.) through tissue culture and mutagenesis was carried out at Plant Tissue Culture Laboratory, Division of Fruit Science and Plant Tissue Culture Laboratory, School of Biotechnology in collaboration with Division of Plant Pathology, Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu during 2016 to 2018. newlineIn order to establish in vitro protocols for raising aseptic cultures, leaf, root and epicotyl segments were used as explant material. Among surface sterilization chemical treatment, mercuric chloride (0.1 %) for three minutes gave minimum contamination (19 % in leaf, 24 % in root and 15 % in epicotyl explants) with maximum establishment of cultures. Maximum callus induction (98.46 %) was observed in epicotyl segments on Murashige and Skoog (MS) medium supplemented with 2,4-D (1.0 mg/l) whereas, maximum callus induction (95.41 %) in leaf segments was observed on MS medium containing 2,4-D (3.0 mg/l). Callus raised from epicotyl and leaf segments showed maximum regeneration of 82.19 per cent and 68.79 per cent, respectively on MS medium supplemented with BAP (3.0 mg/l). However, callus from root segments did not regenerate. Effect of increasing age of callus was also studied which showed that callus retained regeneration capacity (3.55 %) even after 210 days of culture. Rooting percentage was observed maximum in shoots regenerated from leaf segment callus (96.00 %) and in shoots regenerated from epicotyl segment callus (95.00 %) on half strength MS medium containing NAA (2.0 mg/l). newlineFor in vitro mutagenesis, leaf and epicotyl derived calli were used as explant material. The alkylating agent methyl methane sulphonate (MMS) and ethyl methane sulphonate (EMS) at 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6%, were used for mutagenesis. LD50, the dose required for selection of tolerant calli corresponded to 0.4 per cent each for MMS and EMS treatments. The mutagenic calli which survived at e