Zinc (Zn) deficiency is a critical problem in human nutrition. Rice is the main source of calories for nearly half of world's population but has the shortcoming, from a nutritional perspective, of being low in Zn and other essential nutrients.

 

Here we performed analyses with cytokinin‐related mutants and transgenic lines to provide unequivocal evidence that cytokinins occupy a key position in controlling Zn status in plants.

 

Transporters responsible for Zn uptake and chelators for the internal transport of Zn were strictly controlled by cytokinins. Moreover, cytokinin metabolism was regulated in a highly dynamic way in response to Zn status, which confers rice to adapt to heterogeneous Zn availability. Subsequently, fine‐tuning of cytokinin metabolism by root‐specific expression of a cytokinin degradation enzyme can improve both Zn nutrient and yield traits. Importantly, X‐ray fluorescence imaging revealed that the increased Zn is broadly distributed from the aleurone layer to the inner endosperm.

 

Our results indicate metabolic control of cytokinin could provide a key for breeding Zn‐enriched rice.