Biology subjects

Lu, K.-J.

Publications and source records attributed to Lu, K.-J..

6 recordsLinked to original sources

bioRxiv2026

Distinct subcellular localizations of DUF1218 proteins in Marchantia polymorpha and Nicotiana benthamiana reveal two different plasmodesmata-targeting mechanisms

Plasmodesmata are membrane-lined channels connecting plant cells to facilitate intercellular transport of molecules. Although many plasmodesmata-localized proteins have evolved throughout plant evolution, whether they use a conserved targeting system remains unclear. In the bryophyte Marchantia polymorpha, we identified two DUF1218-domain proteins homologous to the Arabidopsis plasmodesmata-localized AtTVA. When ectopically expressed, MpDUF1218-1 localized to plasmodesmata in both Nicotiana benthamiana and M. polymorpha, whereas MpDUF1218-2 formed cytoplasmic puncta in both species. Unexpectedly, AtTVA formed cytoplasmic puncta rather than localizing to plasmodesmata in M. polymorpha. Domain-swap analyses revealed that the first helix of MpDUF1218-1 is crucial for plasmodesmata localization in N. benthamiana, while the first two helices are required in M. polymorpha. In contrast, the second and third helices of AtTVA contribute to its plasmodesmata localization in N. benthamiana. Further domain dissection indicated that other regions of MpDUF1218-1 also contribute to accurate targeting by regulating its distribution among the ER, cytoplasmic puncta, and plasma membrane. Together, our findings suggest that MpDUF1218-1 is targeted by a mechanism shared between the two species, whereas AtTVA relies on a distinct mechanism present in N. benthamiana but absent in M. polymorpha, suggesting the emergence of alternative plasmodesmata-targeting pathways during land plant evolution.

plant biology↗

bioRxiv2024

Exploring The Formation And Permeability Of Plasmodesmata In The Liverwort, Marchantia polymorpha

Plasmodesmata are cell-wall-embedded channels that evolved in the common ancestor of land plants to increase cell-to-cell communication. Whether all the fundamental properties of plasmodesmata emerged and were inherited in all land plants at the same time is unknown. Here we show that the bryophyte Marchantia polymorpha (a non-vascular plant) forms mostly simple plasmodesmata in early-developing gemmae. The complexity of plasmodesmata increases during gemma maturation, and complex plasmodesmata with enlarged cavities are majorly observed in thalli. In contrast to vascular plants, whose simple plasmodesmata can transport monomeric fluorescent proteins, plasmodesmata in Marchantia polymorpha limited their permeability before the juvenile-to-adult transition. In support, callose, a known polysaccharide regulating plasmodesmata permeability in vascular plants, accumulated in most of the Marchantia polymorpha tissues examined. Furthermore, we found that in the apical meristematic region, plasmodesmata allowed the transport of monomeric fluorescent proteins, and this relaxation might correlate with the lower accumulation of callose. Taken together, our study suggests that certain plasmodesmata properties, such as complexity progression and callose accumulation, may have evolved before the divergence between vascular and non-vascular plants.

plant biology↗

bioRxiv2024

The Unexpected Membrane Targeting of Marchantia Short PIN Auxin Exporters Illuminates Sequence Determinants and Evolutionary Significance

The plant hormone auxin and its directional transport are crucial for growth and development. PIN auxin transporters, on account of their polarized distribution, are instrumental in guiding auxin flow across tissues. Based on protein length and subcellular localization, the PIN family is classified into two groups: plasma membrane (PM)-localized long PINs and endoplasmic reticulum (ER)-localized short PINs. The origin of PINs was traced to the alga Klebsormidium, with a single PM-localized long KfPIN. Bryophytes, the earliest land plant clade, represent the initial clade harboring the short PINs. We tracked the evolutionary trajectory of the short PINs and explored their function and localization in the model bryophyte Marchantia polymorpha, which carries four short and one long PIN. Our findings reveal that all short MpPINs can export auxin, and they are all PM-localized with MpPINX and MpPINW exhibiting asymmetric distribution. We identified a unique miniW domain within the MpPINW hydrophilic loop region, which is sufficient for its PM localization. Phosphorylation site mutations within the miniW domain abolish the PM localization. These findings not only identify the essential sequence determinant of PINs PM localization but also provide a unique insight into the evolution of ER-localized PINs. Short MpPINW, which is evolutionarily positioned between the ancestral long PINs and contemporary short PINs, still preserves the critical region essential for its PM localization. We propose that throughout land plant evolution, the unique miniW domain has been gradually lost thus converting the PM-localized short PINs in bryophytes to ER-localized short PINs in angiosperms. IMPORTANTO_LIManuscripts submitted to Review Commons are peer reviewed in a journal-agnostic way. C_LIO_LIUpon transfer of the peer reviewed preprint to a journal, the referee reports will be available in full to the handling editor. C_LIO_LIThe identity of the referees will NOT be communicated to the authors unless the reviewers choose to sign their report. C_LIO_LIThe identity of the referee will be confidentially disclosed to any affiliate journals to which the manuscript is transferred. C_LI GUIDELINESO_LIFor reviewers: https://www.reviewcommons.org/reviewers C_LIO_LIFor authors: https://www.reviewcommons.org/authors C_LI CONTACTThe Review Commons office can be contacted directly at: office@reviewcommons.org

