Stress Resistance And Functional Identification Of A Transcription Factor Gene SiNF-YA6 From Millet

Nitrogen is one of the most important nutrients in plant growth and development. The nitrogen uptake efficiency is an important factor that affects yield.Therefore, uncovering the regulatory mechanisms of plant response to low nitrogen stress has a great important significance for cultivating crops of nitrogen efficient varieties.Nuclear transcription factor Y(NF-Y) belongs to a transcription factor gene family widely existing in eukaryotic. NF-Y-like transcription factors are involved in the process of gene expression regulation of plant growth and development and stress responses. So far, it is never been reported that NF-Y-like transcription factors are involved in plant resistance to low nitrogen stress.In this study, a NF-Y-like transcription factor gene SiNF-YA6 was isolated from millet, and its characteristics and biological function were identified. The major findings are as follows:1. SiNF-YA6 is length of 714 bp encoding 237 amino acids. SiNF-YA6 contains a CBF conservative domain with 62 amino acids. Phylogenetic tree analysis showed that NF-YA was fell into 6 classes, and SiNF-YA6 belongs to the fifth class. SiNF-YA6 was the highest homology with a rice NF-YA protein(Os03g07880)(77.4%).2. SiNF-YA6 mainly expressed in millet roots. NF-YA6 was induced by low nitrogen stress, and its expression reach peak after the treatment of the 5 d that raised about 5 times comparing with expression level in beginning of treatment. While transcription of SiNF-YA6 under high salt, drought, ABA treatment also showed a trend of increasing.3. Subcellular localization indicated that SiNF-YA6 mainly located on the plasmalemma and nucleus in plant cell.4. Results of low nitrogen stress resistance test showed that main root length and root surface area of SiNF-YA6 transgenic Arabidopsis were significantly higher than in wild type Arabidopsis, and fresh weight of transgenic plants was also significantly greater than wild type plants(p<0.01) under low nitrogen stress(total nitrogen content of 1 mmol·L-1), and growth of SiNF-YA6 transgenic Arabidopsis had no obvious difference with wild-type Arabidopsis under SA and GA treatments. Those results indicated that overexpression of SiNF-YA6 gene significantly enhanced transgenic plants resistance to low nitrogen stress. Some nitrogen transporter genes were up-regulated in SiNF-YA6 transgenic Arabidopsis.Overexpression of SiNF-YA6 enhanced transgenic plants tolerance to low nitrogen stress by up-regulated expression of several nitrogen transporter genes, which will give new candidate for improvement of the nitrogen use efficiency in crops.