Salt stress under the scalpel – dissecting the genetics of salt tolerance

Abstract

Summary Salt stress limits the productivity of crops grown under saline conditions, leading to substantial losses of yield in saline soils and under brackish and saline irrigation. Salt tolerant crops could alleviate these losses while both increasing irrigation opportunities and reducing agricultural demands on dwindling freshwater resources. However, despite significant efforts, progress towards this goal has been limited, largely because of the genetic complexity of salt tolerance for agronomically important yield‐related traits. Consequently, the focus is shifting to the study of traits that contribute to overall tolerance, thus breaking down salt tolerance into components that are more genetically tractable. Greater consideration of the plasticity of salt tolerance mechanisms throughout development and across environmental conditions furthers this dissection. The demand for more sophisticated and comprehensive methodologies is being met by parallel advances in high‐throughput phenotyping and sequencing technologies that are enabling the multivariate characterisation of vast germplasm resources. Alongside steady improvements in statistical genetics models, forward genetics approaches for elucidating salt tolerance mechanisms are gaining momentum. Subsequent quantitative trait locus and gene validation has also become more accessible, most recently through advanced techniques in molecular biology and genomic analysis, facilitating the translation of findings to the field. Besides fuelling the improvement of established crop species, this progress also facilitates the domestication of naturally salt tolerant orphan crops. Taken together, these advances herald a promising era of discovery for research into the genetics of salt tolerance in plants.

From genome to phenome: genome‐wide association studies and other approaches that bridge the genotype to phenotype gap

“…Morton et al . () discuss how advances in genomics and high‐throughput phenotyping are bridging the gap to gain insight into salt tolerance in plants. They consider how more sophisticated and comprehensive methodologies are required to dissect the complexity of this trait under different environments.…”

Key traits and genes associate with salinity tolerance independent from vigor in cultivated sunflower (Helianthus annuusL.)

“…Improving food security requires the development of crops that can withstand environmental stresses such as high salinity. Given the osmotic as well as ionic challenges presented by salt stress, the physiological and genetic basis of salinity tolerance is likely to be complex (Negrão et al, 2017; Morton et al, 2018). Here, we investigated the suites of traits underlying variation in salinity tolerance in sunflower, and examined their underlying genetic basis.…”

“…Accumulated Na poses a risk of ion toxicity (Munns and Tester, 2008) and must either be excreted (a trait limited to salt-adapted species; (Cheeseman, 2015)) or sequestered in roots and stems (Cuin et al, 2011; Munns et al, 2012; Guan et al, 2014) or vacuoles (Mansour et al, 2003; Hasegawa, 2013; Bassil et al, 2019; Shabala et al, 2019). An improved understanding of the genetic basis of the traits underlying salt tolerance would accelerate the development of increasingly resilient cultivars (Zhu et al, 2016; Morton et al, 2018). Given the large set of traits and mechanisms related to salinity tolerance (Munns and Tester, 2008; Munns et al, 2020a; Munns et al, 2020b), however, the ability to maintain productivity under saline conditions is likely to be genetically complex (Flowers, 2004; Munns, 2005).…”

“…Numerous metrics for stress tolerance exist, leading to potentially conflicting conclusions depending on which metric is employed (Zhu et al, 2016; Morton et al, 2018). For example, a high performing genotype under saline conditions (suggesting ‘tolerance’) could also experience a large percentage performance decrease in salt stress (suggesting ‘sensitivity’).…”

Systematic hormone-metabolite network provides insights of high salinity tolerance inPongamia pinnata(L.) pierre

“…To date, attempts are being made to extend the crop productivity on saline lands. However, progress of these attempts is greatly hampered by the genetic complexity of salt tolerance, which largely depends on physiological and genetic diversity of the plant and spatio-temporal heterogeneity of soil salinity (Morton et al, 2019). To address this issue, several plant species were introduced to rehabilitate the saline lands and certain economically important nitrogen fixing biofuel tree species are of immense importance not only for sustenance to saline marginal lands but also economic gain towards saline lands (Samuel et al, 2013; Hanin et al, 2016; Marriboina Attipalli, 2020a).…”