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|Type:||Artigo de periódico|
|Title:||Microsporogenesis And Pollen Morphology Of Mucuna Japira Azevedo, Agostini & Sazima And M. Urens (l.) Medikus|
De Azevedo Tozzi A.M.G.
|Abstract:||Low pollen quality can be associated with irregularities of species reproduction. Microsporogenesis, chromosome number, meiotic behaviour and meiotic index were investigated in Mucuna japira and M. urens in order to ascertain whether pollen could limit fertilization events, once M. japira shows low fruit set (2.7%), while in M. urens the fruit set is much higher (11.0%), thus a high rate of fruit abortion occurs in M. japira. Both species have dimorphous anthers, and the timing of microsporogenesis and pollen release varies in the two sets of stamens. The microspore mother cells are vacuolated, with granulose cytoplasm, prominent nucleus and nucleolus and a callose wall. Tetrads are tetrahedric with a thick callose wall. Mature pollen grains are tricolpate, the exine sculpture is reticulated and its viability is 92.2% for M. japira and 97.8% for M.urens. The chromosome number of these species is n=11, being this the first report for both of them, and further this number corroborates the position of Mucuna in Phaseoleae. The most frequent abnormalities recorded at the tetrad stage of both species were pentads, empty/or irregular tetrads with cells of different sizes. The meiotic index for both species is above 90. Once microsporogenesis, pollen morphology and pollen grain viability are normal and similar in M. japira and in M. urens these features are not related with the high rate of fruit abortion of M. japira.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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