Influence of culture media and growth hormones on in vitro propagation of Adinandra griffithii Dyer., a critically endangered and endemic plant from northeast India

An effective and reliable in vitro plant regeneration method has been established for Adinandra griffithii Dyer., a critically endangered species which is endemic to Northeast India. This study presents the first successful micropropagation protocol for the Pentaphylaceae family in India. The axenic cultures were established through in vitro seed germination. Seeds inoculated in Woody Plant Medium showed better germination percentage (94%) compared to the seeds inoculated in Murashige and Skoog Medium (66.8%) with an average number of 9.4 ± 0.21^a seeds in WPM and 6.68 ± 0.18^b seeds in MS Medium. The highest shoot proliferation of 8.0 ± 0.26^a shoots per explant with 2.59 ± 0.06^a cm mean shoot length was recorded in WPM supplemented with 6-BAP at 6 mg L^-1. The best results for in vitro rooting were obtained from WPM augmented with IBA at 1 mg L^-1 where 14.5 ± 0.72^a roots per shoot were formed with an average root length of 1.27 ± 0.07^a cm. The in vitro raised plants were successfully acclimatized in greenhouse and transferred to field with 70% survival rate. The healthy acclimatized plants were reintroduced in different Northeastern states like Meghalaya and Nagaland. The protocol developed is beneficial for ex situ conservation of germplasm and mass production of A. griffithii plants.