Gene cloning and expression analysis of OvIF7GT in Onobrychis viciifolia

Isoflavones are a class of typical secondary metabolites in legumes. The diversity of their chemical structure aids plant growth and development and resistance to environmental stress. In the present study, a gene encoding isoflavone 7-O-glucosyltransferase (OvIF7GT) was cloned from the leaf of Onobrychis viciifolia with specific primers designed from the transcriptome data, and the gene was subjected to bioinformatics analysis, subcellular localization, and relative expression analysis under drought stress. The results revealed that the gene OvIF7GT had the sequence size of 1 512 bp and encodes a protein with 503 amino acids and molecular weight of 56 774.36 Da. The protein was proposed to be hydrophilic and had two transmembrane domains, 62 phosphorylation binding sites, and a theoretical isoelectric point of 5.51. Its conserved domain analysis showed that the protein OvIF7GT contained α-helix (41.75%) and random coils (35.79%); hence, it is proposed to be belonged to the isoflavone glucosyltransferase family. Its phylogenetic analysis showed that the protein OvIF7GT has the closest relationship with the Medicago truncatula and Cicer arietinum homologues. Subcellular localization analysis showed that OvIF7GT was mainly present in the cytoplasm and also distributed in the nucleus. The real-time fluorescence quantification (qRT-PCR) result revealed that the relative expression level of OvIF7GT gene was significantly induced by drought stress, the highest level was at 72 h under drought stress, and the expression level in the leaves was higher than that in roots. Therefore, the gene OvIF7GT probably plays a role in drought stress response and resistance of O. viciifolia.