Improving crop salt tolerance using transgenic approaches: An update and physiological analysis

• Published in: Plant, cell and environment cell and environment, 2020-12, Vol.43 (12), p.2932-2956
• Main Authors: Kotula, Lukasz, Garcia Caparros, Pedro, Zörb, Christian, Colmer, Timothy D., Flowers, Timothy J.
• Format: Article
• Language: English
• Subjects: Agricultural production; Aquaporins; Climate change; Compartmentation; Crops; Environmental impact; Food production; Greenhouses; HKT1; Hydrogen; NHX; Physiology; plasma membrane ATPase; Proteins; Salinity; Salinity effects; Salinity tolerance; Salinization; Salt; Salt tolerance; salt ‘exclusion’; Shoots; sodium vacuolar compartmentation; SOS1; Species; Transgenic plants; vacuolar‐H+ATPase; vacuolar‐H+PPase; Vacuoles; Water deficit
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/pce.13865

Salinization of land is likely to increase due to climate change with impact on agricultural production. Since most species used as crops are sensitive to salinity, improvement of salt tolerance is needed to maintain global food production. This review summarises successes and failures of transgenic approaches in improving salt tolerance in crop species. A conceptual model of coordinated physiological mechanisms in roots and shoots required for salt tolerance is presented. Transgenic plants overexpressing genes of key proteins contributing to Na+ ‘exclusion’ (PM‐ATPases with SOS1 antiporter, and HKT1 transporter) and Na+ compartmentation in vacuoles (V‐H+ATPase and V‐H+PPase with NHX antiporter), as well as two proteins potentially involved in alleviating water deficit during salt stress (aquaporins and dehydrins), were evaluated. Of the 51 transformations, with gene(s) involved in Na+ ‘exclusion’ or Na+ vacuolar compartmentation that contained quantitative data on growth and include a non‐saline control, 48 showed improvements in salt tolerance (less impact on plant mass) of transgenic plants, but with only two tested in field conditions. Of these 51 transformations, 26 involved crop species. Tissue ion concentrations were altered, but not always in the same way. Although glasshouse data are promising, field studies are required to assess crop salinity tolerance. Since most crops are salt sensitive, salinization of land threatens our agricultural production. In this review, we summarise the successes and failures in generating salt‐tolerant crops through the up‐regulation of specific genes and/or the transfer of one or more genes between species, with focus on key genes involved in regulation of net uptake and vacuolar compartmentation of Na+.