Effect of Sr~(2+) on Mitotic Activity and Chromosomal Behavior in Root Meristem of Allium cepa L.

摘要

The effect of Strontium chloride ranging from 5,10,20,40 and 80 ppm on the mitotic activity and chromosomal behavior in root meristem of Allium cepa for 24h, 48h and 72h was studied. Accumulation of Sr~(2+) in the root meristem reduced the root growthof Allium cepa which was determined using Atomic absorption spectrophotometer (Perkin Elmer) using strontium lamp-68 at 460 nm. Concentrations higher than 20 ppm of Sr~(2+) applied for 24h were toxic for Allium cepa. The non-lethal concentrations of Sr~(2+) showed an inhibitory effect on cell division in root tips of Allium cepa and caused a decrease in their mitotic index values. All treatments changed the frequency of mitotic phases as compared with the control values. Sr~(2+) treatments produced a number of mitotic abnormalities in dividing cells in root tips of plants resulting from its action on the spindle apparatus such as C-metaphases, lagging chromosomes and multipolar anaphases and Binucleate. The induction of chromosomal stickiness and chromosomal aberrations such as bridges and breaks indicates its action on the chromosome. These abnormalities (chromosome breaks and chromosomal bridges at ana-tclophases) indicate true clastogenic potential of the ions tested.