Biology subjects

Li, M.-J.

Publications and source records attributed to Li, M.-J..

5 recordsLinked to original sources

bioRxiv2026

RbohF-mediated ROS production is required for tapetal PCD and pollen maturation in rice

Reactive oxygen species (ROS) function as critical signaling molecules during plant reproductive development, particularly in regulating tapetal programmed cell death (PCD). However, the molecular mechanisms controlling ROS production in rice anthers remain incompletely understood. In this study, we characterized the role of RbohF, a rice respiratory burst oxidase homolog, using CRISPR/Cas9 knockout lines. Loss of RbohF resulted in severe defects in anther development, including impaired pollen maturation and reduced fertility. Histological analyses revealed progressive degeneration of microspores and abnormal tapetal persistence in the mutant. ROS staining demonstrated that superoxide and hydrogen peroxide accumulation was significantly reduced and delayed in rbohf anthers, particularly at the young microspore stage. Consistently, TUNEL assays showed delayed tapetal PCD in the mutant, indicating that RbohF-mediated ROS production is required for the timely initiation of tapetal degeneration. Gene expression analyses further suggested that RbohF functions downstream of major transcriptional regulators of pollen development. Notably, the male-sterile phenotype of rbohf mutants was exacerbated at cooler temperatures, highlighting a role for RbohF in buffering environmental stress. Together, these findings establish RbohF as a key regulator of ROS homeostasis, integrating developmental and environmental signals to ensure proper pollen development in rice.

developmental biology↗

bioRxiv2026

Root Hydraulic and Metabolic Regulation Drives Drought Tolerance in Napier Grass

Napier grass (Cenchrus purpureus syn. Pennisetum purpureum), a perennial C4 forage and bioenergy crop, exhibits strong drought resilience, yet the integrative mechanisms underlying this tolerance remain incompletely understood. This study examined physiological, hydraulic, and metabolic responses of four Napier grass cultivars under PEG-induced osmotic stress and progressive soil water deficit. Drought significantly increased the root-to-shoot ratio, indicating preferential biomass allocation to roots, which supported maintenance of shoot growth and tissue water status. All cultivars showed an approximate twofold increase in water-use efficiency (WUE) under water deficit, with cv2 and cv7 displaying superior performance. Upregulation of aquaporin genes (PIP2;2 and PIP2;3) suggested active hydraulic regulation that sustained carbon assimilation under reduced transpiration. Metabolic profiling revealed pronounced root-centered osmotic adjustment, including accumulation of galactinol, myo-inositol, raffinose family oligosaccharides, proline, and several amino acids. Enhanced expression of the galactinol synthase gene confirmed activation of raffinose biosynthesis pathways. Genotypic variation highlighted cv2 as particularly drought resilient. Rapid post-stress regrowth further underscored the importance of perennial root persistence. In conclusion, drought tolerance in Napier grass arises from coordinated hydraulic resilience, osmotic adjustment, and C4 photosynthetic efficiency, supporting its suitability for forage and bioenergy production in water-limited environments. SignificantThis study shows drought tolerance in Napier grass relies on root-driven hydraulic and metabolic regulation with efficient water-use efficiency, rather than avoidance, and that PEG responses predict field performance.

plant biology↗

bioRxiv2024

Uncovering Ancient DNA in Petroleum: Insights into Earth Hidden Life Events and Geological History

