PROTEOMIC ANALYSIS OF AMARANTH (AMARANTHUS HYPOCHONDRIACUS L.) LEAVES UNDER DROUGHT STRESS

Amaranth (Amaranthus hypochondriacus L.) is a plant that produces seed with high protein content, is rich on nutraceutical compounds, and can grow under environmental conditions where most of the basic crops are not able to develop. But little is know about the amaranth stress-responsive genes/proteins. The aim of this work was to apply the comparative proteomics approach to study the differential expression of amaranth leaf proteins under drought stress. However, the protein extraction from amaranth tissues is difficult as a result of high endogenous concentrations of interfering compounds; we have made some modifications of the classical trichloroacetic acid-acetone precipitation method to improve the quantity and quality of extracted proteins. Satisfactory and reproducible two-dimensional electrophoresis protein profiles were obtained; the method was also tested forAgave tequilana and Opuntia spp., two more examples of plants that are tolerant to drought stress. Drought-responsive proteins in amaranth leaves were identified by liquid chromatography electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS). The upregulated proteins identified included chloroplast chaperonins involved in refolding and protein complexes protection. Downregulated proteins include Rubisco large subunit, cytochrome b6f, oxygen evolving complexes, and the ascorbate peroxidase mitochondrial. The results have shown that chloroplasts and mitochondria may play a central role in amaranth adaptation to abiotic stress, and further studies should be done at the subcellular level.