Biological Purification of Eutrophied Water by Transformed Higher Plants.1.Screening of Rapid-Growth Hairy Root Lines of Melon and Their Consumption of Phosphate in Medium

Hairy roots derived from higher plants inoculated with Agrobacterium rhizogenes would be a promising candidate for biological removal of eutrophic nutrients in water, because of their rapid growth and easy regulation of culturing. We obtained 121 hairy root lines in total from infected tobacco and melon leaves, and we selected 60 hairy root lines on the basis of their elongation faster than 1.0 cm/day. Since the efficiency of removing the eutrophic nutrient elements from medium depends on the growth rate, selected lines were cultured in MS medium containing different concentration of 2,4-D. The growth rate of a rapid groth line, KMH-019, increased to about 1,000-fold by the addition of 0.005 yg/m1 2,4-D. The KMH-019 was suggested to be a pomising candidate applicable to a system for biological removal of eutrophic nutrient elements from water.