Isolation and characterization of two distinct classes of DXS genes in Hevea brasiliensis

Abstract

Two cDNAs encoding two distinct classes of DXSs were cloned from leaves (HbDXS1) and latex (HbDXS2) of Hevea brasiliensis by RT-PCR based methods. HbDXS1 encodes a protein of 720 amino acids, with a high homology to the class I of plant DXS proteins, and HbDXS2 encodes a protein predicted to contain 711 amino acids and with a high homology to the plant DXS class II proteins. Several important motifs and amino acid positions characteristic of DXS proteins are strictly conserved in both new HbDXS proteins. The two HbDXS genes were differentially expressed in various tissues of H. brasiliensis. The transcriptional levels of HbDXS2 were similar in both a high-yielding rubber clone (RRIM 600) and the wild type. Ethephon increased the latex yield and caused a transient increase of expression of the HbDXS2 gene. The expression of HbDXS2 in latex indicates that it may have a primary function in carotenoid biosynthesis rather than for natural rubber.

• Cloning
• 1-deoxy-d-xylulose 5-phosphate synthase
• Hevea brasiliensis
• isoprenoid biosynthesis
• 2C-methyl-d-erythritol 4-phosphate pathway

Acknowledgements

This work was funded in part by a grant from Thailand Research Fund [The Royal Golden Jubilee PhD Scholarship (PHD/0115/2543) to Y.S.], the Graduate Fellowship and the Graduate Research Fund from Prince of Songkla University, and laboratory facilities in the Department of Botany, University of Wisconsin, Madison provided for Y.S. while working with Prof. T.D. Sharkey in 2005. We thank Prof. Ir. Sikke A. Hempenius and Dr Brian Hodgson for reading the manuscript.