In vitro‑derived plants grown from low nitrate medium produced quality tubers in Decalepis hamiltonii Wight & Arn.

In the present study, infuence of nitrate concentration on in vitro rooting and its ex vitro hardened tubers were investigated in
D. hamiltonii. In vitro multiple shoots established on the MS medium were used as explants for this study and concentration
of indole-3-butyric acid (1.23 µM) required for root initiation was determined. The efect of diferent nitrate concentrations
in MS medium for in vitro rooting was investigated and positive (¼ and ½ strength) infuence was observed on 14 days
inoculation. The in vitro rooted plants (IVP) showed 80% survival upon hardening and exhibited similar growth pattern to
seedling plants. The 1-year grew ex vitro hardened plants were evaluated for their tuber quality with reference to their yield
and favor metabolite 2-hydroxy-4-methoxy benzaldehyde (2H4MB) content. The IVP grown from ¼ nitrate strength media
produced 155±4.85 g FW of tuber biomass which is observed to be higher than full nitrate strength IVP (112±2.52 g)
which are grown under similar conditions in the greenhouse. The favor metabolite content, total phenolics, total favonoids,
and antioxidant potential of these IVP tubers were evaluated. Upregulation of favor biosynthetic pathway genes DhPAL,
DhC4H and DhCoMT were observed in tubers of potted plants that developed from low nitrate strength culture media. In
this study, superiority of tissue cultured plants was evident, wherein in vitro plants developed in low nitrate strength medium
and acclimatized could produce a higher yield in tuber biomass and maintain relative content of favor compounds in this
endangered plant