دانلود رایگان ترجمه مقاله ژن های دخیل در کنترل رشد و تمایز در گیاهان (نشریه الزویر 1993)

ژن های دخیل در کنترل رشد و تمایز در گیاهان

Genes involved in the control of growth and differentiation in plants

Abstract

The mechanisms underlying totipotency, the unique ability of isolated plant cells to regenerate into plants, offer developmental biology a unique challenge. While it has been recognised for some time that phytohormones, such as auxin and cytokinin, play a role in this process by inducing a variety of growth patterns in both isolated cells, unorganised callus and intact plants, the molecular basis of their action remains unknown. The molecular and biochemical analysis of the novel interaction between tumour-inducing soil bacteria and the wounded plant has provided a valuable insight into how plants respond to phytohormones. During tumour formation, the bacteria transfer to the genome of the host plant a variety of genes which either short circuit the normal pathways of accumulation of phytohormones or modify how the plant cell responds to them. In parallel to these studies, we have been investigating plant genes involved directly or indirectly in the mechanism of phytohormone action. Auxin-binding proteins (putative receptors) have been localised in various cellular locations and the genes encoding them are currently undergoing analysis. Recently, a novel form of T-DNA has been devised by which mutant plant cell lines can be generated which grow in culture in the absence of exogenously applied auxin. The tagged genes, which are in effect plant cellular proto-oncogenes, are likely to shed more light on how auxin serves to regulate growth and development.

1 Introduction

Development in plants is characterized by the fact that the fate of most cells is not irreversibly fixed at some relatively early stage during the development of the embryo. Cell differentiation and cell fate determination in most plants are ongoing processes throughout development. As a conseqlence, many organs consist of somatic cells that are potentially ‘totipotent’. In plants, cell division and differentiation are regulated by simple molecules, such as ethylene, sugars, oligosaccharides and metabolites of tryptophan, phenylalanine, adenine, carotenoids, etc. Some of these growth factors have been called ‘phytohormones’, because they are known to be transported from sites of synthesis to sites of action. While recognised as playing an essential role in plant growth and development the molecular action of phytohormones remains unknown. Our interest in the molecular dissection of a developmental process unique to plants sprang initially from our studies on an intriguing interaction between soil bacteria and plants. This system provided us not only with a view of how phytohormones can influence plant development but also the tools with which plant genes involved in this process might be isolated.