HAHB-4 (HELIANTHUS ANNUUS HOMEOBOX 4) EXPRESSION LEVELS IN ARABIDOPSIS TRANSGENIC PLANTS ARE CORRELATED WITH DROUGHT TOLERANCE

GRISELDA FEDRIGO; CARLOS DEZAR; RAQUEL CHAN

Iguazu

Congreso; XL SAIB; 2004

SAIB

  Hd-Zip proteins constitute a family of transcription factors found only in plants. Hahb-4 is a previously described member of sunflower subfamily I. Transgenic Arabidopsis plants that overexpress Hahb-4 under the control of the 35S CaMV promoter were obtained. These plants showed a marked tolerance, improved development, a healthier aspect and higher survival rates that wild-type ones when they were subjected to severe water stress conditions. In this work we have made a comparison between the phenotypes generated by two constructions bearing Hahb-4 under the control of two promoters: the 35S CaMV and Hahb-4 own promoter. Plants transformed with the constitutive promoter show a characteristic phenotype: rounder leaves, shorter stem and a compact inflorescence while plants transformed with the inducible promoter (hahb-4) are very similar to non transformed ones used as controls. Stronger stress tolerance was observed with the 35S CaMV, while the Hahb-4 own promoter region produced a slighter drought tolerance. We concluded that tolerance is correlated with Hahb-4 expession levels and propose the construction of chimeras to obtain optimal results.