Cytogenetics and embryology of Eupatorium laevigatum (Compositae)

Genetics and Molecular Biology

Maristela Sanches Bertasso-borges²  James Robert Coleman¹ 

[1] ,Centro Universitário de Rio PretoSão José do Rio Preto SP ,Brazil

关键词: Eupatorium;    apomixis;    plant cytogenetics;    plant embryology;    Asteraceae;   

DOI  :  10.1590/S1415-47572005000100022

来源: SciELO

【 摘 要 】

Embryological studies indicate Eupatorium laevigatum to have Antennaria type diplospory with precocious embryony. The embryo sac is of the Polygonum type and the polar nuclei fuse before anthesis (maturation of the stamens). Endosperm development is autonomous and the central cell divides only after the initial stages of embryo formation. It is estimated that about 10% of the florets in anthesis contain an undivided egg which can be used for sexual reproduction. The study of microsporogenesis revealed abnormalities in chromosome pairing which result in the formation of univalents, bivalents, trivalents and higher polyvalents, with the consequent production of lagging chromosomes, unbalanced nuclei, micronuclei and sterile pollen. We found that, as represented by the material studied, E. laevigatum is an autohexaploid (2n = 6x = 60) in which each chromosome of a basic set of ten chromosomes is repeated six times and that E. laevigatum is an essentialy obligate apomictic.

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