Biology subjects

Van de Poel, B.

Publications and source records attributed to Van de Poel, B..

9 recordsLinked to original sources

bioRxiv2025

The last one in the row but decisive: PPDK as a potential key regulator of diurnal deacidification in CAM leaves across varying PPFD and photoperiod conditions

O_LICrassulacean acid metabolism (CAM) plants primarily fix atmospheric CO2 at night and store it as malic acid in their vacuoles. During the light period, vacuolar malate is remobilised and decarboxylated to supply CO2 for Rubisco assimilation. Light intensity and photoperiod are believed to play crucial roles in regulating this process, but their influences on the underlying molecular and biochemical mechanisms remain unclear. C_LIO_LIIn this study, we integrated physiological, biochemical, and molecular approaches to uncover the temporal patterns and light responsiveness of gene transcript and protein abundances, and the activities of enzymes involved in diurnal malate remobilisation in the obligate CAM model species Kalanchoe fedtschenkoi. C_LIO_LIVacuolar malate transport was primarily influenced by the endogenous clock and photoperiod, with KfALMT4 being a more plausible transporter candidate than KftDT. Decarboxylation of the released malate was mainly dictated by photoperiod, with light intensity playing a supplementary role. Both photoperiod and light intensity greatly affected the final processes of CAM photosynthesis i.e. CO2 refixation and pyruvate recycling, with PPDK--the last in line--being the most strictly light-regulated player at the mRNA, protein abundance and activity levels, closely matching malate dynamics. C_LIO_LICollectively, this study revealed the recycling enzyme PPDK as a potential key regulator of light-dependent diurnal deacidification in CAM leaves, rather than the vacuolar malate transport or decarboxylation processes. C_LI

plant biology↗

bioRxiv2024

Kinetic modeling of ethylene biosynthesis and signaling pathways in ripening tomato fruit

O_LIEthylene biosynthesis and signaling are pivotal pathways in various plant aging processes, including fruit ripening. Kinetic models can be used to better understand metabolic pathways, but modeling of the ethylene-related pathways is limited and the link between these pathways remains unsolved. C_LIO_LIA transcriptomics-based kinetic model was developed, consisting of ordinary differential equations describing ethylene biosynthesis and signaling pathways in tomato during fruit development, ripening and post-harvest storage. C_LIO_LIThis model was calibrated against a large volume of transcriptomic, proteomic and metabolic data during on-vine ripening of tomato fruit grown in winter and summer. The model was validated using data on off-vine postharvest ripening. The ethylene biosynthesis pathway under different conditions appeared to be largely driven by gene expression levels. C_LIO_LIThe ethylene-regulation of fruit ripening of a heat tolerant tomato grown in different seasons is identical but with quantitative differences at the targeted omics levels. This is reflected by some of the same parameters with distinct values for summer and winter fruit. The current model is the first attempt to model the ethylene signaling pathway starting from gene expression, the various protein - protein interactions, including the link with ethylene production, internal ethylene levels and its receptors. C_LI

plant biology↗

bioRxiv2024

A vacuolar invertase gene SlVI modulates sugar metabolism and postharvest fruit quality and resistance in tomato

Sugars act as signaling molecules to modulate various growth processes and enhance plant tolerance to various abiotic and biotic stresses. Moreover, sugars contribute to the post-harvest flavor in fleshy fruit crops. To date, the regulation of sugar metabolism and its effect in plant growth, fruit ripening, postharvest quality and resistance remains not fully understood. In this study, we investigated the role of tomato gene encoding a vacuolar invertase, hydrolyzing sucrose to glucose and fructose. SlVI is specifically expressed during the tomato fruit ripening process. We found that overexpression of SlVI resulted in increased leaf size and early flowering, while knockout of SlVI led to increased fruit sucrose content, enhanced fruit firmness, elevated resistance of postharvest fruit to Botrytis cinerea. Moreover, the content of naringenin and total soluble solids was significantly increased in SlVI knockout fruit at postharvest stage. Transcriptome analysis showed a negative feedback regulation triggered by sucrose accumulation in SlVI knockout fruit resulting in a downregulation of BAM3 and AMY2, which are critical for starch degradation. Moreover, genes associated with cell wall, cutin, wax, and flavonoid biosynthesis and pathogen resistance were upregulated in SlVI knockout fruit. Conversely, the expression levels of genes involved in cell wall degradation were decreased in knockout fruit. These results are consistent with the enhanced postharvest quality and resistance. Our findings not only provide new insights into the relationship between tomato fruit sucrose content and postharvest fruit quality, but also suggest new strategies to enhance fruit quality and extend postharvest shelf life.

