Integrating Classical with Emerging Concepts for Better Understanding of Salinity Stress Tolerance Mechanisms in Rice

Abstract

Rice is an important cereal crop responsible for world's food security. The sensitivity of rice plants toward a range of abiotic stresses is a prime challenge for its overall growth and productivity. Among these, salinity is a major stress which results in a significant loss of global rice yield annually. For finding straightforward and strict future solutions in order to assure the food security to growing world population, understanding of the various mechanisms responsible for salt stress tolerance in rice is of paramount importance. In classical studies, identification of salt tolerant cultivars and the genetic markers linked to salt tolerance and breeding approaches have been given emphasis. It further affirmed on the identification of various pathways regulating the complex process of salt stress adaptation. However, only limited success has been achieved in these approaches as salt tolerance is a complex process and is governed by multiple factors. Hence, for better understanding of salt tolerance mechanisms, a comprehensive approach involving physiological, biochemical and molecular studies is much warranted. Modern experimental and genetic resources have provided a momentum in this direction and have provided molecular insights into different salt stress responsive pathways at the signaling and regulatory level. The integrative knowledge of classical and modern research of the understanding of salt stress adaptive pathways can help the researchers for designing effective strategies to fight against salt stress. Hence, the present review is focused on the understanding of the salt stress tolerance mechanisms in rice through the consolidative knowledge of classical and modern concepts. It further highlights the emerging new trends of salt stress adaptive pathways in rice.

Brassinosteroids: A Promising Option in Deciphering Remedial Strategies for Abiotic Stress Tolerance in Rice

“…Rice is an important food crop, produced in many countries worldwide and feeding significant portions of the global population ( IRRI, 2006 ; Kaur and Pati, 2017 ). More than half of the world’s population acquires 80% of their calories from rice ( FAO, 2008 ).…”

Abiotic Stress Responses in Plants: Current Knowledge and Future Prospects

“…Plant cells can sense changing environmental signals leading to significant changes in their physiology, metabolism, and gene expression [12,13]. The stress stimuli are first perceived at the level of cellular membranes that initiates a cascade of events to transmit the signal to various organelles thus activating the appropriate molecular network [21]. In plants, the primary cell wall is composed of cellulose fibrils connected by hemicellulose tethers embedded in a pectin gel providing mechanical strength for load-bearing.…”

“…For a normal metabolic function of plants, cells need to maintain high K + and low Na + levels. Thus, systematic exclusion of excess Na + ions from the cytoplasm or their accumulation within the vacuoles are the main adaptive mechanisms against ionic stress in plants [21]. This occurs through a highly sophisticated mechanism of ion homeostasis which involves the interplay of different molecular players.…”

“…Cl − ion signaling and transporters also regulate different pathways conferring abiotic stress tolerance in plants [50]. For instance, as an early salt stress response, the Cl − ion signal in the soil with elevated salt concentration has been connected to stomatal closure in an ABA dependent manner [21]. However, increased deposition of these ions during ionic stress is detrimental to plant growth and development [51].…”

“…It has been estimated that 1-2% of the O 2 consumed by plant tissues, leads to the ROS formation that mainly involves 1 O 2 , H 2 O 2 , O •− 2 , and OH• [83,84]. At this low concentration, ROS acts as a signaling molecule that triggers signal transduction pathways involved in growth and development [21,85]. However, in response to various abiotic stresses, the generation of increased levels of ROS causes irreversible damage to cells through their strong oxidative properties [86].…”