Biology subjects

Velandia, K.

Publications and source records attributed to Velandia, K..

5 recordsLinked to original sources

bioRxiv2025

Parallel CLE peptide signaling pathways control nodulation in pea

Legume root nodulation with nitrogen-fixing bacteria requires precise control via root-shoot-root autoregulation of nodulation (AON). Post-translationally modified root-derived CLAVATA3/Embryo Surrounding Region-Related (CLE) peptides signal through shoot acting leucine-rich repeat receptors (CLAVATAs) to regulate nodule number and this pathway is a target to optimise nodulation. We characterise the AON system in the crop model pea (Pisum sativum L.) and address key gaps in our understanding of AON; the role of parallel signalling pathways, shoot receptor complexes and downstream targets. We use novel mutant combinations, overexpression, grafting, gene expression and careful analysis of infection and nodule organogenesis using GFP-labelled rhizobium. These studies provide evidence that in pea both PsCLE12 and PsCLE13 require arabinosylation via PsRDN1. Perception of PsCLE12 and PsCLE13 in the shoot to suppress the mature nodules in the root requires the pea CLAVATA1 orthologue PsNARK and PsCLV2. However, we found little evidence that PsCLE12 and PsCLE13 suppress infection thread development or that they act via PsTML1 and/or PsTML2, root acting suppressors of nodulation, indicating a role for additional CLE signals. Grafting and double mutant studies indicate that PsNARK can act together with PsCLV2, but also independently, to influences nodulation providing in planta evidence for shoot receptor complexes that control AON. HighlightWe characterise the specific CLE peptide signalling pathway that the model crop legume pea uses to control the number of nitrogen-fixing nodules formed on the root.

plant biology↗

bioRxiv2025

COCHLEATA controls spatial regulation of cytokinin and auxin during nodule development

Root nodules develop in some legumes that host nitrogen-fixing bacteria and likely evolved through modifications of the ancestral lateral root program with plant hormones playing key regulatory roles. Members of the NOOT-BOP-COCH-LIKE transcriptional co-regulator family suppress root identity in legume nodules, including Pisum sativum coch1 that display root-nodule hybrids. However, how COCH/NOOT interacts with hormones to control nodule organogenesis is unclear. We show that PsCOCH (COCHLEATA) is required for spatial tight regulation of auxin and cytokinin during nodule organogenesis and identify key hormone and signalling genes regulated by COCH. COCH suppresses cytokinin levels and response during nodule formation, as cytokinin levels are elevated in Pscoch abnormal nodules and this is mirrored by ectopic cytokinin-responsive TCSn::GUS expression in Pscoch nodule apices, nodule vasculature and in root-like tissue. In contrast, PsCOCH promotes auxin accumulation and precise auxin response patterning in nodules, as Pscoch mutants show significantly reduced auxin levels and severely altered auxin-responsive DR5::GUS expression patterns. RNAseq analysis revealed that Pscoch developing nodules have gene expression profiles more similar to root primordia, with increased expression of defence and auxin response genes (IAA and ARF) and reduced expression of cytokinin biosynthesis genes (IPT3, CYP735A and LOG2) compared to wild type. We found gibberellin is unlikely to act downstream of PsCOCH, as Pscoch and gibberellin-deficient double mutants still form root-nodule hybrids. Ectopic constitutive expression of PsCOCH also produces root-nodule hybrids and we found intriguing links between autoregulation of nodulation pathway and COCH, suggesting that a complex feedback mechanism acts in COCH control of nodule identity.

plant biology↗

bioRxiv2023

Cell layer specific roles for hormones in root development: Gibberellins suppress infection thread progression, promote nodule and lateral root development in the endodermis and interact with auxin and cytokinin

