Expressional characterization of galacturonosyltransferase-like gene family in Eucalyptus grandis implies a role in abiotic stress responses

Glycosyltransferase (GT) plays a pivotal role in cell wall biosynthesis in plants. Galacturonosyltransferase-like (GATL) genes, belonging to the GT8 family, have been proven to be involved in pectin and/or xylan biosynthesis of the cell wall. Here, we identified eight GATL genes from the Eucalyptus grandis genome and characterized the gene structure and chromosomal location. The genes were found to be distributed across five chromosomes, including two pairs in block duplication regions. None of the EgrGATL genes contained introns. And, with the exception of EgrGATL8, the remainder of the EgrGATL proteins possessed the three classic motifs characteristic of all GATL proteins. Expression analysis in the different tissues showed that EgrGATL1, EgrGATL4, and EgrGATL8 were highly expressed in xylem and phloem; EgrGATL6 exhibited the highest expression in leaves, and in phloem and leaves, EgrGATL2 and EgrGATL3 both exhibited very low expression. However, the abiotic stress response of plants can be affected by changes in the components and structure of the cell wall. The expression patterns of EgrGALTs under low-temperature, high-temperature, drought, salinity, and abscisic acid (ABA) treatments were assessed by qRT-PCR. The results showed that most of the EgrGATL genes could be induced under low temperature, and some were even able to increase their expression level under high temperature. Under drought conditions, the expression levels of most of the genes initially increased and then decreased. Similar expression patterns were observed in leaves under treatment with NaCl and ABA. Our results provide fundamental information towards the functional dissection of EgrGATL genes and their potential involvement in improving plant abiotic stress tolerance.