Fig. 4

Simplified cytokinin biosynthesis and signaling pathway in plants, and abundance of cytokinin profiles in aerial tissues derived from crown buds of glyphosate-treated leafy spurge. (a) Adenosine phosphate-isopentenyltransferase (IPT) catalyzes the first step in the biosynthesis of isoprene cytokinins; dimethylallyl diphosphate (DMAPP) or hydroxymethylbutenyl diphosphate (HMBDP) may be used as prenyl donors, and ATP, ADP, or AMP may be used as substrates to produce diverse classes of cytokinins. In cytokinin signaling pathway, hybrid histidine protein kinases (HKs) serve as cytokinin receptors, histidine phosphotransfer proteins (HPTs) transmit the signal from HKs to nuclear response regulators (A- and B-type RRs). Red italic text indicates the genes involved in particular step/s of the pathway. (b) Abundance of cytokinin precursors (c-ZR, t-ZR, dZR, iPR), bioactive cytokinins (t-Z, and dhZ), and cytokinin catabolism products (c-Z, c-ZOG) in aerial tissues derived from crown buds of glyphosate-treated plants. Data represent the mean of four biological replicates obtained from lyophilized tissue (DW), ‘nd’ indicates ‘not detectable’; vertical bars indicate ± SE of the mean