Cell Radiosensitivity Variation in Synchronously-dividing Root Meristems ofPisum Sativum L.andZea Mays L.during the Mitotic Cycle

Abstract

The cell divisions in pea and maize seedling root meristems were synchronized by treatment with 0.03 per cent hydroxyurea for 24 hours. At different times after block cessation (removing seedlings from hydroxyurea), i.e. according to certain phases and subphases of the mitotic cycle, the seedlings were treated with 60Co gamma-radiation at doses from 3 to 32 Gy. Evaluation of seedling radioresistance by the survival of the main root meristem on the tenth day after irradiation led to the following sequence of cell stages in order of increasing resistance. For the pea root meristem: G2, M, late G1, early S, late S, middle S and early G1. For the maize root meristem: late G2, M, G1, early S, early G2, late S and middle S.

Development of rice seedlings grown from pre-hydrated seeds and irradiated with gamma rays

“…The different responses found among cultivars in relation to the parameters analyzed can be explained by the fact that the effects of gamma radiation are influenced by several factors including the gindividuals genotype (BAHL;GUPTA, 1982), the presence of some chemicals substances (KUMAR, 1991), the cell cycle phase (GUDKOV;GRODZINSKY, 1982), the degree of ploidy (BROCK, 1980), the DNA content per haploid genome (PLEWA et al, 1993) and oxygen level (BUMP et al, 1982). Thereby, reducing the biometric parameter settings may be partly due to the fact that the cells which have relatively more chromosomal damage at high irradiation exposures are at a disadvantage and cannot compete well with the normal cells and are thus prevented from making any further contribution (SHAH et al 2008).…”

Clonal Analysis of Cell Lineage Patterns in Plant Development

“…2) The rate ofcell division -It has long been known that the sensitivity ofcells to irradiation is directly related to their rate of cell division (Bergonie and Tribondeau, 1906). One reason for this is that cells tend to be much more sensitive to irradiation during their entry into the Sand M phases of the cell cycle than in the resting, or G 1, phase ofthe cycle (Scott and Evans, 1967;Gudkov and Grodzinsky, 1982;Kowyama, Kawase and Yamagata, 1984). Therefore, spatial variation in the frequency of somatic sectors that cannot be accounted for by a difference in the duration of cell division probably reflects variation in the rate of cell division.…”

Qualidade fisiológica de sementes de arroz submetidas à radiação gama

“…Ciência Rural, v.39, n.5, ago, 2009. CARABIA, 1972, o genótipo dos indivíduos (BAHL & GUPTA, 1982), o modo de exposição do material (IQBAL & ZAHUR, 1975), a presença de algumas substâncias químicas (KUMAR, 1991), a fase do ciclo celular (GUDKOV & GRODZINSKY, 1982), a dosagem de radiação (SANTOS, 1993), o grau de ploidia dos cromossomos (BROCK, 1980), o conteúdo de DNA por genoma haplóide (PLEWA et al, 1993) e o nível de oxigênio (BUMP et al, 1982). Por meio do uso de radiações ionizantes, foram obtidos mutantes com características de maior produtividade, precocidade, menor porte, maior resistência a doenças, pragas e acamamento, que foram utilizados na obtenção de novas variedades de diversas espécies de interesse agronômico (MIKAELSEN, 1971).…”