Molybdenum improves water uptake via extensive root morphology, aquaporin expressions and increased ionic concentrations in wheat under drought stress

Abstract Molybdenum (Mo) despite elevating drought tolerance is comparatively little understood with regard to underlying mechanisms involved. We herein investigated the effects of Mo on root morphology, root water uptake, aquaporin (AQP) expressions and mineral nutrient concentrations in winter wheat under polyethylene glycol 6000-simulated drought stress (PSD). Our study firstly demonstrated that nitric oxide (NO) signal was involved in Mo-regulated root growth, mainly reflected in Mo supply and NO donors enhanced root morphology such as lateral root length and root tips due to increased NO production; however, NO scavengers decreased root morphology due to decreased NO production under PSD. The root water uptake rate was enhanced by Mo, which positively correlated with root tips and lateral root length. Mo supply improved AQPs expressions, particularly TaPIPs , suggesting that the improvements of root growth and AQPs expressions were involved in Mo-increased water uptake in wheat root under PSD. Further study showed that Mo application decreased wheat leaf transpiration, but increased root osmotic-adjustment ions K + , Ca 2+ and Mg 2+ concentrations, indicating that root osmotic pressure induced by increased ionic concentrations was the power of Mo-increased water uptake, but not transpirational pull induced by transpiration. This study suggests that Mo improves water uptake via extensive root morphology, AQP expressions and increased ionic concentrations in wheat under drought stress.