Osmoregulators’ accumulation minimizes the effects of drought stress in sugarcane and contributes to the recovery of photochemical efficiency in photosystem II after rewatering

Abstract

Drought is the main yield limiting factor in most sugarcane crops worldwide. This study aimed to assess the relationship between osmoregulators, photochemical efficiency of photosystem II (PSII), and regulation of electron transport rate (ETR) in sugarcane varieties under drought stress and rewatering. The experiment was conducted in pots, with two sugarcane varieties, RB72454 and RB92579. At 105 days after planting, plants were submitted to irrigation (control) and no irrigation (drought stress), followed by rewatering. The RB72454 variety was the most sensitive to drought stress, with low proline (Pro) accumulation, no change in glycine betaine (GB) concentrations, and greater electrolyte leakage (EL). High photochemical damage was also observed in PSII, including further reductions in maximum (Fv/Fm) and effective quantum efficiencies of photosystem II (ΦPSII). Drought also reduced ETR and increased non-photochemical quenching (qN), which may have contributed to delaying recovery of the RB72454 variety after rewatering. When the RB92579 variety was subjected to drought stress, it presented higher Pro and GB accumulation, lower EL and photoinhibition and small declines in Fv/Fm, ETR and ΦPSII, and slight qN increase. This resulted in less damage to the PSII photosynthetic apparatus under drought stress and contributed to maintaining cell turgidity and protecting the membrane structures of RB92579 variety chloroplasts. In addition, osmoregulators’ accumulation persisted in the RB92579 variety after rewatering, allowing for faster recovery after stress.