Plant Growth Regulator Hitches A Protein Ride

Plant shoots get their directive to grow and branch from a family of hormones called cytokinins that are produced in the root system. How these chemical messages make that journey has been a mystery. A team of researchers led by Chang-Jun Liu of Brookhaven National Laboratory has now discovered a transport protein called ABCG14 that’s responsible for relaying the messages (Nat. Commun. 2014, DOI: 10.1038/ncomms4274). Cytokinins, including trans-zeatin, are pivotal in governing overall plant size and can extend plant photosynthesis by delaying leaf aging and death. For those reasons, the team argues that their findings “may open new avenues for modifying various important crops agriculturally, biotechnologically, and horticulturally to increase yields and reduce fertilizer requirements.” Working with a model Arabidopsis plant, the researchers used an array of biochemical and genetic techniques to determine that ABCG14 is expressed in root cell membranes. They also determined that the protein is responsible for exporting cytokinins from the root cells to the plant xylem, an important thoroughfare by which plants transport water and some nutrients to their extremities.