Genomics, Physiology, and Molecular Breeding Approaches for Improving Salt Tolerance

Abstract

Salt stress reduces land and water productivity and contributes to poverty and food insecurity. Increased salinization caused by human practices and climate change is progressively reducing agriculture productivity despite escalating calls for more food. Plant responses to salt stress are well understood, involving numerous critical processes that are each controlled by multiple genes. Knowledge of the critical mechanisms controlling salt uptake and exclusion from functioning tissues, signaling of salt stress, and the arsenal of protective metabolites is advancing. However, little progress has been made in developing salt-tolerant varieties of crop species using standard (but slow) breeding approaches. The genetic diversity available within cultivated crops and their wild relatives provides rich sources for trait and gene discovery that has yet to be sufficiently utilized. Transforming this knowledge into modern approaches using genomics and molecular tools for precision breeding will accelerate the development of tolerant cultivars and help sustain food production.

Salinity and crop yield

“…). Ismail & Horie () that summarizes progress in breeding approaches for improving salt tolerance in rice, wheat and barley refer the reader to the recent review.…”

“…However, what is needed are screening approaches that estimate performance during both the vegetative phase and the reproductive stage, as it was done for the salt tolerant rice variety BRRI Dhan 10 (Islam et al 2008). Ismail & Horie (2017) that summarizes progress in breeding approaches for improving salt tolerance in rice, wheat and barley refer the reader to the recent review.…”

“…Flooding-induced hypoxia and salinity can occur as combined stress. Breeding efforts for salt-tolerant rice demonstrate that it is worthwhile to introduce salt tolerance landraces that are traditionally used by local farmers in coastal saline areas into breeding programs, as they enrich the genetic diversity of our modern high yield crops with novel genes and alleles for salt tolerance (Ismail & Horie 2017). The use of halophytes as valuable cash crops or the development of crops from halophytes might be an additional option (Flowers & Muscolo 2015).…”

Identification of new QTL for salt tolerance from rice variety Pokkali

“…Salt‐stress response of plant is regulated by various biological processes, such as ion homeostasis and compartmentalization, osmotic adjustment, stomatal movement and ROS scavenging (Deinlein et al, ; Gupta & Huang, ; Hasegawa, ; Horie, Karahara, & Katsuhara, ; Zhu, ). It is generally accepted that most glycophytes maintain low Na + , high K + and high K + /Na + ratio in shoots under salt stress, implying that Na + exclusion is crucial for the survival of these plants in salt‐affected environments (Deinlein et al, ; Horie et al, ; Ismail & Horie, ; Keisham, Mukherjee, & Bhatla, ; Kumar et al, ; Shabala & Cuin, ; Zhu, ). Plant plasma membrane transporters for Na + and K + play an essential role in tolerance to salinity stress (Schroeder et al, ).…”

“…Moreover, soil salinization caused by human activity and climate change is progressively increasing (Takagi et al, 2015). Salt stress imposes both osmotic stress and ion toxicity, which consequently reduces crop productivity and grain yield (Ismail & Horie, 2017;Kumar, Kumar, Kim, Ryu, & Cho, 2013). Rice (Oryza sativa L.), which feeds over half of the world's population, is the most salt-sensitive species among all cereals (Munns & Tester, 2008).…”