Biology subjects

Suzuki, D.

Publications and source records attributed to Suzuki, D..

3 recordsLinked to original sources

bioRxiv2026

Rice blast fungus hijacks a rice RALF peptide to initiate infection

Plant-derived peptides regulate immunity and host-microbe interactions, but whether fungal pathogens exploit endogenous plant peptides for infection-site selection remains largely unknown. Rapid alkalinization factors (RALFs) are a family of plant peptide hormones that contribute to plant development, reproduction, stress responses, and cell-wall organization. Here, we show that OsRALF7, which is an immune-activating peptide in rice (Oryza sativa), is co-opted by the rice blast fungus Magnaporthe oryzae as a host-derived cue for appressorium formation, specialized infection structures required for host penetration. While synthetic OsRALF7 peptide induced defense responses in rice suspension cells, the same peptide induced appressorium formation in M. oryzae. OsRALF7-induced appressorium formation was associated with activation of the cAMP/PKA and Pmk1 MAPK pathways and required a hydrophobic surface. M. oryzae inoculated onto Osralf7 knockout plants formed fewer appressoria, and the positioning of these appressoria relative to the boundaries between two adjacent plant epidermal cells was altered. These findings suggest that OsRALF7 provides positional information for infection initiation for M. oryzae. OsRALF7 localized to the plasma membrane and cell wall in rice, and its appressorium-inducing activity required a conserved YISY motif and cysteine residues. This activity was not conserved in Colletotrichum higginsianum, as RALF23 from Arabidopsis thaliana did not induce appressorium formation but instead showed antifungal activity. Together, these findings uncover a dual function of endogenous plant immune-modulating RALF peptides at the plant-pathogen interface, where they can be exploited by M. oryzae as a host-derived cue for infection initiation while also retaining antifungal activity against other fungal species.

plant biology↗

bioRxiv2026

Hypothermic Conditions Impair GnRH Pulse Generator Activity and Gametogenesis

Mammalian reproductive function is driven by arcuate kisspeptin neurons, pacemakers of gonadotropin secretion. During energy shortages, animals reallocate resources from reproduction to survival; however, the underlying neural mechanisms remain elusive. Here we used fiber photometry to chronically monitor synchronized episodes of arcuate kisspeptin neuron activity (SEskiss) in adult mice under various energy-saving conditions. In both sexes, SEskiss frequency was markedly suppressed during fasting-induced torpor and pharmacologically induced hypothermia, whereas hypometabolism alone had no discernible effect. A Q neuron-induced hypothermic state (QIH) robustly suppressed SEskiss, leading to impaired gamete maturation, whereas warming the body temperature during QIH fully restored SEskiss frequency. These findings demonstrate that hypothermia, rather than hypometabolism, is the primary driver of suppression of the hypothalamic reproductive axis during energy-saving conditions. This study provides insights into how thermal signals act as critical gatekeepers in the mammalian reproductive system.

neuroscience↗

bioRxiv2025

Evaluation of Conditional Treatment Effect of Salt Stress on Tomato Sugar Content Using Causal Machine Learning: A Pilot Study

Exposing tomatoes to salt stress has been reported to increase the fruit sugar content ({degrees}Brix); however, this treatments causal impact under varying environmental conditions remains unclear. In this pilot study, a causal inference analysis was conducted using a Causal Tree to analyze the factors that influence the effect of salt-stress treatment on improving the {degrees}Brix in tomatoes. Data were collected from a single greenhouse using one cultivar over multiple cultivation periods, totaling 707 fruits. Propensity score matching was applied to reduce the covariate imbalance between the salt (NaCl) treatment and control groups. Using a Causal Tree, conditional average treatment effects were then estimated to assess heterogeneity in treatment impact based on environmental variables, such as temperature, humidity, and illumination. Treatment with NaCl significantly increased {degrees}Brix compared to the control, but the magnitude of the effect varied depending on the environmental conditions. The Causal Tree analysis based on the accumulated cultivation data identified specific combinations of environmental factors under which the impact of NaCl treatment on {degrees}Brix enhancement was more pronounced. For example, the estimated Conditional Average Treatment Effect (CATE) reached as high as 0.88 when humidity was [≥]75%, illuminance was [≥]8144 lx, and categorical variable C3 was F1 or F2. In contrast, the CATE dropped to as low as 0.036 under low humidity (<79%) and high temperature (<24{degrees}C). These findings highlight humidity as the most influential factor, whose impact was modulated by interactions with temperature and light conditions.

plant biology↗