Abstract
Cadmium is a heavy metal toxic to plants and other organisms. Understanding of cadmium detoxification and tolerance in plants is still insufficient in spite of a number of previous studies in Arabidopsis. We used rice as a model plant to advance understanding of cadmium tolerance in plants because rice is much tolerant to cadmium compared to Arabidopsis.
A genetic screen was performed to isolate cadmium sensitive mutants from 1,200 lines of N-nitoroso-N-methyl urea (MNU) mutagenized rice (cv.Taichung 65), using the root growth on cadmium containing mediums as an index. As a result of the screening, 21 lines were isolated which showed the impaired growth under cadmium treatments. Using the same screening method, we identified one cadmium resistant cultivar from the NIAS world rice core collection. The QTL analysis was conducted using the F2 population of that line crossed with Koshihikari and three QTL were detected with 11 to 17 % of variance of explained. We also conducted the cDNA library screening in yeasts to find rice genes involved in Cd tolerance. Four genes including OsPCS1 were shown to confer cadmium resistance on the cadmium sensitive yeast strain.
