A NEUTRAL/ALKALINE INVERTASE ISOFORM FROM WHEAT IS INDUCED BY COLD, SALT AND OSMOTIC STRESSES

VARGAS WA, SALERNO GL, PONTIS HG

Pinamar

Congreso; 41st Annual Meeting.Argentine Society for Biochemistry and Molecular Biology; 2005

Neutral/Alkaline-Invertases (N/A-Inv) are cytosolic sucrose- hydrolysing enzymes with pH optima in the range 6.8-8.0. They have been identified in plants and cyanobacteria but their role is not known yet. It was suggested they regulate the entry of sucrose into different cytosolic pathways and more recently were reported as involved in stress responses in plants. In the present work we compare the chromatographic pattern (on DEAE-sephacel) of N/ A-Inv of protein extracts from leaves of control and stressed (cold, salt and osmotic) wheat seedling. The results showed that in mature leaves, at least, a novel N/A-Inv isoform is induced in response to cold, salt and osmotic stresses. On the other hand, from wheat EST database a full-length sequence coding for a putative N/A-Inv, (ta- N/A-inv), was identified. We cloned this coding sequence by RT- PCR and expressed it in Escherichia coli as a 6xHis fusion protein using pRSETA vector. The recombinant protein had the expected molecular weight (/ 60 kDa) and was immunodetected by antibodies anti-cyanobacterial N/A-Inv. We studied the expression pattern of ta-N/A-inv in different organs and in response to environmental stresses. The results presented in this work report the identification of the first N/A-Inv from wheat and its expression pattern. We conclude that the expression of ta-N/A-inv is differentially regulated in different organs and in response to environmental stresses. In conclusion, we suggest that N/A-Inv might be involved in stress responses exerted in plants by contributing to the regulation of carbon partitioning in different organs.