Meiotic analysis in induced tetraploids of Brachiaria decumbens Stapf

Abstract

ABSTRACT

Cytoembryological evaluation, meiotic behavior and pollen viability of Paspalum notatum tetraploidized plants

“…It is likely that the expression of apomixis in this duplicated plant is a gene dosage effect. Simioni and Valle (2011) observed the confirmation of the sexual mode of reproduction in three plants obtained by somatic chromosome duplication of sexually reproducing diploid genotype of Brachiaria decumbens.…”

“…Chromosome associations were observed at the diakinesis and metaphase I stages, which are the best stages for visualization of chromosome configurations (Dahmer et al 2008, Simioni andValle 2011). The three plants confirmed tetraploidy (2n=4x=40), as described by Weiler et al (2015).…”

“…All meiotic abnormalities were considered. For the verification of chromosome pairing, analyses were carried out in at least 20 cells per plant at diakinesis and metaphase I stages (Dahmer et al 2008, Simioni andValle 2011).…”

“…Cytological analysis are important tools in breeding programs for the selection of compatible and fertile parents which do not present meiotic abnormalities that may hinder gametes viability (Simioni and Valle 2011). This work allowed observing satisfactory meiotic regularity of the three duplicated plants, and made them viable as parents in the breeding program.…”

Evaluation of Interspecific-Interploid Hybrids (F1) and Back Crosses (BC1) in Hylocereus Species (Cactaceae)

“…Cytological disturbances and anomalous behaviours, such as heavy-walled coenocytes, uncoiled chromosomes, supernumerary chromosomes, production of cross-bridges at second division and the occurrence of globular structures in the microsporocytes, were reported for several species and are strongly associated with a high level of sterility in polyploids, e.g., in the triploid hybrid of Gossypium hirsutum-herbaceum (Beasley, 1940), in the allohexaploid of Phleum pratense (Nath & Nielsen, 1961) and in the tetraploids of Brachiaria decumbens (Simioni & Borges do Valle, 2011). Winge (1917) proposed a theory of "hybridization followed by chromosome doubling" as a mechanism enabling the survival and development of the hybrid zygote by providing each chromosome with a homologue with which to pair.…”