Five cellulose synthase A (CesA) cDNA were cloned from secondary developing xylem tissue of Eucalyptus camaldulensis tree designated EcCesA1 to EcCesA5. The EcCesA cDNA fragments ranged from 2,937 bp to 3,258 bp in length, encoding 979 to 1086 amino acids. Their identity/similarity between each other was around 59-69 %/69-79 %. Sequence analysis identified conserved domain and class-specific regions (CSRs) of cellulose synthase A, consistent with their phylogenetic clustering into different CesA clades. Quantitative real-time PCR (qPCR) and in situ hybridization (ISH) analyses suggested that EcCesA4 and EcCesA5 exhibited no clear tissue preference, and are likely associated with primary cell wall development. Expression of EcCesA1, EcCesA2 and EcCesA3 increased during stem development, consistent with a role in secondary cell wall formation. All these five genes expressed more commonly in xylem tissues with an exception of EcCesA3 expression which was also observed in other tissues as well as in different growth stages. In 4CL1-suppressed transgenic E. camaldulensis trees, the transcripts of EcCesA1, EcCesA2 and EcCesA3 were reduced in contrast to EcCesA4 and EcCesA5.
Journal of Plant Biochemistry and Biotechnology, v.23 n.2, pp.199-210