Helia ◽  
2001 ◽  
Vol 24 (35) ◽  
pp. 39-46
Author(s):  
Orhan Arslan ◽  
Şenol Bal ◽  
Nilgün Venice ◽  
Semra Mirici

SUMMARYIn this study, mitotic effects of gamma rays on Ekiz 1 variety belonging to Helianthus annuus L. (2n= 34) in the M0 (first irradiated seeds), M1 and M2 generations have been investigated. Seeds (M0) were irradiated with gamma rays at 10, 20, 30, 40 and 50 kR doses. Percentage of total abnormalities in the M0, M1 and M2 generations increased parallel to the increasing dose of radiation. These abnormalites have been observed as C-metaphase, chromosome stickiness, laggards and bridges with or without fragment. Mitotic index (M.I.) in the M0, M1 and M2 generations has decreased parallel to the dose increase. When the generations are compared, both the amounts of decrease in mitotic index and in the percentage of mitotic abnormalities were mostly observed in M0.


1986 ◽  
Vol 8 (3) ◽  
pp. 401-411 ◽  
Author(s):  
Mary Ann Dowd ◽  
Mary Esther Gaulden ◽  
Bertha L. Proctor ◽  
G. Burton Seibert

2000 ◽  
Vol 23 (3) ◽  
pp. 623-631 ◽  
Author(s):  
Nilton Cesar Pires Bione ◽  
Maria Suely Pagliarini ◽  
José Francisco Ferraz de Toledo

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.


Vivências ◽  
2020 ◽  
Vol 16 (31) ◽  
pp. 123-136
Author(s):  
Cristiane Deuner ◽  
Alison Munhos ◽  
Vera Lúcia Bobrowski ◽  
Sidnei Deuner ◽  
Andréia da Silva Almeida ◽  
...  

Salinity can affect cell division and cause chromosomal abnormalities such as the formation of micronuclei, chromosome stickiness, c-mitosis and multipolar anaphases. Plants react to salt stress with morphological, biochemical, physiological, cellular and molecular adjustments. The aim of this study was to evaluate the effect of different leaf extract concentrations of purple lettuce on the cytogenetic activity of lettuce roots, cv. Regina, from seeds subjected to salt stress. Four extract concentrations of purple lettuce (0, 50, 100 and 150 g lettuce leaves L-1 water)and five concentrations of sodium chloride (0, 30, 60, 90 and 120 mM) were tested, constituting 20 treatments, with distilled water for a negative control. The analyses were of mitotic index (MI), phase index of mitosis (prophase, metaphase, anaphase and telophase) and the presence of chromosomal aberrations. Salt reduces the mitotic index and all index phases of the lettuce roots. The purple lettuce extract does not affect the mitotic index, reduces the cell index in prophase and increases the cells in telophase of lettuce roots. The purple lettuce extract and salt cause chromosomal abnormalities in lettuce root cells; however, a smaller number of mutations is found by applying 100 g L-1 extract.


2009 ◽  
Vol 66 (5) ◽  
pp. 691-696 ◽  
Author(s):  
Claudicéia Risso-Pascotto ◽  
Maria Suely Pagliarini ◽  
Cacilda Borges do Valle

Some African species of Brachiaria have been introduced into the Americas and became the most important forage for pastures in the tropics. New cultivars can be obtained either from direct selections from the natural existing variability in the germplasm collections or from interspecific hybridizations. Polyploidy is predominant in the genus Brachiaria and correlated with apomixis which complicates hybridization. The objective of cytological studies underway on the Brachiaria germplasm collection at Embrapa Beef Cattle is to determine the chromosome number and meiotic behavior of accessions. For the breeding of Brachiaria species, compatible sexual and apomictic accessions need to be identified. Microsporogenesis was evaluated in two accessions of Brachiaria bovonei (BO01 and BO05) and one accession of B. subulifolia (SU01). BO01 is pentaploid (2n = 5x = 45), BO05 is tetraploid (2n = 4x = 36), and SU01 is hexaploid (2n = 6x = 54), derived from x = 9. Meiotic abnormalities typical of polyploids, characterized by precocious chromosome migration to the poles in metaphases, laggard chromosomes in anaphases, and micronuclei in telophases and tetrads, were recorded in high frequency in all the accessions generating unbalanced gametes. Both accessions of B. bovonei presented chromosome stickiness. The results are discussed in the view of the Brachiaria breeding program objectives.


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