Cytokinins and the CRE1 receptor influence endogenous gibberellin levelsin Medicago truncatula

摘要

Gibberellins (GAs) and cytokinins (CKs) are hormones that play antagonistic roles in several developmentalprocesses in plants. However, there has been little exploration of their reciprocal interactions. Recent work inMedicago truncatula has revealed that GA signalling can regulate CK levels and response in roots. Here, weexamine the reciprocal interaction, by assessing how CKs and the CRE1 (Cytokinin Response 1) CK receptormay influence endogenous GA levels. Real-Time RT-PCR analyses revealed that the expression of key GAbiosynthesis genes is regulated in response to a short-term CK treatment and requires the CRE1 receptor.Similarly, GA quantifications indicated that a short-term CK treatment decreases the GA1 pool in wild-typeplants and that GA levels are increased in the cre1 mutant compared to the wild-type. These data suggestthat the M. truncatula CRE1-dependent CK signaling pathway negatively regulates bioactive GA levels.