Genome-wide identification and expression analysis of family genes in Chinese hickory ( Sarg.) Under various abiotic stresses and grafting.

Auxin is essential for regulating plant growth and development as well as the response of plants to abiotic stresses. AUX/LAX proteins are auxin influx transporters belonging to the amino acid permease family of proton-driven transporters, and are involved in the transport of indole-3-acetic acid (IAA). However, how genes respond to abiotic stresses in Chinese hickory is less studied. For the first time identification, structural characteristics as well as gene expression analysis of the gene family in Chinese hickory were conducted by using techniques of gene cloning and real-time fluorescent quantitative PCR. Eight were identified in Chinese hickory, all of which had the conserved structural characteristics of . CcAUX/LAXs were most closely related to their homologous proteins in , which was in consistence with their common taxonomic character of woody trees. exhibited different expression profiles in different tissues, indicating their varying roles during growth and development. A number of light-, hormone-, and abiotic stress responsive -acting regulatory elements were detected on the promoters of genes. genes responded differently to drought and salt stress treatments to varying degrees. Furthermore, genes exhibited complex expression changes during Chinese hickory grafting. These findings not only provide a valuable resource for further functional validation of , but also contribute to a better understanding of their potential regulatory functions during grafting and abiotic stress treatments in Chinese hickory.