Model Legume Species Research Articles

English

  The recent advances in plant genomics have greatly influenced basic research in many agriculturally important crops. Along with the availability of complete genome information from the model grass species rice and the model legume species M. trucncatula, the functional genomics activities in other crop species will accelerate the genomics studies of forage and turf. Brachypodium distachyon was recently proposed as a new model plant for forage and turf grass genomics studies. The combination of bioinformatics and genomics will enhance our understanding of the molecular functions of forage and turf species. This review focuses on recent advances and applications of functional genomics for large-scale EST projects, global gene expression analyses, proteomics, and metabolic profiling, as well as the impact of functional genomics on improvement of forage and turf crops.   Key words: Functional genomics, forage and turf grasses, ESTs, microarray, proteomics, metabolomics, Medicago truncatula, legume.  

A Krüppel-like transcription factor gene is involved in salt stress responses in Medicago spp.

Legume plants are able to fix nitrogen in symbiotic association with rhizobia and, like many crops, are sensitive to high salt conditions. However, very few molecular markers can be associated to stress tolerance in legume crops. A Kruppel-like transcription factor, Mtzpt2-1, required for the formation of the nitrogen-fixing region, confers salt tolerance to yeast cells. Here, legume responses to salt stresses were studied using alfalfa and its close relative Medicago truncatula, a model legume species. Salt stress induces the Mszpt2-1 gene both in roots and root harbouring nodules. In addition, Sinorhizobium meliloti strains tolerating up to 700 mM NaCl, were used in nodulation assays to assess salt tolerance of the symbiotic response of M. truncatula. Few nodules, mainly in the upper part of the root, could be detected in plants treated with 200 m{M} NaCl, suggesting that nodule initiation was particularly sensitive to salt stress. We have also defined for M. truncatula the threshold of NaCl tolerance after which recovery of stressed plants is irreversible under laboratory conditions. After analysing several times of salt treatment (150 m{M} NaCl), M. truncatula 108R plants stressed for 7 days could not recover (less than 5%), whereas a 4-day treatment allowed at least 75% recovery. Transgenic M. truncatula plants expressing Mtzpt2-1 in antisense configuration are more sensitive to `recover' from salt stress than the wild type. These results identify Mtzpt2-1 as a molecular marker potentially linked to stress tolerance in M. truncatula and suggest its participation in a transcriptional program induced in these plants to cope with salt stress.