Opportunities for Developing Salt‐tolerant Wheat and Barley Varieties

Abstract

Salinity is a major constraint limiting crop yields around the world. While considerable research to understand and enhance the salinity tolerance of plants has occurred, few commercially available salt‐tolerant bread wheat ( Triticum aestivum ), durum wheat ( Triticum durum ), or barley ( Hordeum vulgare ) varieties have been developed for farmers. This lack of salt‐tolerant varieties is despite all publications highlighting issues around global food security, the need to increase crop production to feed an increasing human population, the effects of more variable climate and farmland being degraded by abiotic stresses. We explore the progress to date in using forward and reverse genetic approaches to identify loci and candidate genes linked to plant salinity‐tolerance sub‐traits, and why, despite substantial research in understanding salt tolerance mechanisms, very few genes or loci have been introduced into commercially available varieties. We propose the need for a greater focus on validating glasshouse‐based findings of salt tolerance in saline fields, the fine mapping of quantitative trait loci linked to salt‐tolerance sub‐traits to underlying genes, and the use of marker‐assisted selection and speed breeding to pyramid beneficial salinity‐tolerance sub‐traits to develop high‐yielding bread wheat, durum wheat, and barley varieties.

Identification of salt tolerance QTL in a wheat RIL mapping population using destructive and non-destructive phenotyping

“…To date, a limited number of studies have been conducted to identify QTL linked with shoot ion-independent tolerance and/ or Claccumulation in bread wheat, with the majority of studies focusing on the identification of QTL for shoot ion accumulation (mostly Na + exclusion and K + accumulation) (Dubcovsky et al 1996;Ma et al 2007;Genc et al 2010Genc et al , 2013Díaz De León et al 2011;Oyiga et al 2018;Asif et al 2019). Shoot ion-independent tolerance is an important tolerance mechanism and helps plants in maintaining tissue expansion and tillering during the initial phase of salt stress before salt accumulates to toxic levels in the shoot (Roy et al 2014).…”

“…QTL mapping is a valuable tool for studying complex polygenic traits like salinity tolerance in various crops (Ortiz 1998;Ruttan 1999;Roy et al 2011). QTL for salinity tolerance have been identified in a large number of plant species including bread wheat (Asif et al 2019); however, limited success has been made so far regarding the identification of candidate genes and development of new salt tolerant wheat cultivars (Gilliham et al 2017;Asif et al 2019). Hence, more studies are needed to identify and understand salt tolerance mechanisms and the underlying genes responsible for such traits.…”

Identifying the genetic control of salinity tolerance in the bread wheat landrace Mocho de Espiga Branca

“…Although genes that encode Cl − channels or transporters have been identified (see Colmenero-Flores et al 2007;Barbier-Brygoo et al 2011;De Angeli et al 2013Henderson et al 2014Herdean et al 2016;Li et al 2016Li et al , 2017Geilfus 2018Geilfus , 2019Wu and Li 2019 for examples), the genes/proteins specifically involved in Cl − salinity tolerance in cereals remain unknown. To date, few studies have reported QTL for plant Cl − accumulation in bread wheat under salinity (Asif et al 2019).…”

An approach to detecting quantitative trait loci and candidate genes associated with salinity tolerance in faba bean (Vicia faba)

“…Most of the previous studies on salinity tolerance in crops have focused on the role of Na + and K + and ignored Cl − (Asif et al., 2019). Although saline soils contain both Na + and Cl − ions, not much is known about physiological and genetic control tolerance mechanisms related to Cl − toxicity compared with Na + toxicity (Genc et al., 2014; Teakle & Tyerman, 2010).…”