Effect of zeatin on the growth and indolyl‐3‐acetic acid and abscisic acid levels in maize roots

Abstract

Elongation, indolyl‐3‐acetic acid (IAA) and abscisic acid (ABA) levels, – gas chromatography‐mass spectrometry quantification –, in the elongating zone were analysed for maize (Zea mays L., Cv. LG11) roots immersed in buffer solution with or without zeatin (Z). The effect of Z depends on the initial extension rate of roots. The slower growing roots are more strongly inhibited by Z (10−7−10−5M) and they show a greater increase in IAA and ABA content. When compared to the rapidly growing roots, the larger reactivity of the 'slow’ones cannot be attributed to a higher Z uptake as shown when using [14C]‐Z. It is suggested that Z could regulate root elongation by acting on the IAA and/or ABA level. The comparative action of these two hormones is discussed.