AtIPT1AtIPT9

AtIPT1-AtIPT9 refers to nine isopentenyl transferase genes in Arabidopsis thaliana. These enzymes catalyze the transfer of the isopentenyl group from dimethylallyl pyrophosphate (DMAPP) to adenosine phosphate substrates, initiating cytokinin biosynthesis and contributing to the pool of isopentenyladenine–type nucleotides that can be converted to bioactive cytokinins such as isopentenyladenine and its derivatives.

Expression of the AtIPT1-AtIPT9 genes is diverse, with different family members showing tissue- and development-specific patterns and responsiveness to developmental cues and environmental conditions. The family exhibits partial redundancy: single loss-of-function mutants often display only mild phenotypes, whereas higher-order mutants reveal more pronounced effects on shoot and root growth, leaf senescence, and seed development, reflecting altered cytokinin levels. Conversely, overexpression can raise cytokinin content and alter plant architecture.

Biologically, AtIPT enzymes feed into the canonical cytokinin biosynthesis pathway and interact with downstream components such as LOG phosphoribohydrolases, which activate cytokinins, and CKX enzymes, which regulate degradation. The AtIPT gene family functions within broader regulatory networks that integrate light, nutrient status, and stress signals to maintain cytokinin homeostasis and coordinate growth and development in Arabidopsis.