Meiotic behavior and pollen fertility in triploid and tetraploid natural populations of Campuloclinium macrocephalum (Eupatorieae, Asteraceae)
FARCO, G. E.; DEMATTEIS, M.
PLANT SYSTEMATICS AND EVOLUTION
Lugar: Viena; Año: 2014 vol. 300 p. 1843 - 1852
Campuloclinium macrocephalum DC. is aperennial herb widely distributed in the New World andintroduced in South Africa, where it is commonly called??pompom weed??. This species is considered one of themost important weeds of Brazil and one of the problematicinvasive plants of South Africa. The meiotic system can bestudied to assess the ability of a weed to spread, but onlyfew studies on C. macrocephalum have been realized. Inthis study, we examined the meiotic behavior and pollenfertility of 14 natural populations of C. macrocephalumfrom Argentina and Uruguay. Meiotic analysis revealed 2triploid (2n = 3x = 30), 11 tetraploid (2n = 4x = 40) and1 mixed population (2n = 2x = 20, 2n = 4x = 40). Both,triploid and tetraploid specimens showed a widely variablemeiotic behavior with irregular chromosome pairingshowing univalents, bivalents, trivalents (in triploids) andtetravalents (in tetraploids) at diacinesis of first meioticdivision. Different abnormalities were observed, such as:laggard chromosomes, chromatin bridges, and out of platechromosomes at metaphase I. During meiosis I (prophase),some cells showed the phenomenon of cytomixis or chromatintransfer between pollen mother cells. The meioticindexes suggest that only four populations were normallyfertile (over 90 % of fertile pollen), indicating meioticallystable plants. The remaining populations share variablepollen fertility, with triploids ranging from 46.64 to54.83 % and tetraploids varying from 3.54 to 45.30 %. Wesuggest that polyploidy seems to be recurrent in C. macrocephalum,promoting partial sterility of pollen grains,generating large numbers of individuals by apomixispromoting invasion of crop fields. This study presents themeiotic behavior of this weed, these could be useful forfuture studies of biological control in areas with no naturalenemies.