Transport of 14C-IAA in Cucurbita maxima: A Comparative Study of Rapid, Non-Polar Movement and Slow, Polar Auxin Transport

The transport of ¹⁴C-IAA has been studied in Cucurbita maxima.IAA fed to the leaf of an intact plant moves rapidly in a non-polarfashion in the phloem. Collection and analysis of exudate fromsevered sieve tubes showed that there was no metabolic conversionor complexing of IAA for several hours. Polar movement of ¹⁴C-IAA in isolated internode segments occursat rates an order of magnitude slower than movement in the phloem.The importance of discrete and isolated channels of hormonetransport, that vary in direction and rates, is briefly discussed.