| Summary: | Understanding the molecular mechanisms in wheat response to nitrogen (N) fertilizer will help us to breed wheat varieties with improved yield and N use efficiency. Here, we cloned TaLAMP1-3A, -3B, and -3D, which were upregulated in roots and shoots of wheat by low N availability. In a hydroponic culture, lateral root length and N uptake were decreased in both overexpression and knockdown of TaLAMP1 at the seedling stage. In the field experiment with normal N supply, the grain yield of overexpression of TaLAMP1-3B is significantly reduced (14.5%), and the knockdown of TaLAMP1 was significantly reduced (15.5%). The grain number per spike of overexpression of TaLAMP1-3B was significantly increased (7.2%), but the spike number was significantly reduced (19.2%) compared with wild type (WT), although the grain number per spike of knockdown of TaLAMP1 was significantly decreased (15.3%), with no difference in the spike number compared with WT. Combined with the agronomic data from the field experiment of normal N and low N, both overexpression and knockdown of TaLAMP1 inhibited yield response to N fertilizer. Overexpressing TaLAMP1-3B greatly increased grain N concentration with no significant detrimental effect on grain yield under low N conditions; TaLAMP1-3 B is therefore valuable in engineering wheat for low input agriculture. These results suggested that TaLAMP1 is critical for wheat adaptation to N availability and in shaping plant architecture by regulating spike number per plant and grain number per spike. Optimizing TaLAMP1 expression may facilitate wheat breeding with improved yield, grain N concentration, and yield responses to N fertilizer.
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