Genome-wide identification and expression analysis of LBD gene family in soybean

Transcription factor plays an important role in plant growth and development. TheLBD(lateral organ boundaries domain) gene family is a group of plant-specific transcription factors that play key roles in the regulation of plant growth, nutrient metabolism, and response to adversity stress. In this study, the soybeanLBDgene family was systematically identified and analyzed for expression patterns at the genomic and transcriptomic levels using bioinformatics methods. The phylogenetic results show that the 89 members of the soybeanLBDgene family are classified into 2 major classes and 7 subfamilies. The analysis of physicochemicalproperties shows that the amino acid numbers encoded by the soybeanLBDgene family range from 50 aa to 325 aa, the molecular weights range from 8 164.16 Da to 60 499.65 Da, the isoelectric points range from 4.69 pl to 9.15 pl, and the coefficients of instabilityrange from 43.46 to 83.94. Motifs and gene structure analysis reveal that theLBDgene family members are highly conserved. Promoter cis-acting element analysis shows that theLBDgene family members contain 29 cis-acting elements related to plant light response, 11 elements related to phytohormones, and 6 elements related to abiotic and biotic stress response. Transcriptome analysis reveals that the soybeanLBDgenes are differentially expressed in the elongation zone (EZ), mature zone (MZ), and stem tip (ST) of the growing internodes of DN50. LBD family members are highly expressed mainly in MZ and ST, among which GmLBD5, GmLBD23, GmLBD38, GmLBD46, GmLBD49, GmLBD71, GmLBD75, and GmLBD78 are highly expressed in EZ, MZ, and ST, which are the key candidate genes to regulate the height of soybean plants. Some genes are found to have expression specificity in stem tissues, for example, GmLBD83 is highly expressed in the EZ, whereas GmLBD15, GmLBD59, GmLBD61, and GmLBD84are only highly expressed in the MZ, and GmLBD14, GmLBD18, GmLBD21, GmLBD27, GmLBD55, GmLBD66, and GmLBD70are only highly expressed in ST. The results of this study provide candidate genes for in-depth analysis of the molecular mechanism of LBD genes in regulating the growth and development of soybean internodes.