Abstract
Potassium, an essential inorganic cation, is crucial for the growth of oil crops like Brassica napus L. Given the scarcity of potassium in soil, enhancing rapeseed's potassium utilization efficiency is of significant importance. This study identified 376 potassium utilization genes in the genome of B. napus ZS11 through homologous retrieval, encompassing 7 functional and 12 regulatory gene families. These genes are unevenly distributed across 19 chromosomes, and the proteins encoded by these genes are mainly localized in the cell membrane, vacuoles, and nucleus. Microsynteny analysis highlighted the role of small-scale replication events and allopolyploidization in the expansion of potassium utilization genes, identifying 77 distinct types of cis-acting elements within their promoter regions. The regulatory mechanisms of potassium utilization genes were provided by analyses of transcription factors, miRNA, and protein interaction networks. Under low potassium stress, the potassium utilization genes, particularly those belonging to the KUP and CBL families, demonstrate pronounced co-expression. RNA-seq and RT-qPCR analysis identified the BnaZSHAK5.2 gene, which is a high-affinity potassium ion transporter, playing a crucial role in the stress response to potassium deficiency in B. napus, as its expression is strongly induced by low potassium stress. A functional complementation study demonstrates that the BnaZSHAK5.2 gene could rescue the primary root growth of the Athak5 mutant under low potassium conditions, confirming its role in response to low potassium stress by sustaining root development.