The Role of Chitosan in Improving the Cold Stress Tolerance in Strawberry varieties

Cold stress is considered one of the main factors that influence strawberry production in an open field.This study aimed to estimate the effects of three different concentrations of chitosan (COS) solution used by foliar spraying on the vegetative growth and yield parameters of three strawberry varieties.Moreover, the impact of foliar spraying of COS solutions on the induction of biochemical changes linked to cold stress was assessed.In this study, three different concentrations of COS solution (250, 500, and 1000 ppm) were applied to three strawberry varieties that genetically different by foliar spraying, compared with the untreated control (0 ppm COS).The results showed that the COS solution led to significant and nonsignificant increases in the vegetative and fruit growth parameters, depending on the concentration of COS and strawberry variety.On the other hand, it was shown that foliar application of strawberry varieties with COS solution under chilling stress causes changes in gene expression in strawberry varieties, either up-regulated or down-regulated.Furthermore, novel proteins related to cold tolerance, including pathogen-related proteins (PRPs), were identified in three strawberry varieties.For instance, new polypeptides of MWs (53 and 44 kDa) and (53; 44; and 8 kDa) were scored in Fortuna variety that was sprayed with 250 and 500 ppm COS respectively, compared with the corresponding control.In addition, one subunit of 29 kDa was detected in Florid and Festival varieties treated with 500 and 1000 ppm COS solutions.Consequently, these proteins could be used as biomarkers related to cold tolerance.Therefore, foliar spraying of COS can be used in strawberry breeding programs to protect them from cold stress.