Isolation of developing secondary xylem specific cellulose synthase genes and their expression profiles during hormone signalling in Eucalyptus tereticornis

Abstract

Cellulose synthases (CesA) represent a group of β-1, 4 glycosyl transferases involved in cellulose biosynthesis. Recent reports in higher plants have revealed that two groups of CesA gene families exist, which are associated with either primary or secondary cell wall deposition. The present study aimed at identifying developing secondary xylem specific cellulose synthase genes from Eucalyptus tereticornis, a species predominantly used in paper and pulp industries in the tropics. The differential expression analysis of the three EtCesA genes using qRT-PCR revealed 49 to 87 fold relative expression in developing secondary xylem tissues. Three full length gene sequences of EtCesA1, EtCesA2 and EtCesA3 were isolated with the size of 2940, 3114 and 3123 bp, respectively. Phytohormone regulation of all three EtCesA genes were studied by exogenous application of gibberellic acid, naphthalene acetic acid, indole acetic acid and 2, 4-epibrassinolide in internode tissues derived from three-month-old rooted cuttings. All three EtCesA transcripts were upregulated by indole acetic acid and gibberellic acid. This study demonstrates that the increased cellulose deposition in the secondary wood induced by hormones can be attributed to the upregulation of xylem specific CesAs.

Exogenous GA3 Application Enhances Xylem Development and Induces the Expression of Secondary Wall Biosynthesis Related Genes in Betula platyphylla

“…Germination and embryonic axis growth in Medicago truncatula are inhibited by ABA, and the expression of the CESAs and other cell-wall loosening and expansion genes were also down-regulated by ABA treatment [ 41 ]. In Eucalyptus tereticornis , all three EtCESA transcripts were also up-regulated by GA [ 42 ], suggesting that CESA expression is influenced by hormones. In this study, GA promotion of hypocotyl and xylem expansion may be attributed to the induction of genes involved in cell wall biosynthesis, including CESAs.…”

Expression Patterns and Gene Analysis of the Cellulose Synthase Gene Superfamily in Eucalyptus grandis

“…Eucalyptus that were undergoing secondary cell wall biosynthesis. Sundari and Dasgupta [8] identified three EtCesA genes from E. tereticornis, and revealed high levels of expression in the developing secondary xylem tissues. An increase in the number of CS genes in Eucalyptus was found, indicating that the cellulose synthase families of Eucalyptus are more complex.…”