An efficient system for plant regeneration of Senna occidentalis from hypocotyl-derived callus was developed. Callus was induced from leaf and hypocotyl explants on MS medium amended with 9.04 μM 2,4-D + 2.22 μM BAP and 10.74 μM NAA + 2.22 μM BAP. Medium browning due to leaching of compounds from callus was encountered and ameliorated through incorporation of 2.84 μM ascorbic acid. Leaf-derived callus showed no shoot induction ability, while hypocotyl-derived callus produced shoots in all cytokinin-amended treatments and also in combination with 2.68 μM NAA. For shoot formation, BAP-augmented treatments were better than medium with Kin added. Rhizogenesis was better on 1/2 MS basal medium with IBA than in the NAA and IAA treatments. Regenerated plants were acclimatized with 94% survival and showed similar morphology to field-grown plants.
Rare and endemic plant species represent important components of plant biodiversity which require protection to ensure their sustainable conservation. Cerastium banaticum (Rochel) Heuff. is such an endemic and rare species from Romania, for which the genetic variability of two natural populations was studied by SSR markers. Shannon’s information index revealed low levels of genetic diversity in both populations (I = 0.296). As the first attempt in a conservation program a reproducible micropropagation protocol was established starting from seeds, followed by multiplication, rooting, and ex vitro acclimatization. Among the various plant growth regulators tested the highest multiplication coefficient was achieved on a culture medium with 0.5 mg L-1 6-furfurylaminopurine (K) and 1 mg L-1 α-naphthaleneacetic acid (NAA). On this PGRs concentration a number of 26.6 shoots/individual explant with a mean length of 7.9 cm for new generated shoots was registered. The highest number of roots/individual initiated shoot was 2.6 and it was recorded on a culture medium with 0.5 mg L-1 2-isopentyl-adenine (2iP) and 0.1 mg L-1 NAA. The outdoor acclimatization was successfully performed in a specially designed rocky area in the ‘Alexandru Borza’ Botanical Garden, Cluj-Napoca (Romania).