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The control of carbon allocation, storage and usage is critical for plant growth and development and is exploited for both crop food production and CO2 capture. Potato tubers are natural carbon reserves in the form of starch that have evolved to allow propagation and survival over winter. They form from stolons, below ground, where they are protected from adverse environmental conditions and animal foraging. We show that BRANCHED1b (BRC1b) acts as a tuberization repressor in aerial axillary buds, which prevents buds from competing in sink strength with stolons. BRC1b loss of function leads to ectopic production of aerial tubers and reduced underground tuberization. In aerial axillary buds, BRC1b promotes dormancy, abscisic acid responses and a reduced number of plasmodesmata. This limits sucrose accumulation and access of the tuberigen protein SP6A. BRC1b also directly interacts with SP6A and blocks its tuber-inducing activity in aerial nodes. Altogether, these actions help promote tuberization underground.

The CONSTANS-FT pathway defines a core module for reproductive transition in both long-day (LD) and short-day (SD) plants. Changes in the transcriptional function of the CONSTANS (CO) protein have been proposed to mediate differential SD activation of FLOWERING LOCUS T (FT) orthologs in SD plants. Potato Andigena genotypes have an obligate SD requirement for tuber formation, and this photoperiodic response correlates with activation of the FT StSP6A gene in leaves. The potato StCOL1 factor represses expression of this mobile tuberization signal, but the control mechanism is poorly understood. Here, we analyzed StCOL1 diurnal oscillation and protein accumulation at different photoperiods and light wavelengths. We observed that the potato StCOL1 gene peaked at dawn and that, in contrast to the Arabidopsis AtCO homolog, the light receptor phyB is necessary for protein stabilization in the light. Reduced StCOL1 levels in RNAi lines strongly correlated with downregulated expression of an additional potato FT family member, StSP5G. Co-regulated StCOL1 and StSP5G expression suggested that StCOL1 activates this target directly rather than controlling StSP6A expression. By hybridization of a universal protein-binding microarray, we established that StCOL1 binds a TGTGGT element, and we found that immunoprecipitated StCOL1 protein fractions were enriched in StSP5G promoter fragments bearing this element. We show that StSP5G represses tuberization in LD conditions and that this FT-like homolog suppresses StSP6A gene expression. Rewiring StCOL1 transcriptional function from direct activation of the StSP6A inducer signal to the control of an FT-like repressor thus mediates the strict SD requirement of Andigena plants for tuberization.

The rapid increase of data centre industry has stimulated the interest of both researchers and professionals in order to reduce energy consumption and carbon footprint of these unique infrastructures. The implementation of energy efficiency strategies and the use of renewables play an important role to reduce the overall data centre energy demand. Information Technology (IT) equipment produce vast amount of heat which must be removed and therefore waste heat recovery is a likely energy efficiency strategy to be studied in detail. To evaluate the potential of heat reuse a unique liquid cooled data centre test bench was designed and built. An extensive thermal characterization under different scenarios was performed. The effective liquid cooling capacity is affected by the inlet water temperature. The lower the inlet water temperature the higher the liquid cooling capacity; however, the outlet water temperature will be also low. Therefore, the requirements of the heat reuse application play an important role in the optimization of the cooling configuration. The experimental data was then used to validate a dynamic energy model developed in TRNSYS. This model is able to predict the behaviour of liquid cooling data centres and can be used to study the potential compatibility between large data centres with different heat reuse applications. The model also incorporates normalized power consumption profiles for heterogeneous workloads that have been derived from realistic IT loads., Peer Reviewed, Postprint (author's final draft)