Genome–Wide Identification of the GRAS Family Genes in Melilotus albus and Expression Analysis under Various Tissues and Abiotic Stresses

Abstract

The GRAS gene family is a plant-specific family of transcription factors, which play an important role in many metabolic pathways, such as plant growth and development and stress response. However, there is no report on the comprehensive study of the GRAS gene family of <i>Melilotus albus</i>. Here, we identified 55 <i>MaGRAS</i> genes, which were classified into 8 subfamilies by phylogenetic analysis, and unevenly distributed on 8 chromosomes. The structural analysis indicated that 87% of <i>MaGRAS</i> genes have no intron, which is highly conservative in different species. MaGRAS proteins of the same subfamily have similar protein motifs, which are the source of functional differences of different genomes. Transcriptome and qRT-PCR data were combined to determine the expression of 12 <i>MaGRAS</i> genes in 6 tissues, including flower, seed, leaf, stem, root and nodule, which indicated the possible roles in plant growth and development. Five and seven <i>MaGRAS</i> genes were upregulated under ABA, drought, and salt stress treatments in the roots and shoots, respectively, indicating that they play vital roles in the response to ABA and abiotic stresses in <i>M. albus</i>. Furthermore, in yeast heterologous expression, <i>MaGRAS12</i>, <i>MaGRAS34</i> and <i>MaGRAS33</i> can enhance the drought or salt tolerance of yeast cells. Taken together, these results provide basic information for understanding the underlying molecular mechanisms of GRAS proteins and valuable information for further studies on the growth, development and stress responses of GRAS proteins in <i>M. albus</i>.