Transcriptomics and proteomics analysis of root nodules of model legume plants

Abstract

Leguminosae is a large and economically important family of plants that, because of their capacity to fix atmospheric nitrogen in symbiosis with rhizobia, are essential components of agricultural ecosystems and an important source in the production of food, feed, forage and other compounds with strong industrial and commercial relevance. During the last decade, the 'omics' technologies of legumes especially the model legumes have provided and still provide unprecedented amount of molecular information that has to be understood in a physiological, developmental and organismal context. New technologies, for example high-throughput sequencing, high multiplexed mapping techniques and rapid development of new bioinformatics tools have provided new information about current model systems and emerging new models as well. The latest information on the status of development of genomic resources and of related information in model legumes and some other economically important legume crops are summarized in this review. The infection of the plant root by rhizobia triggers several important events in the root cell, resulting in the formation of a nodule - a nitrogen-fixing compartment. Some of the signal molecules involved in the communication between the symbiotic partners have been studied but little is known about the genes and proteins involved in membrane and protein trafficking and targeting towards the symbiosome-the cellular compartment containing the nitrogen-fixing bacteria in the nodule, which is one of the most important processes in nodule formation and development. The central point of this review is to summarize the recent developments in functional genome, transcriptome and proteome of model legume plants specially Medicago truncatula, Lotus japonicus and Glycine max. A multidisciplinary approach, including plant and bacterial genetics, molecular biology, live cell imaging, biophysics and bioinformatics has been taken to understand the plant-microbe interaction and the biogenesis of root nodules and the genes and proteins involved in nodule formation and efficient nitrogen fixation. Vesicular trafficking plays an important role in rhizobia- root interaction, infection thread formation and the development of root nodules. I have described the role of several small GTP binding proteins in symbiosome formation and root nodule development. Furthermore, there is an increasing need to efficiently convert scientific results into practical applications or products. The economic and environmental costs of the heavy use of chemical N fertilizers in agriculture are a global concern. For this reason legumes could be used as an alternative source for N fertilizers and this would help for cleaning up the environmental pollution caused by chemical fertilizers. Additionally nitrogen-fixing biological systems represent an economically attractive and ecologically sound means of reducing external inputs and improving internal resources. I hope the scientific information given in this review paper could not only be useful to the molecular geneticists and plant breeders but will also assist the agronomists to carry out their research efficiently.