Abstract
It was found that TRG promoted the growth of duckweed Lemna paucicostata 151 in a wide range of concentrations and the effect was the strongest at 20 μM, at which the growth rate was 1.8 times that of the control. The biosynthesis and metabolism of TRG in L. paucicostata 151 was investigated in relation to the plant growth-promoting and flower-inducing activities of the compound to obtain fundamental information on plant growth regulation. Properties of the TRG synthesizing enzyme, nicotinate methyltransferase, were elucidated. Various potent inhibitors to the enzyme were found: TRG (product inhibition), benzoic acid, salicylic acid, picolinic acid, isonicotinic acid, and pyrazinamide. It should be noted that all these compounds except TRG are flowering inducers of the plant. Some relationship between the metabolism of TRG and plant growth regulation is postulated.
