Conspectus on endangered carnivorous pitcher plant Nepenthes khasiana Hook.f. emphasizing in-vitro regeneration, pitcher development, and stability in genetic makeup

Development of pitchers is the key ornamental feature of carnivorous endemic Nepenthes khasiana Hook.f. As the modification of leaves leads to pitcher formation, the current study focused on in-vitro pitcher formation and comparing the application of natural cytokinin, 2-iP for the first time than other cytokinins in optimizing an effective regeneration protocol with genetic stability. The results showed optimum seed germination (90.67 +/- 1.02)%, highest shoot and leaf proliferation after 28 days at 1/2 MS media fortified with GA3 (0.5 mg/ L), chronological in-vitro laminar modification to basal pitchers correlating ontogenic obliteration and reappearance of carnivory. 2-iP (2.0 mg/L) showed highest regeneration frequency 83.33%, number of shoots (8.85 +/- 1.19), length (9.10 +/- 1.73) cm, leaf number (10.15 +/- 1.96), and length (9.15 +/- 1.96) cm per nodal explant whereas in-vitro raised axillary buds produced highest regeneration frequency 93.33%, leaf numbers (12.12 +/- 1.60), length (13.35 +/- 1.15) cm, root number (9.10 +/- 0.67) and length (8.60 +/- 0.45) cm at 2-iP (2) + IBA (0.5) mg/L. The optimum callusing 50.00 +/- 1.52%, number and length of shoots (6.35 +/- 0.46), (9.60 +/- 1.21) cm were produced at 2-iP (1.5) + 2,4-D (0.5) mg/L. The nodal shoots supplemented with NAA at 3 mg/L produced the highest number of roots (11.25 +/- 1.33) and length (8.45 +/- 1.12) cm while callus-mediated shoots achieved highest root no 7.05 +/- 1.41 and length 4.81 +/- 0.43 cm at 2.5 mg/L NAA and 3 mg/L IAA respectively. The regenerates showed 95% survival and polymorphism 9.09% with 5 SCoT and 5.88% with 5 ISSR primers. Application of 2-iP enhanced production of ornamental quality planting materials through modifications of leaves and basal pitchers highlighting ontogeny of carnivory and endemism. (c) 2024 SAAB. Published by Elsevier B.V. All rights reserved.