Graphene Quantum Dots (GQD)-Mediated dsRNA Delivery for the Control of Fusarium Head Blight Disease in Wheat

Graphene quantum dots (GQDs), a class of fluorescent carbon materials, have displayed significant potential in various fields such as energy devices, catalysis, sensing, bioimaging, and drug delivery. Because of their extremely small size, generally less than 100 nm, they also have tremendous potential in plant science research, especially for the delivery of nucleic acids, breaking the barrier of cell walls. In this study, we synthesized GQDs with a size range of 2-5 nm, characterized them, and surface-functionalized them with branched polyethylenimine (bPEI). We then used the surface-functionalized GQDs as carriers to deliver double-stranded RNA (dsRNA) that target two growth-and-development-related genes in Fusarium graminearum─the causative organism of the Fusarium head blight disease of wheat. The successful binding of dsRNA to GQDs-bPEIs was demonstrated through gel-shifting assays, showcasing the potential for efficient dsRNA delivery. We designed dsRNAs targeting the MGV1 and RAS1 genes of F. graminearum by using the pssRNAit pipeline, ensuring high specificity and no off-target effects. The coding sequences of the designed dsRAS1 and dsMGV1 were cloned into the L4440 vector and transformed into the Escherichia coli HT115 strain for dsRNA production. Fungal culture analysis revealed that the inclusion of dsRNAs in potato dextrose agar (PDA) media effectively slowed down the growth. Exogenous spraying experiments both in plate cultures and in intact wheat spikes demonstrated that the dsRNA:GQDs-bPEIs treatment was more effective in restricting fungal mycelium growth or the number of infected spikelets compared to naked dsRNA treatment. Our study demonstrates the promising potential of graphene quantum dots as carriers for dsRNA-based fungal disease management in wheat and other crops.

Methods to Determine the Role of Autophagy Proteins in C. elegans Aging

This chapter describes methods for the analysis of autophagy proteins in C. elegans aging. We discuss the strains to be considered, the methods for the delivery of double-stranded RNA, and the methods to measure autophagy levels, autophagic flux, and degradation by autophagy.

Feeding the germline

This outlook highlights the accompanying paper by Chi et al. on a nucleotide nutrient-sensing pathway to regulate germline proliferation in C. elegans.

Nucleotides are required in order to replicate DNA in the developing germline. Here, Chi and colleagues (pp. 307–320) have used Caernohabditis elegans to identify a GLP-1-dependent checkpoint that senses food (bacterially)-supplied nucleotide levels, arresting reproductive development in the absence of sufficient nucleotide supplies.

Nucleotide levels regulate germline proliferation through modulating GLP-1/Notch signaling in C. elegans

In this study, Chi et al. researched the link between known nutrient-sensing systems and reproductive programs. Using a model system in C. elegans, they show that a Notch signaling pathway senses the level of uridine/thymidine and controls germline proliferation, delineating a previously unknown nucleotide-sensing mechanism for controlling reproductivity.

Animals alter their reproductive programs to accommodate changes in nutrient availability, yet the connections between known nutrient-sensing systems and reproductive programs are underexplored, and whether there is a mechanism that senses nucleotide levels to coordinate germline proliferation is unknown. We established a model system in which nucleotide metabolism is perturbed in both the nematode Caenorhabditis elegans (cytidine deaminases) and its food (Escherichia coli); when fed food with a low uridine/thymidine (U/T) level, germline proliferation is arrested. We provide evidence that this impact of U/T level on the germline is critically mediated by GLP-1/Notch and MPK-1/MAPK, known to regulate germline mitotic proliferation. This germline defect is suppressed by hyperactivation of glp-1 or disruption of genes downstream from glp-1 to promote meiosis but not by activation of the IIS or TORC1 pathways. Moreover, GLP-1 expression is post-transcriptionally modulated by U/T levels. Our results reveal a previously unknown nucleotide-sensing mechanism for controlling reproductivity.

The SKN-1 hunger games: May the odds be ever in your favor

Animals must continually assess nutrient availability to develop appropriate strategies for survival and reproductive success. It is no secret that nutritional state plays a large role in both aging and health.(1-7) Appropriate cellular energy usage is not only crucial for animal starvation survival, but is also important for diseases such as obesity and cancer, which characteristically have metabolic dysfunction.(8-10) C. elegans are exceptionally well poised to handle bouts of starvation as resource availability in the wild varies greatly.(11,12) We recently discovered an evolutionarily conserved pathway, regulated by the cytoprotective transcription factor SKN-1/Nrf2, which integrates diet composition and availability with utilization for survival.(13,14) These responses have potent impact on organismal physiology and remarkably are influenced by current and parental life history events, including choice of diet. In this commentary we will focus on recent insights concerning dietary intake and the impact that this can have throughout the life history of the nematode, Caenorhabditis elegans. In light of the strong impact that diet plays throughout life we urge caution when interpreting previous studies that make use of only one diet and suggest a reinvestigation utilizing a different diet is warranted.