Critical responses to nutrient deprivation: A comprehensive review on the role of ROS and RNS

Reactive Oxygen Species (ROS) and Reactive Nitrogen Species (RNS) are central regulators of plant performance and adaptation to a changing environment. In this sense, increasing evidence points to a prominent role of ROS and RNS in coping with changes in nutrient availability (either deficiency or excess). However, decoding of ROS and RNS signatures into specific nutrient responses still remains a mystery. Thus far, it is known that nutrient deficiencies result in high levels of ROS and exert profound effects on the antioxidant cell machinery. ROS signal propagation relies, in part, on the activation of an array of transmembrane transport systems at the plasma membrane. The intracellular ROS signal leads to the upregulation of adaptation mechanisms (involving activation or de novo synthesis of proteins). Unlike ROS, RNS production under nutrient stress is a much less understood process. Nevertheless, RNS, and NO in particular, intensify the antioxidant responses through the stimulation of their respective scavengers which is helpful for minimizing oxidative damage that can occur during nutrient stress. In the present review, we summarize the current state in the field of ROS and RNS signaling in plant nutrition and identify the main gaps in our knowledge, which should be filled in the forthcoming years. Further understanding of the ROS and RNS signaling cascades is pivotal for improving crop function within a context of limited nutrient resources and harsher climatological conditions.