lipids in the stigmatic secretion of datur stramonium l (solanaceae)

the chemical nature of secretion by the stigma and transmitting tissue in datura stramoniumwas studied by light microscopy using sudan black b, coomasie brilliant blue (cbb), toluidine blue,safranin, and pas. the stigmatic secretion reacted positively for lipids. during development, stigmaticcells became separated and intracellular lipids were transferred to intercellular spaces where theygradually migrated to the stigma surface. excretion of the lipids was a continuous process and persistedduring maturity and even in pollinated and opened flowers (post-pollinated). lipid secretion wasassociated with cell autolysis in papillae and in secretory cells of the stigma, particularly in superficiallylocated ones. the transmitting tissue cells also showed glandular activity with the release of apolysaccharide rich substance. the pollen germination and pollen tube growth seem to be closelydependent upon these secretions in datura stramonium. the different nature of the secretion of thestigma (lipids) versus secretion of the transmitting tissue of the style (carbohydrates), supports thehypothesis that the pollen tube metabolism changes from autotrophic to the heterotrophic upon enteringthe transmitting tissue from the stigma surface.