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Shin-Ichi Arimura

Publications and source records attributed to Shin-Ichi Arimura.

5 recordsLinked to original sources
PubMed2026

Highlights from the 14th International Conference for Plant Mitochondrial Biology: Current Trends and Future Directions.

Plant mitochondrial biology is undergoing a rapid transformation driven by advances in genomics, structural biology, quantitative imaging, and genome engineering. Once focused primarily on respiration and bioenergetics, the field now encompasses diverse areas including genome evolution, gene expression, organelle dynamics, stress signaling, metabolism, and biotechnology. The 14th International Conference for Plant Mitochondrial Biology (ICPMB), held in Kagoshima, Japan, from 18-22 May 2026 (Fig. 1), brought together researchers to discuss recent advances across these rapidly expanding research areas. This meeting report summarizes the major scientific advances presented at ICPMB 2026 and highlights emerging directions that are defining the future of plant mitochondrial biology.

Cytoplasmic male sterility (CMS)↗
PubMed2026

Impact of the Simultaneous Loss of the Plastid Envelope-Localized Homologous Pair Ycf10 and DLDG1 in Plant Growth and Photosynthetic Performance.

Ycf10 and DLDG1 are homologous proteins embedded in the chloroplast envelope membranes (EM) and encoded in the plastidial and nuclear genomes, respectively. We previously characterized Arabidopsis dldg1 and tobacco ycf10 mutants, and showed that these proteins mediate proton transport across the EM, thereby influencing ATP synthesis and the non-photochemical quenching (NPQ) induction. However, the consequences of the simultaneous loss of Ycf10/DLDG1 homologs have remained unclear. Here, we generated and analyzed Arabidopsis ycf10 and ycf10-dldg1 double mutants. These mutants exhibited a pale-green phenotype under continuous light conditions, which was complemented by the exogenous addition of NaCl, as previously observed in mutants lacking the plastid EM-localized K+/H+ antiporters KEA1 and KEA2. Both single mutants (ycf10 and dldg1), as well as the ycf10-dldg1 double mutant, showed enhanced NPQ induction compared with wild-type. Furthermore, the ycf10-dldg1 double mutant showed stronger NPQ induction than either single mutant upon transition from dark to light, suggesting that Ycf10 and DLDG1 function independently while playing redundant roles. These mutants also showed reduced stomatal conductance and sugar accumulation compared with the wild-type. Together, these findings indicate that EM-localized DLDG1 and Ycf10 act in concert to maintain chloroplast proton/ion homeostasis, contributing to chloroplast pH homeostasis for sustaining plant growth and efficient photosynthesis.

Photosynthesis↗
PubMed2007

Ethylene promotes submergence-induced expression of OsABA8ox1, a gene that encodes ABA 8'-hydroxylase in rice.

A rapid decrease of the plant hormone ABA under submergence is thought to be a prerequisite for the enhanced elongation of submerged shoots of rice (Oryza sativa L.). Here, we report that the level of phaseic acid (PA), an oxidized form of ABA, increased with decreasing ABA level during submergence. The oxidation of ABA to PA is catalyzed by ABA 8'-hydroxylase, which is possibly encoded by three genes (OsABA8ox1, -2 and -3) in rice. The ABA 8'-hydroxylase activity was confirmed in microsomes from yeast expressing OsABA8ox1. OsABA8ox1-green fluorescent protein (GFP) fusion protein in onion cells was localized to the endoplasmic reticulum. The mRNA level of OsABA8ox1, but not the mRNA levels of other OsABA8ox genes, increased dramatically within 1 h after submergence. On the other hand, the mRNA levels of genes involved in ABA biosynthesis (OsZEP and OsNCEDs) decreased after 1-2 h of submergence. Treatment of aerobic seedlings with ethylene and its precursor, 1-aminocyclopropane-1-carboxylate (ACC), rapidly induced the expression of OsABA8ox1, but the ethylene treatment did not strongly affect the expression of ABA biosynthetic genes. Moreover, pre-treatment with 1-methylcyclopropene (1-MCP), a potent inhibitor of ethylene action, partially suppressed induction of OsABA8ox1 expression under submergence. The ABA level was found to be negatively correlated with OsABA8ox1 expression under ACC or 1-MCP treatment. Together, these results indicate that the rapid decrease in ABA levels in submerged rice shoots is controlled partly by ethylene-induced expression of OsABA8ox1 and partly by ethylene-independent suppression of genes involved in the biosynthesis of ABA.

Base Sequence↗
PubMed2006

The mitochondrial fission regulator DRP3B does not regulate cell death in plants.

BACKGROUND AND AIMS: Recent reports have described dramatic alterations in mitochondrial morphology during metazoan apoptosis. A dynamin-related protein (DRP) associated with mitochondrial outer membrane fission is known to be involved in the regulation of apoptosis. This study analysed the relationship between mitochondrial fission and regulation of plant cell death. METHODS: Transgenic plants were generated possessing Arabidopsis DRP3B (K56A), the dominant-negative form of Arabidopsis DRP, mitochondrial-targeted green fluorescent protein and mouse Bax. KEY RESULTS: Arabidopsis plants over-expressing DRP3B (K56A) exhibited long tubular mitochondria. In these plants, mitochondria appeared as a string-of-beads during cell death. This indicates that DRP3B (K56A) prevented mitochondrial fission during plant cell death. However, in contrast to results for mammalian cells and yeast, Bax-induced cell death was not inhibited in DRP3B (K56A)-expressing plant cells. Similarly, hydrogen peroxide-, menadione-, darkness- and salicylic acid-induced cell death was not inhibited by DRP3B (K56A) expression. CONCLUSIONS: These results indicate that the systems controlling cell death in animals and plants are not common in terms of mitochondrial fission.

Arabidopsis↗