Abstract
It is believed that there are not enough number of mutants available for understanding molecular mechanism of gravity response in root. That is because mutants defective in the signalling pathway of gravity-response may be less defective in gravitropism. To overcome this issue, we used interference of phototropism with gravitropism to screen approximately 100,000 ethylmethanesulfonate (EMS)-mutagenized M2 seedlings of Arabidopsis and obtained 44 lines defective in root gravitropism. One of these was an allele of pgm-1 (phosphoglucomutase-1) mutant that had been reported to be defective in starch synthesis responsible for sedimentation of amyloplasts and to reduce gravity-response not completely. These results suggest that interference of phototropism with gravitropism is useful for detection of reduced gravitropism. We will present the results of genetic analysis of other root gravitropic mutants we isolated using this method.
