Biology subjects

Correa-Lozano, A.

Publications and source records attributed to Correa-Lozano, A..

3 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↗