Effects of root-specific deficiency of each cytokinin receptor AHK2, AHK3, or AHK4 on genome-wide gene expression in shoots and roots of Arabidopsis thaliana

Trans-zeatin (tZ)-type cytokinin (CK) positively regulates leaf size and number by translocating from root to shoot in response to nitrate signals. Our preceding study suggested that CK perception in the root may influence the long-distance transport of tZ-type CKs from root to shoot. However, the underlying mechanism and physiological significance remain unclear. Therefore, we generated grafted plants with the wild-type Col-0 (WT) as the scion and either WT or one of three CK receptor mutants - Arabidopsis histidine kinase (ahk) 2, ahk3, or ahk4 - as the rootstock (scion/rootstock: WT/WT, WT/ahk2, WT/ahk3, and WT/ahk4). We then analyzed the vegetative growth, CK concentrations, and transcriptomes of these grafted plants.