Response of Barley Lines with Structural Rearrangements in Chromosomes 5, 6 and 7 to Limited Nitrogen Nutrition

Spirodela polyrhiza L. Schleid. plants developed anthocyanin (AC) on the abaxial frond surface when grown on Hoagland nutrient solution diluted 1:>=40; AC content was maximum at 1:80 dilution. Till 1:20 dilution there was no or very little AC formation. The formation of AC seems to rely on the availability of excess carbon skeleton in relation to nitrogen in plants. Thus, addition of saccharose to 1:20 diluted medium resulted in a concentration-dependent AC formation. Also fructose, glucose, mannitol, and sorbitol induced AC synthesis. Conversely, urea and ammonium nitrate, when added to the 1:80 diluted medium, suppressed the AC formation. Omission of micronutrients from the growth medium led to the formation of a little amount of AC whereas polyethylene glycol and Cd treatments were ineffective. AC produced under starvation (7 d on distilled water) did not get turned over upon the transfer of plants to nutrient sufficient (1:5 diluted medium) conditions indicating that AC formed does not serve as a reversible C-reserve.