Specific macromolecules in petroleum, preserved through geological processes from ancient organisms, are recognized as molecular fossils or geochemical markers (GMs). Our selected GMs indicate that the source rocks of Nanyang Oilfield formed in an anoxic, saline, and stratified lacustrine environment with marine influence. Contrary to science fiction notions that oil originates from ancient large animals, mainstream academia has consistently asserted that oil is derived from the organic matter of lower life forms, formed over extended geological processes, with intact DNA no longer persisting in oil post-formation. However, this study successfully extracted 3,159,020 DNA fragments from the petroleum samples using the nanoparticle affinity bead technology, followed by sequencing and classification via the mega screen method. These fragments, categorized as original in situ DNA (oriDNA), recent environmental DNA (preDNA), and paleo-environmental DNA (paeDNA), exhibit a "Genome Accumulated over Time" (GAT) pattern of "old-less, new-many". This aligns with findings from GMs while offering more specific genetic information. The analysis reveals evidence of historical events, including animal extinctions, marine invasions, ancient bird species presence, Asian Homo erectus activities, and modern human influences in preDNA. Notably, the mitogenomic data positions Asian Homo erectus closer to modern humans than to chimpanzees at the maternal basis. The absence of deamination in petroleum ancient DNA (aDNA) fragments is likely due to the anaerobic, anhydrous environment and the screening process that excludes degraded fragments. Consequently, the authenticity criteria and scope of application of traditional aDNA methods require reevaluation. Surprisingly, the near-absence of oriDNA has impeded our efforts to determine the specific biological origins of the oil. These findings position petroleum as a novel, non-skeletal source of aDNA, offering insights into ancient animal activities, geological changes, and human origins while underscoring its potential as an untapped resource for studying genetic preservation across geological timescales.

paleontology↗

bioRxiv2020

GAMYB modulates bHLH142 and is homeostatically regulated by TDR during rice anther tapetal and pollen development

GAMYB, UDT1, TIP2/bHLH142, TDR, and EAT1/DTD are important transcription factors (TFs) that play a crucial role during rice pollen development. This study demonstrates that bHLH142 acts downstream of UDT1 and GAMYB and works as a "hub" in these two pollen pathways. We show that GAMYB modulates bHLH142 expression through specific binding to the MYB motif of bHLH142 promoter during early stage of pollen development; while TDR acts as a transcriptional repressor of the GAMYB modulation of bHLH142 by binding to the E-box close to the MYB motif on the promoter. The up- and down-regulation of TFs highlights the importance that a tight, precise, and coordinated regulation among these TFs is essential for normal pollen development. Most notably, this study illustrates the regulatory pathways of GAMYB and UDT1 that rely on bHLH142 in a direct and an indirect manner, respectively, and function in different tissues with distinct biological functions during pollen development. This study advances our understanding of the molecular mechanisms of rice pollen development. HighlightGAMYB can directly modulate the transactivation of the bHLH142, but the modulation is repressed by TDR to keep the homeostasis of bHLH142 gene expression to ensure normal pollen development.

molecular biology↗

bioRxiv2017

Molecular Basis Underlying Male Sterility In bHLH142 Overexpressing Rice

Development of stable male sterility lines is essential for efficient hybrid seed production. We previously showed that knockout of bHLH142 in rice (Oryza sativa) causes pollen sterility by interrupting tapetal programmed cell death (PCD). In this study, we demonstrated that overexpression of bHLH142 (OE142) under the control of ubiquitin promoter also leads to male sterility in rice by triggering the premature onset of PCD. Protein of bHLH142 was found to accumulate specifically in the OE142 anthers. Overexpression of bHLH142 induced early expression of several key regulatory transcription factors in pollen development. In particular, the upregulation of EAT1 at the early stage of pollen development promoted premature PCD in the OE142 anthers, while its downregulation at the late stage impaired pollen development by suppressing genes involved in pollen wall biosynthesis, ROS scavenging and PCD. Collectively, these events led to male sterility in OE142. Analyses of related mutants further revealed the hierarchy of these pollen development regulatory genes. Thus, the findings of this study create a new method to generate genic male sterility in rice. Exploitation of this novel functionality of bHLH142 would confer a big advantage to hybrid seed production.\n\nHighlightOverexpression of bHLH142 leads to male sterility in transgenic rice due to early onset of tapetal PCD. This study creates a new method to generate male sterility in rice.

molecular biology↗