Physiological and biochemical adaptive strategies in citrus plants facing cold stress
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.