plant biology↗

bioRxiv2024

Pear (Pyrus communis L. cv. Conference) has shade-tolerant features allowing for consistent agrivoltaic crop yield

Transitioning to a fossil fuel free society requires an increase in solar energy production. However, expanding solar power to farmland competes with food production. Additionally, climate change threatens food security and leads increasingly to yield losses. Agrivoltaics (AV) systems produce solar energy and food on the same field, while sheltering crops. In AV systems, crops grow in a modified environment with reduced solar irradiance, a tempered microclimate and a potential physical cover protecting against hail damage. This research describes pear production under an AV pilot with 24% light reduction for 3 consecutive seasons. AV pear trees yielded 14% less than the reference. Flowering and fruit set was unchanged while AV reduced leaf flavonoid levels. The leaf photosynthetic light response was identical, yet a delayed leaf senescence under AV suggests an adaptation to the modified environment. AV impacted fruit shape, as there was an increase in the number of bottle shaped pears and a reduction in caliber. Other fruit quality traits were broadly unaffected, yet postharvest ethylene production was higher for AV fruit in 2022 than for the control. This study demonstrates that AV systems hold potential for pear production under temperate climates and highlights plant adaptations that make this possible. HighlightPear cultivation in agrivoltaic systems integrates renewable energy and sustainable fruit production. This study provides insights into crop yield, fruit quality, and plant adaptation towards an agrivoltaic environment.

plant biology↗

bioRxiv2024

1-Aminocyclopropane-1-carboxylic acid oxidase determines the fate of ethylene biosynthesis in a tissue-specific way to fine-tune development and stress resilience

Ethylene is involved in several developmental processes and responses towards (a)biotic stress. In seed plants, ethylene is produced from its precursor 1-aminocyclopropane-1-carboxylic acid (ACC) by the enzyme ACC-oxidase (ACO). Despite its key role in ethylene synthesis, the ACO gene family has not yet been fully characterized. We investigated the five ACO members of Arabidopsis thaliana and revealed a tissue-and developmentally specific expression pattern. Furthermore, the five ACO enzymes each have a different capacity to produce ethylene. Combined, this allows for a precise spatial and temporal regulation of ethylene synthesis. At the sub-cellular level, we uncovered that ACOs reside in the cytosol, where ethylene is likely synthesized, but surprisingly also in the nucleus. Using reverse genetics of single and higher order aco mutants we revealed a high degree of gene redundancy and minimal phenotypes. A lack of ethylene synthesis by knocking out all five ACOs did not impair normal vegetative and generative development but did influence processes associated with high rates of ethylene production such as petal abscission. This suggests that ethylene is not a prime regulator of development, but more a moderator. We also showed that the inability to synthesize ethylene impairs some abiotic (nutrient deficiency and metal toxicity) and biotic (Botrytis cinerea) stress responses, similar as plants insensitive towards ethylene, corroborating the role of ethylene in mediating stress responses. In conclusion, the ACO gene family enables plants to fine-tune their ethylene synthesis rates, but a lack their off is not crucial for normal development and stress survival.

plant biology↗

bioRxiv2022

Leaf ontogeny steers ethylene and auxin crosstalk to regulate leaf epinasty during waterlogging of tomato

Developing leaves undergo a vast array of age-related changes as they mature. These include physiological, hormonal and morphological changes that determine their adaptation plasticity towards adverse conditions. Waterlogging induces leaf epinasty in tomato, and the magnitude of leaf bending is intricately related to the age-dependent cellular and hormonal response. We now show that ethylene, the master regulator of epinasty, is differentially regulated throughout leaf development, giving rise to age-dependent epinastic responses. Young leaves have a higher basal ethylene production, but are less responsive to waterlogging-induced epinasty, as they have a higher capacity to convert the root-borne and mobilized ACC into the inactive conjugate MACC. Ethylene stimulates cell elongation relatively more at the adaxial petiole side, by activating auxin biosynthesis and locally inhibiting its transport through PIN4 and PIN9 in older and mature leaves. As a result, auxins accumulate in the petiole base of these leaves and enforce partially irreversible epinastic bending upon waterlogging. Young leaves maintain their potential to transport auxins, both locally and through the vascular tissue, leading to enhanced flexibility to dampen the epinastic response and a faster upwards repositioning during reoxygenation. This mechanism also explains the observed reduction of epinasty during and its recovery after waterlogging in the anthocyanin reduced (are) and Never ripe (Nr) mutants, both characterized by higher auxin flow. Our work has demonstrated that waterlogging activates intricate hormonal crosstalk between ethylene and auxin, controlled in an age-dependent way.

