The Toxicity Of Plant Auxin On Vicia Faba

This study investigated the effect of IAA and NAA on micronucleus rate, chromosomal aberration and mitosis index in Vica faba root rip cells, and determined the activity of SOD, POD as well as the change of MDA, discussing the toxic action auxin made to plants. The results are as following:1. IAA, NAA coursed chromosomal aberrationMicronucleus test has been used for evaluating chromosomal aberrations toxic substance generated. In this study, Vicia faba were exposed to different concentrations of IAA and NAA for different times. The results showed that when the concentrations of IAA and NAA increased, micronucleus changed like double-wave, and micronucleus rate are higher than that of control group(p<0.05 or p<0.01).When the concentrations of IAA and NAA are 40mg/L,both micronucleus rate are the highest,20.56%o and 14.62%o. When the concentrations of IAA and NAA are lower than 10mg/L, chromosome tail DNA percentage action rate increased gradually(p<0.05 or p<0.01).The peaks are 13.56% and 8.32%;when the concentrations are higher than 10mg/L, chromosomal aberration rate decreased, lower than control group(p<0.05 or p<0.01).When concentrations of IAA and NAA increased, mitosis index increased, then decreased, and increased again.The results of comet assay showed that tail moment and tail DNA percentage tend to be like micronucleus, higher than control group(p<0.05 or p<0.01).When the concentrations of IAA and NAA are 40mg/L,both tail moment and tail DNA percentage are the highest,15.18% and 14.22,12.07% and 10.33.In conclusion, IAA and NAA can cause cytogenetic toxicity on Vicia faba tip cell.2. IAA, NAA coursed oxidative damageSOD and POD are important antioxidase that involve in many physiological and biochemical process, whose main function is to clear the reactive oxygen species. MDA is the products of membrane lipid peroxidation, whose higher activities of the former two and whose lower of MDA display higher anti-oxidative ability, reflecting higher resistance environment. So they are common indices for evaluating the status of plant redox.The results showed that with the increase of concentrations of IAA and NAA,SOD, POD and MDA increased(p<0.05 or p<0.01),but when concentrations are certain high, three of them begin to decrease.