Lipid droplet functions beyond energy storage.

The Para rubber tree (Hevea brasiliensis) is an economically important tropical tree species that produces natural rubber, an essential industrial raw material. Here we present a high-quality genome assembly of this species (1.37 Gb, scaffold N50 = 1.28 Mb) that covers 93.8% of the genome (1.47 Gb) and harbours 43,792 predicted protein-coding genes. A striking expansion of the REF/SRPP (rubber elongation factor/small rubber particle protein) gene family and its divergence into several laticifer-specific isoforms seem crucial for rubber biosynthesis. The REF/SRPP family has isoforms with sizes similar to or larger than SRPP1 (204 amino acids) in 17 other plants examined, but no isoforms with similar sizes to REF1 (138 amino acids), the predominant molecular variant. A pivotal point in Hevea evolution was the emergence of REF1, which is located on the surface of large rubber particles that account for 93% of rubber in the latex (despite constituting only 6% of total rubber particles, large and small). The stringent control of ethylene synthesis under active ethylene signalling and response in laticifers resolves a longstanding mystery of ethylene stimulation in rubber production. Our study, which includes the re-sequencing of five other Hevea cultivars and extensive RNA-seq data, provides a valuable resource for functional genomics and tools for breeding elite Hevea cultivars. A high-quality rubber tree genome reveals insights into the evolution of rubber biosynthesis and ethylene stimulation in rubber production. Together with transcriptome data, this study provides valuable data for the research and breeding of rubber trees.

/pdf/the-rubber-tree-genome-reveals-new-insights-into-rubber-2e26e75fb8.pdf

The rubber tree genome reveals new insights into rubber production and species adaptation

Supporting food systems transformation : The what, why, who, where and how of mission-oriented agricultural innovation systems

Eukaryotic cells compartmentalize neutral lipids into organelles called lipid droplets (LDs), and while much is known about the role of LDs in storing triacylglycerols in seeds, their biogenesis and function in nonseed tissues are poorly understood. