Climate change has increased extreme weather events frequency and intensity. Although the incidence of high temperatures has been studied on several plant species, the study of low temperatures has been relegated to the background, whereas crops as citrus could be particularly sensitive to chilling due to their origins in tropical and subtropical areas. In this work, plants of two citrus genotypes, Carrizo citrange (CC) and Cleopatra mandarin (CM), were subjected to cold stress at 10/4ºC (day/night) temperature, maintaining control plants at 25/18 ºC, with a 16 h photoperiod. Leaf tissue was sampled after 3 and 7 days for further analyses. The results exhibited a similar photosynthetic response in both genotypes, decreasing of gas exchange parameters. The study of different osmoprotectants revealed a major role of proline and soluble sugars in the osmotic response of citrus to chilling.
Notably, CC exhibited a greater capacity to increase proline content, while CM maintained higher basal levels of this compound. Phytohormone analysis denoted the importance of abscisic acid (ABA) compared to other plant hormones. CC plants had a higher capacity to modulate ABA content than CM ones, which could lead to a higher tolerance, reflected by the lower chlorophyll degradation and lower oxidative stress (marked as malondialdehyde content) of CC compared to CM. These results suggest that, although both genotypes exhibit a moderate tolerance to chilling, they may have different adaptive strategies to this stress. Furthermore, this study delves into the physiological, biochemical and molecular strategies employed by citrus plants to cope with low temperatures.
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Vicente Vives-Peris, Joan Vicente-Valls, Lledó Rodríguez-Azorín, Aurelio Gómez-Cadenas & María F. López-Climent
Plant Growth Regulation (2025) 105:1575–1590
https://doi.org/10.1007/s10725-025-01361-z
Springer Nature Link
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