Root Form and Function in Plant as an Adaptation to Changing Climate

Abstract

Climate variables including temperature, atmosphere CO2, and precipitation are expected to change during this century. As consequence, in the short- and long-term, the increase of soil temperature, salinity, drought, and waterlogging stresses could be the more exceeding problems for agricultural productivity and the functioning of the natural ecosystems. Root system represents the first and more sensitive target of the climate change, being seriously damaged in its form and function, and consequently strongly contributes to limit plant growth, development and crop productivity. This review focuses on changes of root morphology, architecture, distribution and dynamics, and on essential root physiological processes, such as water and nutrient uptake in response to soil warming, salinity, drought, and waterlogging. The literature appear sometimes to be controversial due to the complexity of root system characterized by different root types, genetically, developmentally, and functionally distinct, and by diverse root morphological parameters such as total root length, biomass, specific root length (SRL), and tissue density and fineness differently involved on root stress responses. For example, the change on total root length and dry weight, the lateral root formation, the depth of rooting and the root dynamics represent the preferential strategy for plant species in water-limited environments. Whereas, the development of aerenchyma, tissue containing enlarged gas spaces with a low-resistance pathway to oxygen, often accompanied by the aerotropic and extensive lateral roots formation, the herringbone-type root architecture, the emergence of adventitious roots and the presence of anatomical barriers are expressed in flooded root. Salinity reduces plant growth and yield by two mechanisms, osmotic stress and ion cytotoxicity. It is difficult to separate the osmotic effect from specific ion effects that overlap during the development of salinity stress, thereby some uncertainty exists regarding the relative importance of both mechanisms. The responses of root cells are finalized to maintain their own correct functionality, despite the condition of elevated Na+ concentration. The genetic diversity of the root system in the plant response to climate change was also reported.