Abstract:

In order to clarify the similarities, differences and biological functions of Nodule inception(NIN)genes, which expressed core transcription factors NIN involved in all the biological processes from rhizobia infection to root nodule formation and nitrogen fixation in soybean, and integrates nodulation and autoregulation of nodulation signals to dynamically control the number of nodules, methods of bioinformatics were used to analyse the phylogeny, protein sequence, gene sequence and promoter elements of the four GmNINs, and Real-time PCR were carried out to verify the tissue expression pattern.The results showed that the four GmNINs proteins with similar protein sequences belonged to the specific NIN protein family in Legumes, located in the nucleus, had multiple phosphorylation sites and similar core tertiary structure with significant difference in corner. Acorrdingly, the above results indicate that the four GmNINs proteins may be redundant in core functions, but have differences in specific expression patterns.Analysis of the upstream-3 kb promoter sequence of GmNINs showed that the promoter sequence of GmNINs contained many elements such as ABRE, DRE1 and other elements related to stress and hormone response, except NBS and CYC elements.Transcriptome analysis and Real-time PCR results showed that GmNINs were highly expressed in nodules and inhibited in high nitrogen condition; they responded to salt and drought stress of varying degrees, among which GmNIN2a and GmNIN2b were more sensitive and significant in responding to abiotic stress, and GmNIN2a and GmNIN2b may play an important role in the process of plant response to abiotic stress. In short, the results revealed that GmNINs not only regulate the nodule number of soybean and nodulation, but also participate in the process of root response to abiotic stress. The discovery of this regulatory mechanism provides essential clues for breeding new varieties with high quality and high yield.

Key words: Soybean, NIN transcription factor, Bioinformatics, Abiotic stress, Expression analysis