Some effects of analogues of uracil on cell elongation and wall metabolism in excised pea root segments.

Excised root segments of Pisum sativum (L.) cut from the region 2-4 mm behind the root tip were cultured in a 2% sucrose medium containing analogues of uracil and proline. Of several uracil analogues tested only those containing a thiol group (2-thiouracil and 2-thio-6-azauracil) markedly stimulated the growth rate and prolonged the duration of growth of the segments, whereas other uracil analogues which enhanced growth affected only its duration.

Effects of hydroxyproline on the growth of excised root segments of Pisum sativum under aseptic conditions.

The cis and trans isomers of 4-hydroxy-L-proline stimulated the extension growth of excised 2-4 mm pea root segments during culture. Increase in the uptake and subsequent incorporation of [(14)c]leucine into proteins was inhibited by both L-isomers, and so also were changes in chloride uptake capacity and in protein metabolism measured in terms of invertase and peroxidase activities. Changes in [(14)C]proline uptake and incorporation, and in respiration, were unaffected.