Impact of strong correlations observed in sugarcane responses to sodium chloride and mannitol within temporary immersion bioreactors

Abstract

Sugarcane is a vital crop in tropical and subtropical regions worldwide, contributing to economic growth, energy production, and nutritional value. Over the past decade, numerous studies have demonstrated that in vitro screening for stress tolerance enables rapid evaluation of many plants, propagules, and explants for desirable traits, significantly accelerating the breeding process compared to traditional field methods. This report showcases the correlation between responses to NaCl (salinity) and mannitol (drought) in sugarcane plantlets micropropagated in temporary immersion bioreactors. With coefficients of determination (R2) exceeding 90%, the strongest correlations between sugarcane responses to salinity and drought were observed in the following indicators: shoot multiplication rate (90%), fresh weight of shoot clusters (97%), and levels of malondialdehydes (95%), other aldehydes (98%), carotenoids (95%), and soluble phenolics in the plantlets (96%). Soluble phenolics excreted into the culture medium showed an R2 of 86%, and chlorophyll a had an R2 of 78%. In contrast, chlorophyll b levels and cell wall-linked phenolics exhibited very low coefficients of determination (less than 25%). These findings highlight the strong physiological and biochemical responses of sugarcane to salinity and drought, particularly through phenolic metabolism and oxidative stress markers. The high coefficients of determination indicate reliable predictive relationships, suggesting that these indicators can serve as valuable biomarkers for stress tolerance. In contrast, the weak correlations observed in chlorophyll b and cell wall-linked phenolics underscore their limited relevance in assessing sugarcane resilience under these conditions.