Strategies to overcome explant recalcitrance under in vitro conditions

Plant tissue culture is a powerful tool for the plant production as well as trait improvement. In both the cases, regeneration, either through meristematic tissue or differentiated tissues, is the prerequisite step for further physiological processes. Of course, wide range of plant growth regulators, media, physical factors, plant age, explant type, and season are managed to get the desired organogenesis. Despite such manipulations, some of the plant species, being highly recalcitrant for the tissue culture purposes, failed to initiate organogenesis. In vitro plant recalcitrance includes unresponsiveness to the culture manipulations, loss of totipotency, loss of morphogenetic competence, and difficulties in germination (in the case of seed-mediated regeneration). Free radicals generated due to stress and the status of endogenous concentrations of plant hormones play a significant role in regenerations. For such species to regenerate, different strategies are employed. In the present chapter, the molecular basis of recalcitrance, factors to overcome tissue culture recalcitrance, case studies of such recalcitrant species, and biotechnological interventions to overcome tissue culture recalcitrance have been discussed.