Abstract
Aim:
To assess the cytological effects of Gamma rays on the pollen mother cells
and post meiotic products of Lepidium sativum Linn. which resulted in
isolation of translocation heterozygote and aneuploid gametes.
Methodology: During the experiment, parameters such as Meiotic
stages, chromosomal structure, and pollen fertility were studied. Fresh seeds
of Garden cress were orderly arranged in plastic and divided into four
groups. The fresh seeds of each group were individually irradiated with 60Gy,
150Gy, 300Gy, 450Gy and 600Gy @ 7.247KGyh-1 in the Floriculture
Laboratory of National Botanical Research Institute (NBRI), Lucknow (India).
The source for gamma ray irradiation was Cobalt-60. The irradiated seeds were
sown in triplicates along with their respective controls.
Results:
Meiotic analysis of pollen mother cells (PMCs) at 300Gy showed translocation
heterozygotes, however, in the control sets, the rate was negligible and
phenotypically the plants were weak and short heighted. The cytological
illustration of chromosomal configuration at diakinesis and metaphase I
exhibited the superiority of tetravalents, bivalent and other forms of
chromosomal associations such as multivalents. The induced translocation
heterozygotes resulted in stickiness at metaphase and anaphase states along
with the formation of bridges at anaphase stage. Due to chromosomal
anomalies, the pollen fertility was reduced to 37.54±0.25% in contrast to
control plants (98.20±0.16%).
Interpretation: The current
research work would be of paramount interest as translocation heterozygote
serves as a source for raising aneuploid offspring having novel genetic
combinations.
Key words: Chromosomal anomalies, Heterozygotes, Lepidium
sativum Linn, Meiosis, Pollen fertility
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