plant biology↗

bioRxiv2022

Divergence of trafficking and polarity mechanisms for PIN auxin transporters during land plant evolution

The phytohormone auxin and its directional transport through tissues play a fundamental role in development of higher plants. This polar auxin transport predominantly relies on PIN-FORMED (PIN) auxin exporters. Hence, PIN polarization is crucial for development, but its evolution during the rise of morphological complexity in land plants remains unclear. Here, we performed a cross-species investigation by observing the trafficking and localization of endogenous and xenologous PINs in two bryophytes, Physcomitrium patens and Marchantia polymorpha, and in the flowering plant Arabidopsis thaliana. We confirmed that the GFP fusion did not compromise the auxin export function of all examined PINs by using radioactive auxin export assay and by observing the phenotypic changes in transgenic bryophytes. Endogenous PINs polarize to filamentous apices, while xenologous Arabidopsis PINs distribute symmetrically on the membrane in both bryophytes. In Arabidopsis root epidermis, bryophytic PINs show no defined polarity. Pharmacological interference revealed a strong cytoskeleton dependence of bryophytic but not Arabidopsis PIN polarization. The divergence of PIN polarization and trafficking is also observed within the bryophyte clade and between tissues in individual species. These results collectively reveal a divergence of PIN trafficking and polarity mechanisms throughout land plant evolution and a co-evolution of PIN sequence-based and cell-based polarity mechanisms.

evolutionary biology↗

bioRxiv2019

Evolution of vascular plants through redeployment of ancient developmental regulators

Vascular plants provide most of the biomass, food and feed on earth; yet the molecular innovations that led to the evolution of their conductive tissues are unknown. Here, we reveal the evolutionary trajectory for the heterodimeric TMO5/LHW transcription factor complex, which is rate-limiting for vascular cell proliferation in Arabidopsis thaliana. Both regulators have origins predating vascular tissue emergence, and even terrestrialization. We further show that TMO5 evolved its modern function, including dimerization with LHW, at the origin of land plants. A second innovation in LHW, coinciding with vascular plant emergence, conditioned obligate heterodimerization and generated the critical function in vascular development. In summary, our results suggest that division potential of vascular cells may have been a major driver in the evolution of vascular plants.

plant biology↗

bioRxiv2017

Regulation of intercellular TARGET OF MONOPTEROS 7 protein transport in the Arabidopsis root

Intercellular communication coordinates hypophysis establishment in the Arabidopsis embryo. Previously, TARGET OF MONOPTEROS 7 (TMO7) was reported to be transported to the hypophysis, the founder cell of the root cap, and RNA suppression experiment implicated its function in embryonic root development. However, it remained unclear what protein properties and mechanisms mediate TMO7 protein transport, and what role the movement plays in development. Here, we report that in the post-embryonic root, TMO7 and its close relatives are transported into the root cap through plasmodesmata in a sequence, but not size dependent manner. We also show that nuclear residence is critical for TMO7 transport, and postulate that modification, potentially phosphorylation, labels TMO7 for transport. Additionally, three novel CRISPR/Cas9-induced tmo7 alleles confirmed a role in hypophysis division, but suggest complex redundancies with close relatives in root formation. Finally, we demonstrate that TMO7 transport is biologically meaningful, as local expression partially restores hypophysis division in a plasmodesmatal protein transport mutant. Our study identifies motifs and amino acids critical for TMO7 protein transport and establishes the importance of TMO7 in hypophysis and root development.\n\nSummary StatementUnique protein motifs, subcellular localization and post-translational modification, rather than protein size regulate plasmodesmatal transport of TMO7 family proteins during Arabidopsis root development.

plant biology↗