The fungicide captan reduces nuclear DNA content in maize seedlings

Flow cytometric assessment of Cd genotoxicity in three plants with different metal accumulation and detoxification capacities

Cadmium (Cd) is a widespread environmental contaminant, strongly mutagenic and known to cause DNA damage in plants. In this work, flow cytometry (FCM) was applied to determine if in vivo exposure to Cd would induce genotoxic effects at the genome level. The hyper-accumulator Thlaspi caerulescens (J. & C. Presl), the related non-accumulator Thlaspi arvense L. and the accumulator crop species Lactuca sativa L. were germinated in distilled water and grown in modified Hoagland's medium with increasing concentrations of Cd(NO3)2 (0, 1, 10 and 100 microM). After 28 days of exposure, shoot and root growth was recorded and the tissues were harvested for Cd and FCM analysis. In general, roots from treated plants contained higher content of Cd than leaves and growth inhibition was observed in the treated plants. Nuclear DNA content was estimated and the G0/G1 full peak coefficient of variation (FPCV), as an indicator of clastogenic damage, was recorded. In T. arvense and T. caerulescens no significant differences were detected between control and exposed plants. Leaves of L. sativa exposed to 10 microM Cd presented a statistically significant increase in FPCV values in comparison with the control group. Furthermore, roots exposed to 100 microM Cd presented a reduction in nuclear DNA content and an increase in FPCV when compared to the control. FCM data indicates that no major DNA damage was induced on both Cd-exposed Thlaspi species and L. sativa leaves. On the contrary, results obtained with L. sativa roots suggests clastogenic damage in these organs exposed to 100 microM of Cd.

Flow cytometric analyses of intraplant nuclear DNA content variation induced by sticky chromosomes

BACKGROUND

In several plant species, sticky chromosomes are a consequence of genetic mutations or environmental effects on mitosis and meiosis. Sticky chromosomes result in an unequal distribution of genetic material in daughter cells. This unequal distribution is hypothesized to result in an increase in the coefficient of variation (CV) of the G1 peak of dividing cells.

METHODS

The st1 mutant and a nonmutant line in the same genetic background of maize (Zea mays L.) were planted in a soilless mix. A wheat (Triticum aestivum L. em thell.) line was grown in both low and high aluminum-saturated soil. Both plant species were assessed for sticky chromosomes by Feulgen-stained mitotic analysis and flow cytometric analysis of propidium iodide (PI)-stained G1 nuclei.

RESULTS

In the st1 mutant, a significant increase in the number of abnormal anaphase figures was observed. An increase in abnormal mitotic figures was observed in wheat plants grown in aluminum soil. Using flow cytometry, an increase in the CV of the G1/G0 peak was seen in the maize mutant and in wheat grown at high levels of aluminum saturation. This increase correlated with the number of abnormal anaphase cells observed.

CONCLUSIONS

Flow cytometry was sensitive enough to detect the intraplant nuclear DNA variation associated with sticky chromosomes within a plant.