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The response of five Lycopersicon species to 14 days moderate chilling at 10°C under low light (75 μmol m−2 s−1) and subsequent recovery was examined by measurements on relative shoot growth rate, leaf dry matter and carbohydrate content, CO2‐exchange and pigment composition. In addition, the susceptibility to dark chilling and temperature dependence of chloroplast electron transport were analyzed by Chl a fluorescence measurements. During 7 days of recovery at 25/20°C subsequent to chilling, the domestic tomato Lycopersiconesculentum (L.) Mill. cv. Abunda exhibited a small capacity for shoot regrowth (39%) compared to the low‐altitude wild species L. pimpinellifolium (Jusl.) Mill. PI187002 (82%) and three wild species originating from high altitude: L. peruvianum Mill. LA 385 (92%), L. hirsutum Humb. & Bonpl. LA 1777 (67%) and L. chilense Dunn. LA 1970 (71%). The inter‐specific differences in chilling sensitivity at the chloroplast level, analyzed by the decline of the maximum rate of induced Chl fluorescence rise (FR) after 40 h at 0°C and the temperature at which qP reached the value 0.5, correlated in general well with the measured differences at whole plant level, measured by the post‐chilling regrowth capacity. Chilling resulted in a larger increase in leaf dry matter content in L. esculentum (45%) and L. pimpinellifolium (37%) compared to the high‐altitude species (13–16%), which could be attributed to a stronger accumulation of both soluble sugars and starch in mature leaves of the domestic and low‐altitude species. Photosynthetic and dark respiration rates during chilling could not account for this difference. The recovery of photosynthesis was better in the high‐altitude species. Chl content per unit leaf area decreased more throughout the experiment in the domestic and low‐altitude species (63–73%) than in their relatives from high altitude (8–29%). In response to chilling, the domestic and low‐altitude species showed an increase in the total xanthophyll cycle pool on Chl basis, whereas the de‐epoxidation state of the xanthophyll cycle increased in the high‐altitude wild species. Both responses resulted in increased zeaxanthin levels in chilled leaves of all Lycopersicon species. [ABSTRACT FROM AUTHOR]

Background: With soil salinity levels rising at an alarming rate, accelerated by climate change and human interventions, there is a growing need for crop varieties that can grow on saline soils. Alfalfa (Medicago sativa) is a cool-season perennial leguminous crop, commonly grown as forage, biofuel feedstock, and soil conditioner. It demonstrates significant potential for agricultural circularity and sustainability, for example by fixing nitrogen, sequestering carbon, and improving soil structures. Although alfalfa is traditionally regarded as moderately salt-tolerant species, modern alfalfa varieties display specific salt-tolerance mechanisms, which could be used to pave alfalfa's role as a leading crop able to grow on saline soils., Scope: Alfalfa's salt tolerance underlies a large variety of cascading biochemical and physiological mechanisms. These are partly enabled by alfalfa's complex genome structure and out-crossing nature, which on the other hand entail impediments for molecular and genetic studies. This review first summarizes the general effects of salinity on plants and the broad-ranging mechanisms for dealing with salt-induced osmotic stress, ion toxicity, and secondary stress. Secondly, we address defensive and adaptive strategies that have been described for alfalfa, such as the plasticity of alfalfa's root system, hormonal crosstalk for maintaining ion homeostasis, spatiotemporal specialized metabolite profiles, and the protection of alfalfa-rhizobia associations. Finally, bottlenecks for research of the physiological and molecular salt-stress responses as well as biotechnology-driven improvements of salt tolerance are identified and discussed., Conclusion: Understanding morpho-anatomical, physiological, and molecular responses to salinity is essential for the improvement of alfalfa and other crops in saline land reclamation. This review identifies potential breeding targets for enhancing alfalfa performance stability and general crop robustness for rising salt levels as well as to promote alfalfa applications in saline land management., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Annals of Botany Company.)