K Deprivation Modulates the Primary Metabolites and Increases Putrescine Concentration in Brassica napus

Potassium (K) plays a crucial role in plant growth and development and is involved in different physiological and biochemical functions in plants. needs higher amount of nutrients like nitrogen (N), K, phosphorus (P), sulfur (S), and boron (B) than cereal crops. Previous studies in are mainly focused on the role of N and S or combined deficiencies. Hence, little is known about the response of to K deficiency. Here, a physiological, biochemical, and molecular analysis led us to investigate the response of hydroponically grown plants to K deficiency. The results showed that was highly sensitive to the lack of K. The lower uptake and translocation of K induced expression and significantly declined the growth of after 14 days of K starvation. The lower availability of K was associated with a decrease in the concentration of both S and N and modulated the genes involved in their uptake and transport. In addition, the lack of K induced an increase in Ca and Mg concentration which led partially to the accumulation of positive charge. Moreover, a decrease in the level of arginine as a positively charged amino acid was observed which was correlated with a substantial increase in the polyamine, putrescine (Put). Furthermore, K deficiency induced the expression of as a key gene in abscisic acid (ABA) biosynthetic pathway which was associated with an increase in the levels of ABA. Our findings provided a better understanding of the response of to K starvation and will be useful for considering the importance of K nutrition in this crop.