Inhibition of Root Growth and DNA Damage Caused by Cr~(6+) Stress in Wheat Seedlings

The inhibition of root growth and DNA damage resulting from by different concentration of Cr~(6+) were investigated at two growth stages of wheat (Triticum aestivum cv.Xiaoyan No.22) seedlings.The results were as follows:(1) Roots length,roots number,fresh root weight and dry weight of 3-day-old and 10-day-old seedlings all decreased by 5 mg/L Cr~(6+),the root growth of 3-day-old seedlings was more sensitive to Cr~(6+) stress than that of 10-day-old seedlings.(2) The DNA content in root system at two growth stages of seedlings were all reduced by Cr~(6+) concentration;the reduction degree of the DNA content in the root system of 3-day-old seedlings was bigger than that of 10-day-old seedlings in the range of 5~20 (mg/L) Cr~(6+);Cr~(6+)20 mg/L,the DNA content in the root system of 3-day-old seedling was smaller than that of 10-day-old seedling.(3) With the increase of Cr~(6+) concentration,the effect of Cr~(6+) on hyperchromicity of DNA in the root system at two growth stages of seedlings all firstly increased and then declined;the DNA hyperchromicity in the root system of 3-day-old seedlings was bigger than that of control seedlings in the range 5~60 mg/L Cr~(6+),then was smaller than that of control seedlings in the range of 80~100 mg/L Cr~(6+);the DNA hyperchromicity in the root system of 10-day-old seedlings was elevated by Cr~(6+) concentration.