Meiotic restitution mechanisms involved in the formation of 2n pollen in Agave tequilana Weber and Agave angustifolia Haw

Abstract

A cytological analysis of the microsporogenesis was carried out in the Agave tequilana and A. angustifolia species. Several abnormalities such as chromosomal bridges, lagging chromosomes, micronuclei, monads, dyads and triads were found. The morphological analysis of the pollen, together with the above-mentioned 2n microspores, allowed us to confirm the presence of 2n pollen as well as its frequency. In both A. tequilana and A. angustifolia two different mechanisms were observed: the first mechanism, a failure in the cytokinesis in meiosis II caused the formation of dyads with two 2n cells and triads containing two n cells and one 2n cell; the second mechanism, involves an abnormal spindle, which caused the formation of triads with two n cells and one 2n cell. Likewise, the presence of monads was detected in both species, these, might be caused by a failure of the cytokinesis in both meiotic divisions. This is the first report about the presence of a Second Division Restitution mechanism (SDR) which causes the formation of 2n pollen in the genus Agave. The genetic implications of the presence of 2n pollen in the genus Agave are discussed.

Meiotic instability inAegilops cylindrica: a comparison with stable meiosis inTriticum monococcumsubsp.aegilopoides

“…cylindrica and causes restitution of the nucleus at first meiotic division (Figure 2h). Likewise, formation of 2n microspores originated from the lack of cytokinesis at the first, second and/or both of divisions has already been reported in some plant taxons, such as Paspalum, Brachiaria, Solanum, Lolium, Medicago and Gramineae (Gomez-Rodriguez et al 2012).…”

The effect of cross direction and ploidy level on phenotypic variation of reciprocal diploid and triploid mandarin hybrids

“…(Ortiz 1997), Dactylis (Maceira et al 1992), Rosa spp. (Zlesak 2009), maize (Rhoades and Dempsey 1966), Populus (Liesebach et al 2015), Agave (Gomez et al 2012) and Citrus (Frost et Soost 1968;Esen and Soost 1971;Geraci et al 1975;Cuenca et al 2015a;Rouiss et al 2017a).…”

Chromatid Abnormalities in Meiosis: A Brief Review and a Case Study in the Genus Agave (Asparagales, Asparagaceae)

“…Meiotic cell division is the key point process in the sexual reproduction of most of animal and plant species, through which haploid gametes are generated, and includes two successive divisions of the nucleus, where the irst division is reductional and the second is equational; a failure in any or in both of these cell divisions produces chromosomal accidents which will be relected in gamete viability or mutations that will appear in the progeny [13]. The objective of meiosis is to produce haploid gametes from original diploid cells and starts with the replication of DNA that produces four chromatids of each type of chromosome, two from the female parent and two from the male parent.…”