Biology subjects

Cookson, S. J.

Publications and source records attributed to Cookson, S. J..

3 recordsLinked to original sources

bioRxiv2026

Genetic dissection of grafting traits reveals regulators of graft union formation in grapevine

Understanding how grafts form has fascinated scientists for over a century, and numerous transcription regulators involved in wound healing, callus formation, and grafting have been identified in model plants. However, the genetic architecture underlying grafting traits remains poorly characterized. To address this gap, we aimed to identify quantitative trait loci (QTLs) associated with grafting success rates and grafting-related traits (including callus formation, mechanical strength of the graft union, and post-grafting growth) in a grapevine rootstock mapping population, Vitis berlandieri x V. rupestris. Although no QTLs were identified for grafting success rate, QTLs were identified for component traits revealing a genetic architecture that would have remained hidden when considering grafting success as a single composite phenotype. By integrating QTL and transcriptome data, we identified regulators potentially mediating grafting-related traits. We then showed that one transcription factor that regulates callus formation and grafting in Arabidopsis potentially has a similar role in grapevine by silencing with exogenous double-stranded RNAs and that exogenous application of methyl jasmonate increases callus development at the graft interface. Candidate transcriptional regulators located within QTLs and evidence from gene silencing and hormone treatments suggest the conservation of regulatory mechanisms underlying wound-induced callus formation across plant species.

plant biology↗

bioRxiv2023

Spatiotemporal changes in secondary metabolites during graft formation in grapevine reveal tissue-specific accumulation of metabolites in necrotic and callus tissues

Grafting is widely used in horticulture, shortly after grafting, callus tissues appear at the graft interface and the vascular tissues of the scion and rootstock connect. The graft interface contains a complex mix of tissues, we hypothesized that each tissue have is own metabolic response to wounding/grafting and accumulate different metabolites at different rates. We made intact and wounded cuttings and grafts of grapevine, and then measured changes in bulk secondary metabolite concentration and used metabolite imaging to study tissue specific responses. We show that some metabolites rapidly accumulate in specific tissues after grafting, e.g. stilbenes accumulate in necrotic tissues surrounding mature xylem vessels and gradually oligomerize over time. We also observe that some metabolites accumulate in the newly formed callus tissue at the graft interface and identify genotype-specific responses. Here we reveal the spatiotemporal dynamics of metabolite changes occurring during graft union formation for the first time. The rapid accumulation of stilbenes in the tissues damaged during the grafting process could be a plant defence mechanism, as stilbenes have antioxidant and anti-fungal capacities. The increasing oligomerization of stilbenes often occurs in response to plant stresses (via unknown mechanisms), but it potentially increases antioxidant activity. Brief summarySecondary metabolites accumulate after wounding and grafting in plants yet we have limited knowledge of tissue specific accumulation patterns and temporal dynamics. We show that stilbenes accumulate specifically in necrotic tissues and oligomerize over the time, whereas other compounds accumulate in the newly formed callus tissues. This suggests that these compounds have different roles in wounding healing and grafting.

plant biology↗

bioRxiv2021

A CLEM approach to access to the ultrastructure at the graft interface in Arabidopsis thaliana

Despite recent progress in our understanding of the graft union formation, we still know little about the cellular events underlying the grafting process. This is partially due to the difficulty of reliably targeting the graft interface in electron microscopy to study its ultrastructure and three-dimensional architecture. To overcome this technological bottleneck, we developed a correlative light electron microscopy approach (CLEM) to study the graft interface with high ultrastructural resolution. Grafting hypocotyls of Arabidopsis thaliana lines expressing YFP or mRFP in the endoplasmic reticulum allowed the efficient targeting of the grafting interface for under light and electron microscopy. To explore the potential of our method to study sub-cellular events at the graft interface, we focused on the formation of secondary plasmodesmata (PD) between the grafted partners. We showed that 4 classes of PD were formed at the interface and that PD introgression into the call wall was initiated equally by both partners. Moreover, the success of PD formation appeared not systematic with a third of PD not spanning the cell wall entirely. Characterizing the ultrastructural characteristics of these failed PD gives us insights into the process of secondary PD biogenesis. We showed that the thinning of the cell wall and the endoplasmic reticulum-plasma membrane tethering seem to be required for the establishment of symplastic connections between the scion and the rootstock. The resolution reached in this work shows that our CLEM method offer a new scale to the study for biological processes requiring the combination of light and electron microscopy.

plant biology↗