Biology subjects

Katsuhama, N.

Publications and source records attributed to Katsuhama, N..

4 recordsLinked to original sources

bioRxiv2026

OsPATROL1 overexpression accelerates stomatal opening to enhance photosynthetic induction and growth under fluctuating light in rice

Slow stomatal opening after increases in irradiance constrains carbon gain under fluctuating light, yet stomatal kinetics remain an underexplored target for crop improvement. Here, we investigated Oryza sativa PROTON ATPASE TRANSLOCATION CONTROL 1 (OsPATROL1), which encodes a Munc13-like protein implicated in stomatal regulation in Arabidopsis thaliana. OsPATROL1 overexpression had modest, condition-dependent effects on steady-state gas exchange and did not alter stomatal morphology or biochemical traits. In contrast, it consistently accelerated stomatal opening and photosynthetic induction, reducing the stomatal conductance time constant during induction by 41-43%. During 12 h of simulated natural fluctuating light, OsPATROL1-overexpressing plants maintained higher stomatal conductance and net CO2 assimilation rate, increasing cumulative assimilation by 8-12% while maintaining their intrinsic water-use efficiency (iWUE). Under artificial fluctuating light, overexpression alleviated growth reductions relative to steady light. Under glasshouse conditions, total biomass increased by 34-44%, accompanied by greater tiller number, root biomass, bleeding sap rate, and leaf nitrogen content. Taken together, these results indicate that OsPATROL1 overexpression accelerates stomatal opening, enhances photosynthetic induction and daytime carbon gain without compromising iWUE, and is associated with greater growth.

plant biology↗

bioRxiv2025

NPF4.6-mediated ABA transport modulates stomatal responses to fluctuating light

Stomatal responses to fluctuating light (FL) strongly influence photosynthetic efficiency and biomass accumulation in seed plants. The abscisic acid (ABA) transporter NPF4.6 (also known as NRT1.2 or AIT1) mediates hormone import into guard cells, but its physiological roles in leaves remain unclear. Here, we examined the functions of NPF4.6 in Arabidopsis thaliana by characterizing two independent loss-of-function mutants (npf4.6) under both steady and FL conditions. Compared with wild type, npf4.6 showed a 21-43% reduction in the half-time of stomatal opening and a 26-32% increase in the mean net CO2 assimilation rate under simulated field light conditions, resulting in a 41-48% increase in shoot biomass. In contrast, no marked differences in photosynthetic efficiency were observed between the wild type and npf4.6 under drought stress, suggesting that the role of NPF4.6 is more pronounced under well-watered, dynamic-light conditions. Overall, these findings demonstrate that NPF4.6 contributes to the fine-tuning of stomatal kinetics under variable light environments, and highlight hormone transport as a promising target for improving photosynthesis and growth in the field.

plant biology↗

bioRxiv2025

Root Water Uptake and Photosynthesis Synergistically Enhance Drought Tolerance in Interspecific Hybrid Sugarcane

Sugarcane (Saccharum spp. hybrids) is a globally important crop for food and bioenergy, but its production is increasingly threatened by drought driven by climate change. Drought causes complex interactions between root function and leaf photosynthesis, but their underlying mechanisms remain largely unstudied in sugarcane. To address this knowledge gap, we grew up to eight sugarcane cultivars in one field and two pot experiments inside a rain-out shelter. The relative growth rate of these eight cultivars under both well-watered and water-limited conditions was largely explained by net assimilation rate, which depended on bleeding sap rate caused by root pressure. Among the cultivars, Harunoogi--a first-generation backcross cultivar between a wild relative (S. spontaneum) and a commercial cultivar--exhibited improved drought avoidance through adequate root water supply, whereas the commercial cultivar NiTn18 showed the opposite. Throughout the drought and recovery, Harunoogi exhibited significantly higher leaf area, stomatal conductance, chlorophyll content, and maximum amplitude of the reaction center chlorophyll of PSI than cultivar NiTn18, which resulted in a higher net photosynthetic rate and biomass. These results highlight the potential of improving both root function and photosynthesis as an effective approach to developing drought-tolerant sugarcane. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=93 SRC="FIGDIR/small/662668v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@133d4eforg.highwire.dtl.DTLVardef@1e0ac0borg.highwire.dtl.DTLVardef@13f0b3dorg.highwire.dtl.DTLVardef@1fb1208_HPS_FORMAT_FIGEXP M_FIG C_FIG

plant biology↗

bioRxiv2024

PATROL1-mediated H+-ATPase translocation boosts plant growth under drought by optimizing root and leaf functions

Optimizing leaf photosynthesis and root water and mineral uptake in crops during drought is crucial for enhancing agricultural productivity under climate change. Although plasma membrane H+-ATPase plays a key role in plant physiological processes, its overexpression alone does not consistently improve growth. While PROTON ATPASE TRANSLOCATION CONTROL 1 (PATROL1) regulates H+-ATPase translocation in response to various environmental stimuli in leaves, its function in roots remains largely unknown. Here we show that H+-ATPase was coimmunoprecipitated with PATROL1 in roots of Arabidopsis thaliana. Micrografting between wild type and PATROL1 knockout or overexpression lines showed that PATROL1 are indispensable in both shoots and roots, indicating that root uptake and leaf photosynthesis are simultaneous limiting factors for plant growth under drought conditions. PATROL1 overexpression in whole plants resulted in a 41% increase above wild type in shoot dry weight under drought conditions. These findings highlight the potential of H+-ATPase regulation in roots as a new strategy to improve plant productivity, particularly under drought conditions.

plant biology↗