Making wheat salt tolerant:What is missing?

The growing global population presents a significant challenge to ensuring food security,further compounded by the increasing threat of salinity to agricultural productivity.Wheat,a major staple food providing 20%of the total caloric intake for humans,is susceptible to salinity stress.Developing new salttolerant wheat cultivars using wheat breeding techniques and genetic modifications is crucial to addressing this issue while ensuring the sustainability and efficiency of wheat production systems within the prevailing climate trend.This review overviews the current landscape in this field and explores key mechanisms and associated genetic traits that warrant attention within breeding programs.We contend that traditional approaches to breeding wheat for Na^(+)exclusion have limited applicability across varying soil salinity levels,rendering them inefficient.Moreover,we question current phenotyping approaches,advocating for a shift from whole-plant assessments to cell-based phenotyping platforms.Finally,we propose a broader use of wild wheat relatives and various breeding strategies to tap into their germplasm pool for inclusion in wheat breeding programs.

K^+ retention in leaf mesophyll, an overlooked component of salinity tolerance mechanism:A case study for barley

Plant salinity tolerance is a physiologically complex trait, with numerous mechanisms contributing to it. In this work, we show that the ability of leaf mesophyll to retain K＋ represents an important and essentially overlooked component of a salinity tolerance mechanism. The strong positive correlation between mesophyll K＋ retention ability under saline conditions （quantified by the magnitude of NaCl-induced K＋ efflux from mesophyll） and the overall salinity tolerance （relative fresh weight and/or survival or damage under salinity stress） was found while screening 46 barley （Hordeum vulgare L.） genotypes contrasting in their salinity tolerance. Genotypes with intrinsically higher leaf K＋ content under control conditions were found to possess better K＋ retention ability under salinity and, hence, overall higher tolerance. Contrary to previous reports for barley roots, K＋ retention in mesophyll was not associated with an increased H＋-pumping in tolerant varieties but instead correlated negatively with this trait. These findings are explained by the fact that increased H＋ extrusion may be needed to charge balance the activity and provide the driving force for the high affinity HAK/KUP K＋ transporters required to restore cytosolic K＋ homeostasis in salt-sensitive genotypes.

Rewilding staple crops for the lost halophytism:Toward sustainability and profitability of agricultural production systems

Abiotic stress tolerance has been weakened during the domestication of all major staple crops.Soil salinity is a major environmental constraint that impacts over half of the world population;however,given the increasing reliance on irrigation and the lack of available freshwater,agriculture in the 21st century will increasingly become saline.Therefore,global food security is critically dependent on the ability of plant breeders to create high-yielding staple crop varieties that will incorporate salinity tolerance traits and ac-count for future climate scenarios.Previously,we have argued that the current agricultural practices and reliance on crops that exclude salt from uptake is counterproductive and environmentally unsustainable,and thus called for a need for a major shift in a breeding paradigm to incorporate some halophytic traits that were present in wild relatives but were lost in modern crops during domestication.In this review,we provide a comprehensive physiological and molecular analysis of the key traits conferring crop halophy-tism,such as vacuolar Na+sequestration,ROS desensitization,succulence,metabolic photosynthetic switch,and salt deposition in trichomes,and discuss the strategies for incorporating them into elite germ-plasm,to address a pressing issue of boosting plant salinity tolerance.