Vernalization alters sugar beet (Beta vulgaris) sink and source identities and reverses phloem translocation from taproots to shoots

Martins Rodrigues, C.; Müdsam, C.; Keller, I.; Zierer, W.; Czarnecki, O.; Corral, J. M.; Reinhardt, F.; Nieberl, P.; Sommer, F.; Schroda, M.; Mühlhaus, T.; Harms, K.; Flügge, U.-I.; Koch, W.; Ludewig, F.; Neuhaus, H. E.; Pommerrenig, B.

doi:10.1101/2020.01.28.922906

bioRxiv · 10.1101/2020.01.28.922906

Vernalization alters sugar beet (Beta vulgaris) sink and source identities and reverses phloem translocation from taproots to shoots

Martins Rodrigues, C.·Müdsam, C.·Keller, I.·Zierer, W.·Czarnecki, O.·Corral, J. M.·Reinhardt, F.·Nieberl, P.·Sommer, F.·Schroda, M.·Mühlhaus, T.·Harms, K.·Flügge, U.-I.·Koch, W.·Ludewig, F.·Neuhaus, H. E.·Pommerrenig, B.

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Abstract

During vegetative growth, biennial sugar beets maintain a steep gradient between the shoot (source) and the sucrose-storing taproot (sink). To shift from vegetative to generative growth, they require a chilling phase, called vernalization. Here, we studied sugar beet sink-source dynamics upon cold temperature-induced vernalization and revealed a pre-flowering taproot sink to source reversal. This transition is induced by transcriptomic and functional reprogramming of sugar beet tissue, resulting in a reversal of flux direction in long distance transport system, the phloem. As a key process for this transition, vacuolar sucrose importers and exporters, BvTST2;1 and BvSUT4, are oppositely regulated, leading to re-mobilization of sugars from taproot storage vacuoles. Concomitant changes in the expression of floral regulator genes suggest that the now deciphered processes are a prerequisite for bolting. Our data may thus serve dissecting metabolic and developmental triggers for bolting, which are potential targets for genome editing or breeding approaches.

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Martins Rodrigues, C., Müdsam, C., Keller, I., Zierer, W., Czarnecki, O., Corral, J. M., Reinhardt, F., Nieberl, P., Sommer, F., Schroda, M., Mühlhaus, T., Harms, K., Flügge, U.-I., Koch, W., Ludewig, F., Neuhaus, H. E., Pommerrenig, B.. 2020-01-28. Vernalization alters sugar beet (Beta vulgaris) sink and source identities and reverses phloem translocation from taproots to shoots. https://doi.org/10.1101/2020.01.28.922906

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