In vitro mass propagation of Murraya koenigii L

• The study for the first time standardized an effective and reproducible in vitro regeneration protocol in Murraya koenigii.
• Shoot tip explants were found highly effective for the large scale in vitro shootlets production.
• An efficient root regeneration protocol has standardized in the shootlets by using in vitro liquid culture technique.
• Developed shootlets were successfully acclimatized by utilizing 70 days acclimatization period.
• The protocol could fruitfully contribute in the in vitro production and conservation of Murraya koenigii.

Present endeavor was carried out for large scale shoots production from shoot tip meristem of Murraya koenigii obtained from mature field-raised plants. Apical shoot buds were cultured onto the MS medium augmented with various concentrations of single cytokinin (TDZ, BA and Kn) or in various combinations with an auxin NAA. Maximum percentage response (79%) with highest number of shoots (30.6 ± 0.11) and shoot length (4.16 ± 0.20 cm) per explant was obtained on MS medium supplemented with TDZ (0.5 μM) + NAA (0.3 μM) after 8 weeks of culture. Shootlets with 3–4 nodes were utilized for in vitro rooting by using filter paper bridge method, and best response (60%) with root number (3.34 ± 0.10) and root length (2.50 ± 0.05 cm) was appraised on 1/2 strength liquid MS medium supplemented with 1.5 μM IBA after 4 weeks of incubation. The well-developed micropropagated plantlets were acclimatized successfully in the culture room for 70 days initially in soilrite under 150 PPFD (4 weeks) followed by transfer onto the mixture of soilrite + garden soil under 300 PPFD (6 weeks). The estimation of photosynthetic pigments (chl a/b and carotenoid content) and photosynthetic rate was found significantly increased after 2 weeks of acclimatization. Similarly, antioxidative enzymes SOD, CAT, APX and GR also showed an increasing trend throughout the hardening period. While contrarily, MDA and H2O2 contents accumulation were found decreasing showing a significant decrease in the internal stress in the plants. Hence, the outcome favors the hypothesis that to minimize the effects of oxidative stress and its products (MDA, H2O2, etc.), plants have evolved a complex ROS scavenging antioxidative enzymatic system. After 70 days acclimatization in culture room, the plants were transplanted to the field in normal garden soil showed good survival rate (80%) without any morphological variations.