Biology subjects

Considine, M. J.

Publications and source records attributed to Considine, M. J..

7 recordsLinked to original sources

bioRxiv2025

Seasonal changes in the physiology and metabolism of grapevine perennating buds

Grapevine (Vitis vinifera L.) buds undergo seasonal dormancy to survive unfavourable conditions and synchronize growth with environmental cues. While dormancy transitions have been widely studied in temperate woody perennials, the physiological and metabolic dynamics underlying these transitions in grapevine remain poorly understood. Our study investigates seasonal changes in the physiology and metabolism of perennating buds in V. vinifera cv. Cabernet Sauvignon, focusing on dormancy depth, respiration, sugar metabolism, and cell cycle activity. We identified three distinct phases of bud quiescence: (i) para-dormancy (early summer), characterized by active metabolism and high levels of tricarboxylic acid cycle intermediates, shikimate, and myo-inositol; (ii) endo-dormancy (late summer to autumn), where dormancy depth peaked in late summer and was marked by reduced respiration and bud water content, and a sharp decline in hexose levels with a concomitant increase in raffinose; and (iii) eco-dormancy (winter to spring), featuring increased respiration, sugar mobilization (notably sucrose, glucose, and trehalose), and reactivation of cell division, with a shift of cells into the G2 phase. Just prior to bud burst, we observed a significant accumulation of sugar-phosphates, providing evidence that supports their role in promoting bud burst also in grapevine. Our findings provide new insights into the biochemical and physiological regulation of bud dormancy and bud burst, contributing to a deeper understanding of dormancy transitions in perennial crops.

plant biology↗

bioRxiv2024

The physiology of bud dormancy and cell cycle status in grapevine

Evaluating the cell cycle status during dormancy of multicellular organisms is problematic. This is particularly so for woody perennial buds, where dormant and quiescent states are diffuse, and the organ may remain visibly unchanged for six to nine months of the year. In this study, we investigate cell cycle status of dormant grapevine buds by measuring mitotic index using an optimised method developed for grapevine bud tissue. The experimental material showed a dynamic range in the depth of dormancy, declining from 200 days in March to less than 60 days in May and 30 days in August, measured as the time to reach 50% bud burst in forcing conditions. Despite these differences, flow cytometry analysis showed that most nuclei isolated from these buds were arrested at the G1 phase. Ultrastructure analysis of the cells in the region of the shoot apical meristem confirmed that the mitotic activities of buds remained low at all time points, together with the development of starch grains and the relative absence of organelle development. HIGHLIGHTThe cell cycle and ultrastructure data suggest interesting evidence correspond to the growth resumption capacity of grapevine cv. Cabernet Sauvignon buds, i.e., absence of mitosis activities regardless of dormancy depth and starch accumulation irrespective of chilling accumulation.

plant biology↗

bioRxiv2023

Influence of mixed and single infection of grapevine leafroll-associated virus and viral load on berry quality

1Grapevine leafroll disease (GLD) is a viral disease that affects grapevines (Vitis vinifera L.) and has a severe economic impact on viticulture. In this study, the effect of grapevine leafroll-associated viruses (GLRaV) on berry quality was investigated in clones of cultivar cv. Crimson Seedless table grapes infected with GLRaV. RT-PCR confirmed the identity of the clones: clone 3236, infected only with GLRaV-3 (termed Single); clone 3215, infected with GLRaV-3, GLRaV-4 strain 9 and grapevine virus A (termed Mixed), and a viral free clone of the same genetic background of the infected clones (termed Control). The berry quality indices of size, sugar, acidity, and anthocyanin content were measured at harvest maturity. RT-qPCR was used to determine viral load. The study was repeated over two years. A two-way, multivariate analysis of variance (MANOVA) was applied with clone and season as independent variables and the measured berry quality parameters as a dependent variable. All dependent variables were significantly affected by viral infection (Wilks, {lambda}, [2,33] = 0.033895, p-value < 0.001), while only titratable acidity (TA) was affected by season. Average berry dry mass decreased (p-value < 0.001). The water content of both infected clones was greater than that of the control (p-value < 0.001). Both infected clones displayed reduced sugar content as a fraction of the berry dry mass (p-value < 0.001). The anthocyanin and the phenol content of the infected clones were significantly reduced compared to the control clone (p < 0.001, p < 0.05, clone 3236 and clone 3215, respectively). Finally, the viral load was highly variable, and no quantitative relationship between viral load and berry composition was found.

plant biology↗

bioRxiv2022

Hydrogen Cyanamide Causes Reversible G2/M Cell Cycle Arrest Accompanied by Oxidation of the Nucleus and Cytosol in Arabidopsis thaliana Root Apical Meristem Cells

