Biology subjects

Shimada, T. L.

Publications and source records attributed to Shimada, T. L..

4 recordsLinked to original sources

bioRxiv2026

Arabidopsis thaliana ACTIN DEPOLYMERIZING FACTORs are novel susceptibility factors for Colletotrichum higginsianum

Colletotrichum higginsianum (Ch) is a hemibiotrophic fungal pathogen that infects Brassicaceae plants, including Arabidopsis thaliana. The molecular mechanisms underlying the Ch-A. thaliana interaction are not fully understood. Particularly, the susceptibility factor against Ch infection remains to be determined. Here, we report that A. thaliana ACTIN DEPOLYMERIZING FACTORs (ADFs), ancient proteins that regulate the organization and dynamics of actin filaments (AFs), function as susceptibility factors during Ch infection. Among 11 ADFs encoded in A. thaliana genome, subclass I ADFs that include ADF1, -2, -3, and -4, express throughout the plant. We found that knockout mutant of ADF4 and transgenic plants in which the expression of all of subclass I members is suppressed (ADF1-4Ri) exhibited increased resistance to Ch. Cytological analyses revealed that both Ch penetration and secondary hyphae formation were suppressed in adf4 and ADF1-4Ri. This enhanced resistance was associated with suppression of Ch-induced AF fragmentation. In addition, we found that PENETRATION 2 (PEN2) plays a critical role in the Ch resistance in adf4 and ADF1-4Ri. Our findings suggest that subclass I ADFs promote AF fragmentation during Ch infection, thereby suppressing PEN2-associated mitochondria accumulation at Ch entry sites. Together, these results raise the possibility that Ch exploits host ADF-dependent actin regulation to facilitate successful infection.

plant biology↗

bioRxiv2026

Identification of tail-binding proteins of Arabidopsis class VIII myosin ATM1 using TurboID proximity labeling and AlphaFold3

Higher plants possess two classes of myosin molecular motors, class XI and class VIII, both unique to the plant lineage. The diverse cellular functions of class XI myosins, including organelle transport and nuclear positioning, have been elucidated largely through systematic identification of cargo adaptor proteins that bind to their globular tail domains (GTDs). In contrast, no proteome-wide screen for class VIII myosin tail-binding proteins has been reported; the few known interacting proteins were each discovered through studies focused on the binding partner rather than on the myosin itself, leaving the full repertoire of class VIII myosin-associated proteins largely unknown. Here, we employed TurboID-based proximity labeling to systematically identify proteins associated with the GTD of the class VIII myosin ATM1 in Arabidopsis thaliana, as this approach covalently biotinylates neighboring proteins in vivo, enabling their identification even after proteolytic degradation during cell lysis. We identified 233 non-redundant candidate ATM1-proximal proteins. Candidates were prioritized by AlphaFold3-based protein complex structure prediction and validated by co-immunoprecipitation. We identified two ATM1-associated proteins: C3H61/AtTZF5, a tandem zinc finger protein involved in mRNA turnover at processing bodies and stress granules; and SFH7, a Sec14-nodulin domain protein that mediates phosphatidic acid transfer from the endoplasmic reticulum to chloroplasts. These findings provide initial evidence linking ATM1 to proteins involved in post-transcriptional gene regulation and interorganellar lipid transport, raising the possibility of previously unrecognized connections between class VIII myosins and these cellular processes.

plant biology↗

bioRxiv2020

Switching secretory pathway direction for organelle acquisition in plants

Eukaryotic cells acquired novel organelles during evolution through mechanisms that remain largely obscure. The existence of the unique oil body compartment is a synapomorphy of liverworts that represents lineage-specific acquisition of this organelle during evolution, although its origin, biogenesis, and physiological function are yet unknown. We found that two Syntaxin 1 paralogs in the liverwort, Marchantia polymorpha, are distinctly targeted to forming cell plates and the oil body, suggesting these structures share some developmental similarity. Oil body formation is under the regulation of an ERF/AP2-type transcription factor and loss of the oil body increased M. polymorpha herbivory. These findings highlight a common strategy for the acquisition of organelles with distinct functions in plants, via periodical switching in secretion direction depending on cellular phase transition.

plant biology↗

bioRxiv2019

A space-saving visual screening method, Glycine max FAST, for generating transgenic soybean

Soybean is an important crop plant for food and biofuel production, and there have been considerable efforts to develop transgenic soybean lines with higher seed oil contents and/or seed yields. However, the process of screening transgenic lines is laborious and requires a large amount of space. Here, we describe a powerful screening method, Glycine max Fluorescence-Accumulating Seed Technology (GmFAST), which is based on a seed-specific fluorescent marker. The marker is composed of a soybean seed-specific promoter coupled to the OLE1-GFP gene, which encodes GFP fused to the oil-body membrane protein OLEOSIN1 of Arabidopsis thaliana. We introduced the marker gene into cotyledonary nodes of G. max Kariyutaka via Agrobacterium-mediated transformation and regenerated heterozygous transgenic plants. OLE1-GFP-expressing soybean seeds can be selected nondestructively using a fluorescence stereomicroscope. Among T2 seeds, the most strongly fluorescent seeds were homozygous. GmFAST uses one-tenth of the growing space required for the conventional method. This space-saving method will contribute to facilitating transformation of soybean. OLE1-GFP was localized specifically to oil bodies in the cotyledon cells of seeds, but it did not affect oil content per seed, the size and density of the oil bodies, or oil composition. One of the homozygous lines (line #8) showed a 44% increase in the seed pod number, which resulted in 41% and 30% increases in seed yield and total oil production, respectively, compared with the wild type. In line #8, OLE1-GFP was inserted into the intron of Glyma13g30950, causing its overexpression. An increase in seed pod number was confirmed in Arabidopsis thaliana plants that overexpressed the Arabidopsis ortholog of Glyma13g30950, E6L1. These results suggest that line #8 is a valuable resource for agricultural and industrial applications. Taken together, GmFAST provides a space-saving visual and non-destructive screening method for soybean transformation, thereby increasing the chance of developing useful soybean lines.

plant biology↗