26 Translational Control in Plants and Chloroplasts

Abstract

The use of plants as a higher eukaryotic model for translation has distinct advantages. The translation lysate from wheat germ has long been used to study protein synthesis. Moreover, because plants exhibit complex development, possess signaling pathways that are conserved in many instances with those of other eukaryotes, and have evolved complex pathogen resistance or stress responses, they are useful for the analysis of translation in differentiated cells types and in responses to internal cues and external conditions. Plants produce many seeds, are inexpensive and easy to grow, and provide a ready source of material for analysis. The genomes of Arabidopsis thaliana and rice have been sequenced and those of several other plant species are nearing completion, enabling cross-species comparisons. Mutations can be easily generated, and if the species is self-pollinated (e.g., Arabidopsis), recessive mutations quickly become homozygous. Insertion mutants resulting in loss of function are available for most genes in Arabidopsis. Arabidopsis and other plant species can be readily transformed for purposes of complementation, introduction of mutant genes, or for RNA interference (RNAi)-mediated repression of gene expression. Because plants are essential to mankind in agriculture, understanding the regulation of translation has direct application to crop improvement. Finally, the study of translation in plants enables cross-kingdom comparisons to determine what features of the machinery and its regulation have been conserved during the evolution of higher eukaryotes and how these have been adapted during the evolution of the unique aspects of plants.

TRANSLATION OF NUCLEUS-ENCODED MRNAs
One significant change in the...