Hydrogen cyanamide (HC) is known to stimulate the production of reactive oxygen species (ROS) and also alter growth through modification of the cell cycle. However, the mechanisms by which HC alters cell proliferation and redox homeostasis are largely unknown. This study used roGFP2 expressing Arabidopsis seedlings to measure the oxidation states of the nuclei and cytosol in response to HC treatment. The Cytrap dual cell cycle phase marker system and flow cytometry were used to study associated changes in cell proliferation. HC (1.5mM) reversibly inhibited root growth during a 24h treatment. Higher concentrations were not reversible. HC did not synchronize the cell cycle. In contrast to hydroxyurea, HC caused a gradual accumulation of cells in the G2/M phase and decline of G1/S phase cells 16 to 24h post-treatment. This was accompanied by increased oxidation of both the nuclei and cytosol. Taken together, HC impairs proliferation of embryonic root meristem cells in a reversible manner through restriction of G2/M transition accompanied by increased oxidative poise.

plant biology↗

bioRxiv2022

Systematic evaluation of chromatin immunoprecipitation sequencing to study histone occupancy in dormancy transitions of grapevine buds

1.The regulation of DNA accessibility by histone modification has emerged as a paradigm of developmental and environmental programming. Chromatin immunoprecipitation followed by sequencing (ChIP-seq) is a versatile tool widely used to investigate in vivo protein-DNA interaction. The technique has been successfully demonstrated in several plant species and tissues; however, it has remained challenging in woody tissues. Here we developed a ChIP method specifically for mature dormant grapevine buds (Vitis vinifera cv. Cabernet Sauvignon). Each step of the protocol was systematically optimised, including crosslinking, chromatin extraction, sonication, and antibody validation. Analysis of histone H3-enriched DNA was performed to evaluate the success of the protocol and identify occupancy of histone H3 along grapevine bud chromatin. To our best knowledge, this is the first ChIP experiment protocol optimised for grapevine bud system.

plant biology↗

bioRxiv2021

The seasonal dynamics of bud dormancy in grapevine suggest a regulated checkpoint prior to acclimation

Grapevine (Vitis vinifera L.) displays wide plasticity to climate and seasonality, ranging from strongly deciduous to evergreen. Understanding the physiology of decisions to grow or quiesce is critical for improved crop management, prediction, and the adaptability of production to alternative climate scenarios. The perenniating bud (N+2) is a major economic unit and focus of study. Here we investigated the physiology and transcriptome of cv. Merlot buds grown in a temperate maritime climate from summer to spring in two consecutive years. The changes in bud respiration, hydration and internal tissue oxygen data were consistent with the transcriptome data. ABA-responsive gene processes prevailed upon the transition to a deep metabolic and cellular quiescence in the bud during autumn. Light, together with hypoxia and redox signalling presided over the resumption of nuclear and cellular growth in the transition to spring. Comparisons with transcriptome data from bud burst studies revealed a number of regulatory candidates for the orderly resumption of growth in spring, including components that may integrate light and temperature signalling. Importantly however, the bud burst forcing data, which is widely used as a measure of bud dormancy, were not consistent with the physiological and transcription data. We hypothesise the existence of a physiological checkpoint following bud set in summer, which if not met results in extreme quiescence. Collectively this is the most integrated developmental dataset of the latent bud of cultivated grapevine, and establishes a platform for systems approaches to study seasonal plasticity. One sentence summaryPhysiology and transcriptome data provide strong evidence of a regulatory checkpoint prior to acclimation and dormancy in latent grapevine buds.

plant biology↗

bioRxiv2018

Physiological regulation of bud burst in grapevine

The physiological constraints on bud burst in woody perennials, including the prerequisite for vascular development remain unresolved. Both light and tissue oxygen status have emerged as important cues for vascular development in other systems, however, light requirement appears to be facultative in grapevine, and the information related to the spatial variability of oxygen in buds is unclear. Here, we analysed apoplastic development at early stages of grapevine bud burst and combined molecular modelling with histochemical techniques to determine the pore size of cell walls in grapevine buds. The data demonstrate that quiescent grapevine buds were impermeable to apoplastic dyes (acid fuchsin and eosin Y) until after bud burst was established. The molecular exclusion size was calculated to be 2.1 nm, which would exclude most macromolecules except simple sugars and phytohormones. In vivo experiments show that grapevine buds were able to resume growth even following excision from the cane, and that the outer scales of grapevine buds may participate in the biochemical repression of bud burst. Furthermore, we demonstrate that the tissue oxygen partial pressure data correlated well with structural heterogeneity within the bud and differences in tissue density. These data consolidate evidence that the meristematic core becomes rapidly oxygenated during bud burst. Taken together, and when put in the context of earlier studies, these data provide solid evidence that the physiological and biochemical events that initiate bud burst reside within the bud, and question the role of long distance signalling in this developmental transition.\n\nHighlightsO_LIThe apoplastic pore size between the grapevine bud and the mother vine is dynamically regulated in the transition to bud burst.\nC_LIO_LIThe molecular exclusion size of the apoplastic connection between the bud and cane is calculated 2.1 nm prior to the initiation of bud burst.\nC_LIO_LIThe structural heterogeneity of the bud explains the spatial variance in tissue oxygen status, and the meristematic core is oxygenated during the initiation of bud burst.\nC_LIO_LILong distance maternal signals are not a requirement for bud burst.\nC_LI

plant biology↗