Effect of Seedling Nitrogen Condition on Subsequent Vegetative Growth Stages and Its Relationship to the Expression of Nitrogen Transporter Genes in Rice.

Nitrogen (N) deficiency is one of the most common problems in soils, limiting crop growth and production. However, the effects of N limitation in seedlings on vegetative growth remain poorly understood. Here, we show that N limitation in rice seedlings restricted vegetative growth but not yield. Aboveground parts were affected mainly during the period of tillering, but belowground parts were sensitive throughout vegetative growth, especially during panicle development. At the tillering stage, N-limited plants had a significantly lower N content in shoots, but not in roots. On the other hand, N content in roots during the panicle development stage was significantly lower in N-limited plants. This distinct response was driven by significant changes in expression of N transporter genes during growth. Under N limitation, N translocation from roots to shoots was greatly sped up by systemic expression of N transporter genes to obtain balanced growth. N limitation during the seedling stage did not reduce any yield components. We conclude that the N condition during the seedling stage affects physiological responses such as N translocation through the expression of N transporter genes.