EFFECT OF CYTOKININS ON THE ULTRASTRUCTURE OF CHLOROPLASTS AND RuBISCO CONTENT IN WHEAT PLANTS.

CRIADO M.V.; CAPUTO C.; ROBERTS I.N,; BARNEIX A.J.

Mar del Plata, Argentina

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2007

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.

To advance in the knowledge of the role of cytokinins in N remobilization from wheat leaves we investigated the effects of the supply of the synthetic cytokinin bencylaminopurine (BAP) on the RuBISCO content and ultrastructure of chloroplasts. Young wheat plants were supplied with 20µM BAP and after 48 h of treatment the last fully expanded leaves were sampled. RuBISCO were analyzed by SDS-PAGE and its expression by semi quantitative RT-PCR. Amino acids and sugars were measured in phloem exudates. Leaf material was fixed and ultrathin sections were evaluated using a transmission electron microscope. After 48 h of BAP treatment, an increase of proteins and RuBISCO contents were observed, but not differences in its expression was detected. Amino acids and sugars export were inhibited in BAP supplied plants. The chloroplasts were significantly altered by the addition of BAP. A swollen chloroplast was noticed in the BAP plants with more plastoglobuli and starch content and less granal system than the control ones. These results suggest that cytokinin-mediated signaling is preventing amino acids N and sugars export to the phloem, stimulating N accumulation in the chloroplasts.