O_LIGibberellins have a profound influence on the formation of lateral root organs. However, the precise role this hormone plays in the cell-specific events during lateral root formation, rhizobial infection and nodule organogenesis, including interactions with auxin and cytokinin, is not clear. C_LIO_LIWe performed epidermal- and endodermal-specific complementation of the severely gibberellin-deficient na pea (Pisum sativum) mutant with Agrobacterium rhizogenes. Gibberellin mutants were used to examine the spatial expression pattern of cytokinin (TCSn) and auxin (DR5) responsive promoters and hormone levels. C_LIO_LIWe found that gibberellins produced in the endodermis promote lateral root and nodule organogenesis and can induce a mobile signal(s) that suppresses rhizobial infection. In contrast, epidermal-derived gibberellins suppress infection but have little influence on root or nodule development. Gibberellins suppress the cytokinin-responsive TCSn promoter in the cortex and are required for normal auxin activation during nodule primordia formation. C_LIO_LIOur findings indicate that gibberellins regulate the checkpoints between infection thread penetration of the cortex and invasion of nodule primordial cells and promotes the subsequent progression of nodule development. It appears that gibberellins limit the progression and branching of infection threads in the cortex by restricting cytokinin response and activate auxin response to promote nodule primordia development. C_LI

plant biology↗

bioRxiv2023

CLE11 and CLE10 Suppress Mycorrhizal Colonisation in Tomato

Symbioses with beneficial microbes are widespread in plants, but these relationships must balance the energy invested by the plants with the nutrients acquired. Symbiosis with arbuscular mycorrhizal (AM) fungi occurs throughout land plants but our understanding of the genes and signals that regulate colonisation levels is limited. Here, we demonstrate that in tomato two CLV3/EMBRYO-SURROUNDING REGION (CLE) peptides, SlCLE10 and SlCLE11, act to suppress AM colonisation of roots. Mutant studies and overexpression via hairy transformation indicate SlCLE11 acts locally in the root to limit AM colonisation. Indeed, SlCLE11 expression is strongly induced in AM colonised roots but SlCLE11 is not required for phosphate suppression of AM colonisation. SlCLE11 may act through as yet uncharacterised signalling pathways, as SlCLE11 does not suppress AM colonisation by acting through two previously characterised receptors with roles in regulating AM colonisation, SlFAB (CLAVATA1 orthologue) or SlCLV2. SlCLE10 appears to play a more minor or redundant role, as cle10 mutants did not influence AM, although the fact that ectopic overexpression of SlCLE10 did suppress colonisation suggests SlCLE10 may play a role in regulating AM colonisation. Our findings show that CLE peptides regulate AM colonisation in the non-legume species tomato.

plant biology↗

bioRxiv2020

The role of CLV signalling in the negative regulation of mycorrhizal colonisation and nitrogen response of tomato

Plants form mutualistic nutrient acquiring symbioses with microbes, including arbuscular mycorrhizal fungi. The formation of these symbioses is costly and plants employ a negative feedback loop termed autoregulation of mycorrhizae (AOM) to limit arbuscular mycorrhizae (AM) formation. We provide evidence for the role of one leucine-rich-repeat receptor like kinase (FAB), a hydroxyproline O-arabinosyltransferase enzyme (FIN) and additional evidence for one receptor like protein (SlCLV2) in the negative regulation of AM formation in tomato. Reciprocal grafting experiments suggest that the FAB gene acts locally in the root, while the SlCLV2 gene may act in both the root and the shoot. External nutrients including phosphate and nitrate can also strongly suppress AM formation. We found that FAB and FIN are required for nitrate suppression of AM but are not required for the powerful suppression of AM colonisation by phosphate. This parallels some of the roles of legume homologs in the autoregulation of the more recently evolved symbioses with nitrogen-fixing bacteria leading to nodulation. This deep homology in the symbiotic role of these genes suggests that in addition to the early signalling events that lead to the establishment of AM and nodulation, the autoregulation pathway might also be considered part of the common symbiotic toolkit that enabled plants to form beneficial symbioses. HighlightWe describe the role of CLV signalling elements in the negative regulation of arbuscular mycorrhizal symbioses of tomato, including influencing nitrate but not phosphate suppression of mycorrhizal colonisation.

plant biology↗