Decoding the initial chemical signals in plant-cyanobacteria symbiosis
Ente: Cell, Dev, & Physio
Scadenza: 2029-08-31
Importo max: 842.960 EUR
Paese: US
Descrizione
Nitrogen is essential for plant growth and is often the nutrient that limits agricultural productivity. To meet global food demand, more than 100 million tons of synthetic nitrogen fertilizer are applied each year, which not only generates greenhouse gases, but also drives nutrient runoff and harmful algal blooms. A more sustainable alternative is biological nitrogen fixation, in which certain microbes convert inert atmospheric nitrogen into a usable form. While the partnership between legumes and nitrogen-fixing rhizobial bacteria is well known, another group of nitrogen-fixing partners—cyanobacteria—has been largely overlooked. Cyanobacteria are especially promising for future crop engineering because they have independently formed symbioses with many unrelated plant lineages, from hornworts and liverworts to ferns, cycads, and the flowering plant Gunnera, suggesting broad host compatibility. Yet how these partnerships begin remains almost entirely unknown. Plants initiate the relationship by secreting a chemical signal that prepares cyanobacteria for symbiosis, but the identity of this signal has never been determined. This project seeks to decode that first chemical message. In doing so, it advances fundamental understanding of how complex biological partnerships arise and lays the groundwork for eventually engineering crops to host their own nitrogen-fixing partners—reducing dependence on synthetic fertilizer and supporting a more sustainable bioeconomy. The project also broadens training by mentoring undergraduate, graduate, and postdoctoral researchers, integrating its findings into an intensive course on symbiosis, and engaging the public through a widely followed science-communication platform.
The long-term goal of this research is to uncover the chemical signals and genes that enable plants to form symbioses with nitrogen-fixing cyanobacteria. The project focuses on the hormogonia-inducing factor (HIF), the first signal plants secrete to initiate the partnership. Using the hornwort Anthoceros punctatus as a genetically tractable model, the team has shown that hornworts secrete a novel, structurally uncharacterized diterpenoid that functions as HIF, and identified a candidate biosynthetic gene cluster induced under nitrogen starvation. Aim 1 will establish the precise structure of the diterpenoid by purifying it from scaled-up cultures and analyzing it by NMR spectroscopy. Aim 2 will functionally characterize the biosynthetic gene cluster through heterologous expression in Escherichia coli, yeast, and Nicotiana benthamiana, complemented by CRISPR-Cas9 knockouts in Anthoceros. Aim 3 will test whether similar signaling molecules were convergently recruited across the plant tree of life using comparative metabolomics in the liverwort Blasia pusilla and the flowering plant Gunnera perpensa. By uncovering the identity and biosynthesis of the symbiotic signal, the results of this work could provide the toolkit needed to control cyanobacter
Istituzione: Duke University
Sede: DURHAM, NC
PI: Fay-Wei Li
Settori: Biological Sciences
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