Implications of soybean metallothioneins in abiotic stress tolerance

GOMEZ, MS; CARRILLO, J; TOMAS,M; CAPDEVILLA, M; BOFILL, R; ATRIAN, S; ANDREO CS

Congreso; SAIB 2013; 2013

Metallothioneins (MTs) are a ubiquitous family of cysteine rich proteins, deeply responsive to a wide range of stress factors. Their main functions are related to heavy metal detoxification and/or general oxidative stress defence. Animal and fungus MTs are highly characterized, by contrast, data on plant metallothioneins are limited, even though many MT isoforms are encoded in their genomes. Considering metallothioneins potential in abiotic stress tolerance/defence in plants of agronomic interest, two soybean MT isoforms were selected for further studies: GmMT1 and GmMT3, most highly expressed isoforms in roots and shoots, respectively. Recombinant soybean MTs, purified from E.coli cells cultured in different metal enriched media, are able to bind Cu, Cd and Zn with high stoichiometries. When these MTs are heterologously expressed in MT-null S. cerevisiae cells, both proteins restore Cu tolerance and improve resistance to oxidative stress, but GmMT3 is best for coping with Cd stress. Moreover, A. thaliana plants expressing soybean MTs under the CaMV35S promoter are able to grow better than wt plants in media with high Cu, Cd, Zn or with hydrogen peroxide. Altogether, our results confirm the promising potential of metallothioneins to palliate different environmental abiotic stresses in plants.