Sequence characterisation of homeobox gene isolated from the cambium xylem tissue of Hevea brasiliensis

One of the key areas identified in the Revised Rubber Strategy at RRIM is the replanting of latex timber clones for the commercial utilisation of heveawood for the wood-based industry. The export performance of heveawood rose from RM 3.7 million in 1993 to RM 3.7 billion in 19981. This figure shows how rubber trees are growing in importance for making furniture, sawn rubber-wood and a new plywood material. In order to ensure constant supply to sustain the timber industry, the emphasis is towards production of more vigorous clones with increased girthing rate (involved in wood production). Hevea brasiliensis is an important industrial tree crop that provides both latex and timber. In trees, wood is derived from the activity of the cambium that differentiates into the xylem elements, but little else is known about the molecular regulation of xylogenesis. Differentiation and development in virtually all organisms studied to date are complex and involve the activity of transcription factors such as those encoded by homeobox (HB) genes. Numerous studies have demonstrated crucial roles for HB genes in the control of a vast diversity of cellular and developmental processes, such as cell fate determination and differentiation in a range of organisms from plants to humans. Such processes involving regulators such as those encoded by HB genes are also presumably at the heart of wood biology, because it is the daughter cells, produced by the cambium, that subsequently differentiate and give rise to the wide variety of wood cells whose unique characteristics and three-dimensional associations define wood properties. Knowledge of what determines the pathway of differentiation that cambium cells undergo is essential to any attempt to design better wood characteristics and improve latex yield. Several researchers have recently reported progress in identifying HB genes in various plant species including tree species2. Two HB genes have been isolated from hybrid aspen and their expression characterised2; one of the genes is specifically expressed at the stage of the xylogenesis process when secondary wall formation is occurring, while the other is expressed in cambial cells and in xylem and phloem cells undergoing radial enlargement. Experiments are currently in progress to determine the exact biological role of these genes in the regulation of secondary xylem formation in hybrid aspen trees. A study was initiated to investigate how wood development in Hevea might be influenced by homeotic genes thought to be associated with wood differentiation. The sequences of the Hevea homeotic genes are reported.

Bibliographic Details

Main Authors:	Arokiaraj, P., Jones, Heddwyn
Format:	conference_item biblioteca
Language:	eng
Published:	CIRAD
Subjects:	F30 - Génétique et amélioration des plantes,
Online Access:	http://agritrop.cirad.fr/513730/ http://agritrop.cirad.fr/513730/1/ID513730.pdf
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