Co-overexpression of AtCBL9, AtCIPK23 and AtAKT1 enhances K + uptake of sugarcane under low-K + stress

Low potassium (K + ) availability is a major constraint to sugarcane growth and production. Previous studies have identified a calcium-signaling pathway that includes two calcineurin B-like calcium sensors (CBL1/CBL9) and a target interacting protein kinase (CIPK23) that activates the inward shaker-like potassium channel (AKT1), responsible for K + uptake in plant roots. In this study, three components of the signaling pathway, AtCBL9, AtCIPK23 and AtAKT1 from Arabidopsis thaliana were co-overexpressed in sugarcane (Saccharum spp.) through particle bombardment. The results showed about 31% and 35% increase of K + content in transgenic plants in low-K + stress assay of tissue culture and hydroponic culture, respectively, compared to non-transgenic line. Under low K + supply condition, transgenic lines have longer roots, higher plant height, heavier dry weight than non-transgenic line, indicating the transgenic lines grow better than non-transgenic lines. This study indicated that co-overexpression of AtCBL9, AtCIPK23 and AtAKT1 could significantly increase sugarcane K + uptake ability and tolerance to low-K + stress. These findings would have significant implications for improving stress tolerance of sugarcane in areas where K + supply is low.