In vitro manifestation of self-incompatibility in Nicotiana alata

JUAN A ROLDÁN; ARIEL GOLDRAIJ

Mar del Plata

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

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Self-incompatibility is studied in a natural population of Nicotiana alata (Solanaceae). Pollination assays were performed to establish the phenotype of compatibility in 8 individuals, evaluating pollen tube migration through the style and fruit production. All plants were self-incompatible and compatible when they were crossed each other. The compatibility genotype is being analyzed by RT-PCR-generated fragments of the S-RNase gene, which is responsible of pollen recognition and rejection.  Self-incompatibility was also studied in an in vitro system by pollen cultivation with pistil extracts. Pollen growth in compatible extract doubled the one reached in incompatible extract. 61% of pollen cells cultivated in compatible extract showed normal morphology and vesicular movement. In contrast, pollen challenged with incompatible extract produced 70% of dead cells and 23% of pollen tubes with morphological alterations. More than 60% of pollen tubes growing in compatible extracts were significantly longer than those growing in incompatible extract. Endomembrane traffic in cultivated pollen tubes was investigated using a fluorescent marker of endocytic route. Pollen tubes challenged with incompatible extracts showed remarkable alterations in the labeling pattern of the apical zone. This was consistent with the decrease in growth and vesicle movement. The in vitro manifestation of self-incompatibility offers a useful system to study the pathway followed by S-RNase when pollen rejection occurs.