Long-term in vitro culture affects phenotypic plasticity of Neoregelia johannis plants

Abstract

Factors such as stress and prolonged in vitro culture may lead microplants to senescence, reducing and/or altering their morphogenic potential. Considering that plants phenotypic plasticity is improved under stress, this research investigated this physiological event in Neoregelia johannis microplants in long-term in vitro culture. Histological and histochemical analyses were done to monitor the morphogenic potential during the propagules induction by microplants in vitro for 1 and 5 years, and from young leaf used as explants from five subcultures of microplants in both origins. During the monitor of morphogenic pathways, have not been seen alteration for the axillary meristems establishment and development besides that, the microplants multiplication have shown parenchyma cells in the proximal and in shoot bases acting as a pluripotent cell niche to direct adventitious organogenesis (adventitious buds) for young and older cultures. These events were evidenced by amyloplasts and polysaccharides in shoot bases and its reduction along the subcultures to induce adventitious and axillary buds. The culture medium renewal induced stress in microplants as well as the probable aging in older microplants, and it conducted the epidermal and subepidermal cells of older leaves to act as target cells niches for pluripotency and totipotency from the second subculture of leaf explants. All the adventitious roots were originated directly from the meristematic activity of procambial cells and older microplants roots acquired competence to indirect somatic embryogenesis after the second foliar subculture. Therefore, our results indicates that long-term in vitro culture supports new morphogenic competence in microplants, resulting from cell and phenotypic plasticity, that could help in the species survival. Long-term in vitro culture acquired in microplants new morphogenic competences due to the stress caused by the culture medium renewal and its probable aging, resulting to cell and phenotypic plasticity.