A conserved amino acid residue critical for product and substrate specificity in plant triterpene synthases

Triterpenes are structurally complex plant natural products with numerous medicinal applications. They are synthesized through an origami-like process that involves cyclization of the linear 30 carbon precursor 2,3-oxidosqualene into different triterpene scaffolds. Here, through a forward genetic screen in planta, we identify a conserved amino acid residue that determines product specificity in triterpene synthases from diverse plant species. Mutation of this residue results in a major change in triterpene cyclization, with production of tetracyclic rather than pentacyclic products. The mutated enzymes also use the more highly oxygenated substrate dioxidosqualene in preference to 2,3-oxidosqualene when expressed in yeast. Our discoveries provide new insights into triterpene cyclization, revealing hidden functional diversity within triterpene synthases. They further open up opportunities to engineer novel oxygenated triterpene scaffolds by manipulating the precursor supply

The Global Garden project: Imagining plant science

Plants are rich sources of drugs and other high-value chemicals that are used by humans. Many of the plant species that produce important molecules grow in remote locations and have extensive histories of indigenous use. Global concerns about sustainable supply have in some cases led to the development of alternative methods for production using biotechnological approaches. Consideration of responsible stewardship and use of the world's plants and associated traditional knowledge for the greater human good are at the heart of the Convention on Biological Diversity and the recently implemented Nagoya Protocol. The development of fora that enable open discussion and exploration of issues relating to these aspects will be critical in endeavors to protect and preserve both the environment and present and future generations. Summary: Here, we investigate the application of cross-disciplinary approaches to explore societal perceptions of plants and their uses, focusing on high-value chemicals. The Global Garden project engages the public, researchers, and regulators in day-long workshops that combine science, poetry, and visual arts practice to foster participants’ skill in imagining and re-imagining relationships between high-value plant products, biotechnology, and social and ethical aspects of these. The project represents an intervention into discussions of science communications and public engagement, addressing the uses and benefits of arts-based approaches to foster imaginative engagement with plant science. The workshop reported here began with real plant case studies and a discussion of the aims of scientists using them. Participants were invited to respond to the issues of relationships among plants, chemicals, and people raised by the case studies through poetry and visual artwork. The poems and artwork that were produced show variation in the participants’ imaginings of plant science. They present distinctive visions of research and innovation and of the associated ethical and social implications. This type of forum, based on creative immersion, opens up opportunities for engaging with and exploring complex relations between plant biotechnology, society, and ethics. This article offers a reflection on the uses, challenges, and implications of arts-based approaches to research communications and public engagement that disrupts traditional knowledge transfer structures. In doing so, we frame the project within science communication pedagogies and consider public engagement a form of pedagogy

Speed breeding in growth chambers and glasshouses for crop breeding and model plant research

‘Speed breeding’ (SB) shortens the breeding cycle and accelerates crop research through rapid generation advancement. SB can be carried out in numerous ways, one of which involves extending the duration of plants’ daily exposure to light, combined with early seed harvest, to cycle quickly from seed to seed, thereby reducing the generation times for some long-day (LD) or day-neutral crops. In this protocol, we present glasshouse and growth chamber–based SB approaches with supporting data from experimentation with several crops. We describe the conditions that promote the rapid growth of bread wheat, durum wheat, barley, oat, various Brassica species, chickpea, pea, grass pea, quinoa and Brachypodium distachyon. Points of flexibility within the protocols are highlighted, including how plant density can be increased to efficiently scale up plant numbers for single-seed descent (SSD). In addition, instructions are provided on how to perform SB on a small scale in a benchtop growth cabinet, enabling optimization of parameters at a low cost

HpARI protein secreted by a helminth parasite suppresses interleukin-33

Infection by helminth parasites is associated with amelioration of allergic reactivity, but mechanistic insights into this association are lacking. Products secreted by the mouse parasite Heligmosomoides polygyrus suppress type 2 (allergic) immune responses through interference in the interleukin-33 (IL-33) pathway. Here, we identified H. polygyrus Alarmin Release Inhibitor (HpARI), an IL-33-suppressive 26-kDa protein, containing three predicted complement control protein (CCP) modules. In vivo, recombinant HpARI abrogated IL-33, group 2 innate lymphoid cell (ILC2) and eosinophilic responses to Alternaria allergen administration, and diminished eosinophilic responses to Nippostrongylus brasiliensis, increasing parasite burden. HpARI bound directly to both mouse and human IL-33 (in the cytokine's activated state) and also to nuclear DNA via its N-terminal CCP module pair (CCP1/2), tethering active IL-33 within necrotic cells, preventing its release, and forestalling initiation of type 2 allergic responses. Thus, HpARI employs a novel molecular strategy to suppress type 2 immunity in both infection and allergy. Osbourn et al identified HpARI, a protein secreted by a helminth parasite that is capable of suppressing allergic responses. HpARI binds to IL-33 (a critical inducer of allergy) and nuclear DNA, preventing the release of IL-33 from necrotic epithelial cells

Operons

Operons (clusters of co-regulated genes with related functions) are common features of bacterial genomes. More recently, functional gene clustering has been reported in eukaryotes, from yeasts to filamentous fungi, plants, and animals. Gene clusters can consist of paralogous genes that have most likely arisen by gene duplication. However, there are now many examples of eukaryotic gene clusters that contain functionally related but non-homologous genes and that represent functional gene organizations with operon-like features (physical clustering and co-regulation). These include gene clusters for use of different carbon and nitrogen sources in yeasts, for production of antibiotics, toxins, and virulence determinants in filamentous fungi, for production of defense compounds in plants, and for innate and adaptive immunity in animals (the major histocompatibility locus). The aim of this article is to review features of functional gene clusters in prokaryotes and eukaryotes and the significance of clustering for effective function

Minimum Information about a Biosynthetic Gene cluster

A wide variety of enzymatic pathways that produce specialized metabolites in bacteria, fungi and plants are known to be encoded in biosynthetic gene clusters. Information about these clusters, pathways and metabolites is currently dispersed throughout the literature, making it difficult to exploit. To facilitate consistent and systematic deposition and retrieval of data on biosynthetic gene clusters, we propose the Minimum Information about a Biosynthetic Gene cluster (MIBiG) data standard.Chemistry and Chemical Biolog

Molecular genetic analysis of pathogenicity and host range determinants in the take-all fungus,Gaeumannomyces graminis

Lecture given by Doctor Anne Osbourn, The Sainsbury Laboratory, John Innes Research Institute, Norwich, England, UK. at the Waite Campus, University of Adelaide, 7.4.1995.<br><br>The forty-first Hannaford Memorial Lecture<br><br><p>This lecture is part of the Campus Seminars and Distinguished Lecturer Series, Waite Campus, University of Adelaide, 1991 – 1997. </p> <a href="https://figshare.com/projects/Campus_Seminars_and_Distinguished_Lecturer_Series_Waite_Campus_University_of_Adelaide/17756">https://figshare.com/projects/Campus_Seminars_and_Distinguished_Lecturer_Series_Waite_Campus_University_of_Adelaide/17756</a