We invite you to a seminar by Prof. Michał Jasiński:

Cytokinins in and out – how ABC driven transport shapes Medicago root morphology upon nitrogen deficiency

Growing evidence has highlighted the essential role of plant hormones, notably cytokinins (CKs), in nitrogen-fixing symbioses, both at early and late nodulation stages. Despite numerous studies suggesting a relevant role of proper CK distribution in legumes during symbiotic nitrogen fixation, our knowledge of the underlying mechanism of CK transport is limited. Recently we have shown in Medicago truncatula that two full-size ABC (ATP-binding cassette) transporters from the G subfamily, functioning as CK importer and exporter, respectively, play an essential role in legume-rhizobia symbiosis and root morphology.

The first one, MtABCG40, is a plasma membrane CK importer. Its expression is root-specific and is induced by nitrogen deprivation and CKs. Our analyses indicate that MtABCG40 exerts a negative impact on lateral root density by decreasing lateral root initiation and enhancing primary root elongation. Moreover, we also observed that this transporter negatively influenced the nodule number. Our results suggest that MtABCG40 action affects CK signalling, which impacts the cellular response to auxin.

The second, MtABCG56, is expressed in roots and nodules and its mRNA levels increase upon treatment with symbiotic bacteria, isolated Nod factor (NF), and CKs, accumulating within the epidermis and root cortex. The MtABCG56 exports bioactive CKs in an ATP-dependent manner over the plasma membrane and its disruption results in an impairment of nodulation.

In my presentation I will tell you more about how these two transporters act in tandem to shape Medicago truncatula root upon nitrogen limitation in soil.

Illustration picture: Medicago truncatula roots with nitrogen-fixing nodules. Source Wikimedia Commons, author Ninjatacoshell, editing Jan Kolář, CC BY-SA 3.0 license.

The seminar will be held at the Institute of Experimental Botany, Czech Academy of Sciences, Rozvojová 263, Prague 6, in the Library room (building B1, 1st floor).