Recurrence of multiple meiotic abnormalities in maize genotypes from the same origin and their influence on productivity

Abstract

The frequency of meiotic abnormalities among single-, double-and three-way cross experimental hybrids and their parental inbred lines is studied. Among the sixteen inbred lines examined, fifteen originated from populations developed at the National Center of Research in Maize and Sorghum (CNPMS/Embrapa) and one from a population developed at ESALQ (Faculty of Agriculture Luiz de Queiroz of the University of São Paulo). Previous analyses of homozygous and heterozygous maize genotypes from CNPMS populations demonstrated high meiotic instability. The present investigation aims at analyzing the meiotic behavior of different inbred lines obtained from CNPMS populations by another breeding enterprise to verify the presence of the same abnormalities and determine whether the abnormalities might compromise productivity. Analyses showed the presence of some abnormalities described previously, albeit at a lower frequency. The most common abnormalities in homozygous and heterozygous genotypes from CNPMS populations were related to irregular chromosome segregation and to chromosome stickiness. An inbred line from the ESALQ population showed only abnormalities related to irregular chromosome segregation caused by the presence of univalent chromosomes. The Pearson correlation procedure indicated high negative correlation between meiotic abnormalities and productivity.

Meiotic behavior as a selection tool in silage corn breeding

“…Several genes have been reported to cause a lack of cytokinesis in maize (Beadle, 1932;Miller, 1963;Rhoades and Dempsey, 1966). The absence of cytokinesis has also been recorded in some inbred lines and maize hybrids (Defani-Scoarize et al, 1995a,b, 1996Caetano-Pereira et al, 1998;Utsunomiya et al, 2002;Pagliarini et al, 2002;Ricci et al, 2007;Silva et al, 2007).…”

“…Only a few micronuclei (Figure 1e) were found in telophase I. Irregular chromosome segregation (Figure 1f), leading to micronucleus formation, was also recorded in the second division, generating unbalanced gametes, but in low frequency. Irregular chromosome segregation is the most common meiotic abnormality reported among inbred lines and maize hybrids (Pagliarini, 1983(Pagliarini, , 1989Defani-Scoarize et al, 1995a,b, 1996Caetano-Pereira et al, 1998;Utsunomiya et al, 2002;Pagliarini et al, 2002;Ricci et al, 2007;Silva et al, 2007). Chromosome transfer among meiocytes (cytomixis) (Figure 1g-l) was recorded in some plants of the hybrid P30K64, affecting 3.2% of the cells.…”

“…A triad with a restitutional nucleus (Figure 3i) was formed after cytokinesis. Absence of cytokinesis leading to unreduced gamete formation has been widely reported in higher plants (Veillux, 1985;Bretagnolle and Thompson, 1995), and also in maize inbred lines and hybrids (Defani-Scoarize et al, 1995a,b, 1996Caetano-Pereira et al, 1998;Utsunomiya et al, 2002;Pagliarini et al, 2002;Ricci et al, 2007;Silva et al, 2007). Unreduced gametes have great importance in breeding programs when polyploids are desirable.…”

“…Meiosis is a process controlled by a complex genetic system (Gottschalk and Kaul, 1974;Baker et al, 1976;Golubovskaya, 1979Golubovskaya, , 1989Golubovskaya et al, 1993). High meiotic stability has been shown to depend on heterozygosis, and thus, hybrids always show less meiotic abnormalities than do inbred lines (Pagliarini, 1983;Defani-Scoarize et al, 1995a,b, 1996Pagliarini et al, 2002). Correlation between meiotic abnormalities and combining ability in inbred lines of maize was reported by Pagliarini (1989).…”

Effect of forest fragmentation on microsporogenesis and pollen viability in Eugenia uniflora, a tree native to the Atlantic Forest

“…These errors can be conditioned by genetic or environmental factors (Pagliarini, 2002). When an allogamous plant is subjected to self-pollination, the population may become homozygous for many alleles, including those involved in the control of meiosis; this can cause irregularity in microsporogenesis, leading to reduced pollen viability (Ricci et al, 2007).…”