2ª REUNIÃO BRASILEIRA DE CITOGENÉTICA
28 a 30 de agosto 2011 • Águas de Lindóia • SP
Cytogenetic analysis applied to an embryologic approach: the case of
pollen sterility in Pitcairnia encholiroides L. B. Smith (Bromeliaceae)
Duarte-Silva, E1; Mendes SP2; De Toni, KLG; 3 Vieira RC4; Kaltchuk-Santos E1; Mariath JEA1
Instituto de Biociências. UFRGS, Porto Alegre, RS;
1
2
Doutoranda. Museu Nacional do Rio de Janeiro. UFRJ. Rio de Janeiro, RJ;
Jardim Botânico do Rio de Janeiro. Rio de Janeiro, RJ;
3
4
Museu Nacional. UFRJ. Rio de Janeiro, RJ
[email protected]
Keywords: meiosis, pollen sterile
Pitcairnia encholirioides bears sterile and fertile anthers at anthesis. We examined if pollen sterility is caused by a cytogenetic
disturbance at meiosis. Flower buds were fixed in ethanol/acetic acid solution (3:1, v/v) for 1-12h with a drop of saturated
aqueous ferric chloride at room temperature, and stored at -200C. Then, digested for 40min at 370C in 20%(v/v) cellulasehemicellulase and 20%(v/v) pectinase aqueous solution, squashed, stained with 1% propionic-carmine and observed in DIC
microscopy. The presence of extranuclear DNA at androspore tetrad stage was investigated through the squashing of the
anthers in DAPI. The analysis was performed in fluorescence microscopy (340-380nm UV filter). The meiotic behavior of
Pitcairnia encholirioides was regular in all stages observed. The chromosome number, counted in diakinesis, is 2n=50 and it
is the first record in this species. At androspore mother-cell stage, no chromosome migration was observed throughout the
cytomictic channels. The chromosomes pair regularly forming 25 bivalents in the equatorial plate. There was regular chromosome segregation at anaphase I and II. DAPI dye analysis showed extranuclear DNA at tetrad stage, without characterize
micronucleous. Otherwise, the bicellular pollen cytoplasm presents great amount of starch, and the androspore extranuclear
DNA belong to proplastids. Sterile pollen degenerates after androspore tetrad release. At fertile anthers, uninucleate androspores are formed, undergo mitosis and develop into bicellular pollen. Then the pollen sterility is not caused by meiosis irregularity, and further embryological studies are necessary to clarify this case.
Financial Support: CNPq, CAPES and FAPERGS
CV024