Cytomixis in Maize Microsporocytes.

Caetano, Creucí María; Pagliarini, Maria Suely

doi:10.1508/cytologia.62.4_351

Cited by 30 publications

(8 citation statements)

References 18 publications

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“…And the products of such PMCs in these individuals yield variable sized apparently fertile and sterile pollen grains. Various workers who considered cytomixis to be of considerable significance, the most probable consequence of cytomixis is the formation of hypo-, hyperploid and enucleated PMCs, aberrant microspore tetrads and pollen sterility ( Haroun 1995 , Caetano-Pereira and Pagliarini 1997 , Malallah and Attia 2003 , Haroun et al2004, Singhal et al 2007 , 2008 , 2009a , b , 2010 , Kumar and Singhal 2008 , Singhal and Kumar 2008a , b ).…”

Section: Discussionmentioning

confidence: 99%

Male meiosis, morphometric analysis and distribution pattern of 2× and 4× cytotypes of Ranunculus hirtellus Royle, 1834 (Ranunculaceae) from the cold regions of northwest Himalayas (India)

Kumar¹,

Singhal²

2011

CCG

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In this study, we examined the chromosome number, detailed male meiosis, microsporogenesis, pollen fertility and morphological features and distribution of 2× and 4× cytotypes of Ranunculus hirtellus Royle, 1834. The majority of the populations scored now from cold regions of the northwest Himalayas showed tetraploid (n=16) meiotic chromosome count and one of the populations studied from the Manimahesh hills existed at diploid level (n=8). The individuals of diploid cytotype exhibited perfectly normal meiotic course resulting in 100% pollen fertility and pollen grains of uniform sizes. On the other hand, the plants of the tetraploid cytotype from all the populations in spite of showing normal bivalent formation and equal distribution to the opposite poles at anaphases showed various meiotic abnormalities. The most prominent among these meiotic abnormalities was the cytomixis which involved inter PMC (pollen mother cell) chromatin material transfer at different stages of meiosis-I. The phenomenon of cytomixis induced various meiotic abnormalities which include chromatin stickiness, pycnotic chromatin, laggards and chromatin bridges, out of plate bivalents at metaphase-I, disoriented chromatin material at anaphase/telophase and micronuclei. Consequently, these populations exhibited varying percentages of pollen sterility (24 - 77 %) and pollen grains of heterogeneous sizes. Analysis of various morphometric features including the stomata in 2× and 4× cytotypes showed that increase in ploidy level in the species is correlated with gigantism of vegetative and floral characters and the two cytotypes can be distinguished from each other on the basis of morphological characters. The distribution patterns of the 2× and 4× cytotypes now detected and 2×, 3×, 4× cytotypes detected earlier by workers from other regions of the Indian Himalayas have also been discussed.

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Section: Discussionmentioning

confidence: 99%

Male meiosis, morphometric analysis and distribution pattern of 2× and 4× cytotypes of Ranunculus hirtellus Royle, 1834 (Ranunculaceae) from the cold regions of northwest Himalayas (India)

Kumar¹,

Singhal²

2011

CCG

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“…In general, cytomixis has been detected at a higher frequency in genetically imbalanced species such as hybrids, as well as in apomictic, haploid and polyploid species (see Yen et al, 1993). Among the factors proposed to cause cytomixis are the influence of genes, fixation effects, pathological conditions, herbicides and temperature (see Caetano-Pereira and Pagliarini, 1997). Cytomixis may have serious genetic consequences by causing deviations in chromosome number and may represent an additional mechanism for the origin of aneuploidy and polyploidy (Sarvella, 1958).…”

Section: Discussionmentioning

confidence: 99%

Meiotic behavior of several Brazilian soybean varieties

2000

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Despite the importance of soybeans little cytogenetic work has traditionally been done, due to the small size and apparent similarity of the chromosomes. Fifteen soybean [Glycine max (L.) Merrill] varieties adapted for cultivation in two distinct regions of Brazil were analyzed cytogenetically. A low frequency of meiotic abnormalities was noted in all varieties, although they were not equally affected. Irregular chromosome segregation, chromosome stickiness, cytoplasmic connections between cells, cytomixis and irregular spindles were the main abnormalities observed, none of which had been described previously in soybeans. All of these abnormalities can affect pollen fertility. Pollen fertility was high in most varieties and was correlated with meiotic abnormalities. Although soybean is not a model system for cytological studies, we found that it is possible to conduct cytogenetic studies on this species, though some modifications in the standard methods for meiotic studies were necessary to obtain satisfactory results.

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“…In some meiocytes, such as those represented in Figure 1j and k, only a few chromosomes remained inside the cell, while in others, chromosomes were completely absent (Figure 1l). Cytomixis is a phenomenon widely reported among higher plants, including maize (CaetanoPereira and Pagliarini, 1997;Utsunomiya et al, 2002). The formation of hypoploid and hyperploid cells compromises pollen viability.…”

Section: Resultsmentioning

confidence: 99%

Meiotic behavior as a selection tool in silage corn breeding

Souza

Pagliarini

Scapim³

et al. 2010

Genet. Mol. Res.

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ABSTRACT. In breeding programs, commercial hybrids are frequently used as a source of inbred lines to obtain new hybrids. Considering that maize production is dependent on viable gametes, the selection of populations to obtain inbred lines with high meiotic stability could contribute to the formation of new silage corn hybrids adapted to specific region. We evaluated the meiotic stability of five commercial hybrids of silage corn used in southern Brazil with conventional squashing methods. All of them showed meiotic abnormalities. Some abnormalities, such as abnormal chromosome segregation and absence of cytokinesis, occurred in all the genotypes, while others, including cytomixis and abnormal spindle orientation, were found only in some genotypes. The hybrid SG6010 had the lowest mean frequency of abnormal cells (21.27%); the highest frequency was found in the hybrid P30K64 (44.43%). However, the frequency of abnormal meiotic products was much lower in most genotypes, ranging from 7.63% in the hybrid CD304 to 43.86% in Garra. Taking into account the percentage of abnormal meiotic products and, hence, meiotic stability, only the hybrids CD304, P30K64, SG6010, and P30F53 are recommended to be retained in the breeding program to obtain inbred lines to create new hybrids.

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Cytomixis in Maize Microsporocytes.

Cited by 30 publications

References 18 publications

Male meiosis, morphometric analysis and distribution pattern of 2× and 4× cytotypes of Ranunculus hirtellus Royle, 1834 (Ranunculaceae) from the cold regions of northwest Himalayas (India)

Male meiosis, morphometric analysis and distribution pattern of 2× and 4× cytotypes of Ranunculus hirtellus Royle, 1834 (Ranunculaceae) from the cold regions of northwest Himalayas (India)

Meiotic behavior of several Brazilian soybean varieties

Meiotic behavior as a selection tool in silage corn breeding

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