Evaluación del efecto de tres condiciones de cultivo in vitro en la calidad de plántulas de caña de azúcar propagadas en Biorreactores de Inmersión Temporal.

Structural and functional deficiencies that affect survival during acclimatization are present in micropropagated plants. The current study was carried out to determine the effect of three in vitro culture conditions (autotrophic, mixotrophic and moderate mixotrophic) on the morpho-physiological and biochemical behavior of plantlets of sugar cane propagated in Temporary Immersion Bioreactors (BIT). Morphological and physiological indicators and key enzymes of carbon metabolism were evaluated. Plantlets that were subjected to autotrophic conditions did not survive due to the stress caused by the absence of sucrose in the culture medium. For this reason they could not be evaluated. The best results were obtained for the condition of moderate mixotrophic. In this case, the morphological variables, height of the plants, fresh weight and dry weight, responded positively. The net photosynthesis response in vitro was minimal and increased notably from the second week of acclimatization. Plants with mixotrophic growth showed very high values of transpiration and stomatic conductance at the beginning of the elongation and during the first week of acclimatization. This group of plants took a longer time than the rest in achieving the control of the loss of water and in reaching a functional stability. Plants that showed a bigger activity of pyruvate kinase were those coming from mixotrophic conditions. An inverse behavior was observed in the phosphoenolpyruvate carboxylase. The activities of syntase sucrose and the neutral invertase were superior for the mixotrophic conditions. [ABSTRACT FROM AUTHOR]