Cytokinins are plant hormones, derivatives of adenine with a side chain at the N6-position. They are involved in many physiological processes. While the metabolism of trans-zeatin and isopentenyladenine, which are considered to be highly active cytokinins, has been extensively studied, there are others with less obvious functions, such as cis-zeatin, dihydrozeatin, and aromatic cytokinins, which have been comparatively neglected. To help explain this duality, we present a novel hypothesis metaphorically comparing various cytokinin forms, enzymes of CK metabolism, and their signalling and transporter functions to the comics superheroes Hulk and Deadpool. Hulk is a powerful but short-lived creation, whilst Deadpool presents a more subtle and enduring force. With this dual framework in mind, this review compares different cytokinin metabolites, and their biosynthesis, translocation, and sensing to illustrate the different mechanisms behind the two CK strategies. This is put together and applied to a plant developmental scale and, beyond plants, to interactions with organisms of other kingdoms, to highlight where future study can benefit the understanding of plant fitness and productivity.

• Klíčová slova
• Hulk/Deadpool, aromatic cytokinins, cis-zeatin, cytokinin biosynthesis, cytokinin oxidase/dehydrogenase, cytokinin signalling, cytokinin transport, cytokinins, isopentenyl transferase,
• MeSH
• Arabidopsis metabolismus   MeSH
• biologické modely MeSH
• biologický transport MeSH
• biotest MeSH
• cytokininy metabolismus   MeSH
• fyziologie rostlin * MeSH
• glykosylace MeSH
• hydrolýza MeSH
• kinetika MeSH
• kinetin metabolismus   MeSH
• oxidoreduktasy metabolismus   MeSH
• regulátory růstu rostlin metabolismus   MeSH
• rostliny metabolismus   MeSH
• signální transdukce * MeSH
• vazba proteinů MeSH
• zeatin analogy a deriváty   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• cytokinin oxidase MeSH Prohlížeč
• cytokininy MeSH
• dihydrozeatin MeSH Prohlížeč
• kinetin MeSH
• oxidoreduktasy MeSH
• regulátory růstu rostlin MeSH
• zeatin MeSH

Seed development in flowering plants is a critical part of plant life for successful reproduction. The formation of viable seeds requires the synchronous growth and development of the fruit and the three seed structures: the embryo, the endosperm, the seed coat. Molecular communication between these tissues is crucial to coordinate these developmental processes. The phytohormone auxin is a significant player in embryo, seed and fruit development. Its regulated local biosynthesis and its cell-to-cell transport capacity make of auxin the perfect candidate as a signaling molecule to coordinate the growth and development of the embryo, endosperm, seed and fruit. Moreover, newly formed seeds need nutrients and form new carbon sink, generating high sugar flow from vegetative tissues to the seeds. This review will discuss how auxin and sugars may be considered as signaling molecules to coordinate seed and fruit development.

• Klíčová slova
• auxin, embryo, endosperm, fruit, molecular communication, seed, sucrose,
• MeSH
• cukry metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• ovoce růst a vývoj   metabolismus   MeSH
• semena rostlinná růst a vývoj   metabolismus   MeSH
• signální transdukce * MeSH
• vývoj rostlin * MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• cukry MeSH
• kyseliny indoloctové MeSH