Climate-resilient crops: lessons from xerophytes

Developing climate-resilient crops is critical for future food security and sustainable agriculture under cur-rent climate scenarios. Of specific importance are drought and soil salinity. Tolerance traits to these stressesare highly complex, and the progress in improving crop tolerance is too slow to cope with the growingdemand in food production unless a major paradigm shift in crop breeding occurs. In this work, we com-bined bioinformatics and physiological approaches to compare some of the key traits that may differentiatebetween xerophytes (naturally drought-tolerant plants) and mesophytes (to which the majority of the cropsbelong). We show that both xerophytes and salt-tolerant mesophytes have a much larger number of copiesin key gene families conferring some of the key traits related to plant osmotic adjustment, abscisic acid(ABA) sensing and signalling, and stomata development. We show that drought and salt-tolerant specieshave (i) higher reliance on Na for osmotic adjustment via more diversified and efficient operation of Na+/H+tonoplast exchangers (NHXs) and vacuolar H+- pyrophosphatase (VPPases); (ii) fewer and faster stomata;(iii) intrinsically lower ABA content; (iv) altered structure of pyrabactin resistance/pyrabactin resistance-like(PYR/PYL) ABA receptors; and (v) higher number of gene copies for protein phosphatase 2C (PP2C) andsucrose non-fermenting 1 (SNF1)-related protein kinase 2/open stomata 1 (SnRK2/OST1) ABA signallingcomponents. We also show that the past trends in crop breeding for Na+exclusion to improve salinitystress tolerance are counterproductive and compromise their drought tolerance. Incorporating these geneticinsights into breeding practices could pave the way for more drought-tolerant and salt-resistant crops,securing agricultural yields in an era of climate unpredictability.