In vitro response of sugarcane (Saccharum spp. Hybrid) plantlets to flooding stress

Flooding caused by climate change puts the productivity of sugarcane cultivation at risk. The objective of this study was to evaluate the effect of in vitro flooding stress on sugarcane plantlets. Sugarcane plantlets were grown in test tubes containing Murashige and Skoog semi-solid medium without growth regulators as a control treatment and two stress levels using a double layer with sterile distilled water to simulate hypoxia and anoxia. After 15 d of culture, the number of new shoots, plantlet height, number of leaves, number of roots, root length, stomatal density, percentage of closed stomata and percentage of dry matter were evaluated. In addition, biochemical variables such as chlorophylls, carotenoids, phosphoenolpyruvate (PEP), Rubisco, total proteins (TP), proline (Pr), glycine-betaine (GB), phenols, antioxidant capacity and lipid peroxidation were determined in all treatments. Results showed a higher number of new shoots, leaves and percentage of closed stomata in the flooded plantlets, while plantlet height, number of roots, stomatal density, and dry matter were higher in the control treatment. Regarding, chlorophyll, carotenoid, PEP and Rubisco contents decreased in the flooded treatments, while TP and phenol contents were higher in the partially submerged treatment. Antioxidant capacity and lipid peroxidation increased in the fully submerged treatment. Pr and GB contents did not show changes in any of the evaluated treatments. Stress induced by excess water in a double layer in vitro is an alternative method to determining physiological and biochemical mechanisms of tolerance to hypoxia and anoxia caused by flooding for breeding programs in sugarcane.