Two Splicing Variants of OsNPF7.7 Regulate Shoot Branching and Nitrogen Utilization Efficiency in Rice

Rice includes 93 nitrate and peptide transporters family (NPF) members that facilitate the soil uptake and internal reallocation of nitrogen for growth and development. This study demonstrated that had two splicing variants, and altered expression of each variant could regulate shoot branching and nitrogen utilization efficiency (NUtE) in rice. The expression of both variants was down-regulated in the buds by increased nitrogen level in the rice variety ZH11. The expression level of long-variant was higher in panicles at reproductive stage, however, the expression level of short-variant was higher in buds and leaves at vegetative stage compared to each other in ZH11. OsNPF7.7-1 was localized in the plasma membrane, whereas OsNPF7.7-2 was localized in the vacuole membrane. Furthermore, the results indicated that the expression level of each variant for determined axillary bud outgrowth, and then influenced the rice tiller number. Overexpression of could promote nitrate influx and concentration in root, whereas overexpression of could improve ammonium influx and concentration in root. RNAi and lines of showed an increased amount of amino acids in leaf sheaths, but a decreased amount in leaf blades, which affected nitrogen allocation and plant growth. The elevated expression of each variant for in ZH11 enhanced NUtE using certain fertilization regimes under paddy field conditions. Moreover, overexpression of each variant for in KY131 increased significantly the filled grain number per plant. Thus, increased each variant of has the potential to improve grain yield and NUtE in rice.