plant biology↗

bioRxiv2022

Waterlogging shifts ontogenic hormone dynamics in tomato leaves and petioles

Waterlogging leads to hypoxic conditions in the root zone that subsequently cause systemic adaptive responses in the shoot, including leaf epinasty. Waterlogging-induced epinasty in tomato has long been ascribed to the coordinated action of ethylene and auxins. However, other hormonal signals have largely been neglected, despite evidence of their importance in leaf posture control. To adequately cover a large group of growth regulators, we performed a tissue-specific and time-dependent hormonomics analysis. This analysis revealed that multiple hormones are differentially affected throughout a 48 h waterlogging treatment, and, more importantly, that leaf development defines a framework in which this hormonal control is regulated. In addition, we could distinguish early hormonal signals that might contribute to fast responses towards oxygen deprivation from those that potentially sustain the waterlogging response. For example, abscisic acid (ABA) levels peak in petioles within the first 12 h of the treatment, while its metabolites only rise much later, suggesting ABA transport is altered. At the same time, cytokinins (CK) and their derivatives drastically decline during waterlogging in leaves of all ages. This drop in CK possibly releases the inhibition of ethylene and auxin mediated cell elongation to establish epinastic bending. Auxins themselves rise substantially in the petiole of mature leaves, but mostly after 48 h of root hypoxia. Based on our hormone profiling, we propose that ethylene and ABA might act synergistically to dynamically fine-tune the balance of IAA and CK in the petiole, ultimately leading to differential growth and epinasty during waterlogging.

plant biology↗

bioRxiv2022

From a different angle: genetic diversity underlies differentiation of waterlogging-induced epinasty in tomato

In tomato, downward leaf bending is a morphological adaptation towards waterlogging, which has been shown to induce a range of metabolic and hormonal changes. This kind of functional trait is often the result of a complex interplay of regulatory processes starting at the gene level, gated through a plethora of signaling cascades and modulated by environmental cues. Through phenotypical screening of a population of 54 tomato accessions in a Genome Wide Association Study (GWAS), we have identified target genes potentially involved in plant growth and survival during waterlogging and subsequent recovery. Changes in both plant growth rate and epinastic descriptors revealed several associations to genes possibly supporting metabolic activity in low oxygen conditions in the root zone. In addition to this general reprogramming, some of the targets were specifically associated to leaf angle dynamics, indicating these genes might play a role in the induction, maintenance or recovery of differential petiole elongation in tomato during waterlogging.

plant biology↗

bioRxiv2022

Ethylene Insensitive 3-Like 2 (EIL2) is a Brassicaceae-specific transcriptional regulator involved in fine-tuning ethylene-dependent hypocotyl elongation, lateral root formation and flowering time in Arabidopsis thaliana

Ethylene signaling directs a pleiotropy of developmental processes in plants. In Arabidopsis, ethylene signaling converges at the master transcription factor Ethylene Insensitive 3 (EIN3), which has five homologs, EIN3-like 1-5 (EIL1-5). EIL1 is most characterized and operates similar as EIN3, while EIL3-5 are not involved in ethylene signaling. EIL2 remains less investigated. Our phylogenetic analysis revealed that EIL2 homologs are only retrieved in the Brassicaceae family, suggesting EIL2 diverged to have specific functions in the mustard family. By characterizing eil2 mutants, we found that EIL2 is involved in regulating ethylene-specific developmental processes in Arabidopsis thaliana, albeit in a more subtle way compared to EIN3/EIL1. EIL2 steers ethylene-triggered hypocotyl elongation in light-grown seedlings and it is involved in lateral root formation. Furthermore, EIL2 takes part in regulating flowering time as eil2 mutants flower on average one day earlier and have fewer leaves. A pEIL2:EIL2:GFP translational reporter line revealed that EIL2 protein abundance is restricted to the stele of young developing roots. EIL2 expression, and not EIL2 protein stability, is regulated by ethylene in an EIN3/EIL1-dependent way. Despite EIL2 taking part in several developmental processes, the precise upstream and downstream regulation of this ethylene- and Brassicaceae-specific transcription factor remains to be elucidated. HighlightEIL2 is an ethylene-dependent transcription factor that evolved exclusively in the mustard family and operates downstream from EIN3/EIL1. EIL2 is involved in fine-tuning hypocotyl elongation, lateral root formation and flowering time in Arabidopsis thaliana.

molecular biology↗