Biology subjects

Bergonzi, S.

Publications and source records attributed to Bergonzi, S..

3 recordsLinked to original sources

bioRxiv2023

A coordinated switch in sucrose and callose metabolism enables enhanced symplastic unloading in potato tubers

One of the early changes upon tuber induction is the switch from apoplastic to symplastic unloading. Whether and how this change in unloading mode contributes to sink-strength has remained unclear. In addition, developing tubers also change from energy to storage-based sucrose metabolism. Here we investigated the coordination between changes in unloading mode and sucrose metabolism and their relative role in tuber sink strength by looking into callose and sucrose metabolism gene expression combined with a model of apoplastic and symplastic unloading. Decreased callose deposition in tubers is driven by decreased callose synthase activity. Furthermore, changes in callose metabolism and sucrose metabolism are strongly correlated, indicating a well-coordinated developmental switch. Modelling indicates that symplastic unloading is not the most efficient unloading mode per se. Instead, it is the concurrent metabolic switch that provides the physiological conditions necessary to potentiate symplastic transport and thereby enhance tuber sink strength.

plant biology↗

bioRxiv2023

Mobile tuberigen impacts tuber onset synchronization and canopy senescence timing in potato

Yield of harvestable organs is a complex function of photosynthetic output, and sink-strength and timing of competing carbon sinks. In potato (Solanum tuberosum) the effect of tuber onset timing and post-tuberization canopy senescence on growth dynamics and tuber fresh weight are poorly understood. To advance our understanding we compared above- and belowground traits of wildtype plants (WT) with StSP6A, i.e., tuberigen, knockdown plants (SP6Ai) and developed simple computational models to aid interpretation of results. We find that SP6Ai results in a delay of approximately 2 weeks in tuber onset, yet has a 4-to-5-week delayed canopy senescence. Together this results in a prolonged tuber growth phase, with reduced synchronization in tuber onset and a resulting increased variance in tuber sizes, while overall final tuber fresh weight remains similar. Using a leaf and tuber growth model comparing various leaf senescence mechanisms, we find that resource competition, and not a shared signal for tuberization and senescence, is able to explain how delayed tuberization leads to further delayed senescence. Our results point to a role for resource competition in the correlated timing of tuber onset and canopy senescence, as well as a leading role for StSP6A in tuber onset synchronization and tuber size uniformity. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=144 HEIGHT=200 SRC="FIGDIR/small/566204v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@a3abf3org.highwire.dtl.DTLVardef@16de607org.highwire.dtl.DTLVardef@18e3a2org.highwire.dtl.DTLVardef@8c7b5_HPS_FORMAT_FIGEXP M_FIG C_FIG

plant biology↗

bioRxiv2018

PERPETUAL FLOWERING2 coordinates the vernalization response and perennial flowering in Arabis alpina

The floral repressor APETALA2 (AP2) in Arabidopsis regulates flowering through the age pathway. The AP2 orthologue in the alpine perennial Arabis alpina, PERPETUAL FLOWERING 2 (PEP2), was previously reported to regulate flowering through the vernalization pathway by enhancing the expression of another floral repressor PERPETUAL FLOWERING 1 (PEP1), the orthologue of Arabidopsis FLOWERING LOCUS C (FLC). However, PEP2 also regulates flowering independently of PEP1. To characterize the function of PEP2 we analyzed the transcriptomes of pep2 and pep1 mutants. The majority of differentially expressed genes were detected between pep2 and the wild type or between pep2 and pep1, highlighting the importance of the PEP2 role that is independent of PEP1. Here we demonstrate that PEP2 prevents the upregulation of the A. alpina floral meristem identity genes FRUITFUL (AaFUL), LEAFY (AaLFY) and APETALA1 (AaAP1) which ensure floral commitment during vernalization. Young pep2 seedlings respond to vernalization, suggesting that PEP2 regulates the age-dependent response to vernalization independently of PEP1. The major role of PEP2 through the PEP1-dependent pathway takes place after vernalization, when it facilitates PEP1 activation both in the main shoot apex and in the axillary branches. These multiple roles of PEP2 in vernalization response contribute to the A. alpina life-cycle.\n\nHIGHLIGHTThe Arabis alpina APETALA2 orthologue, PERPETUAL FLOWERING2, regulates the age-dependent response to vernalization and it is required to facilitate the activation of the A. alpina FLOWERING LOCUS C after vernalization.

plant biology↗