scientificreports OPEN Rhizobial gibberellin negatively regulates host nodule number received: 28 January 2016 accepted: 23 May 2016 Published: 16 June 2016 Yohei Tatsukami1,2 & Mitsuyoshi Ueda1 In legume–rhizobia symbiosis, the nodule number is controlled to ensure optimal growth of the host...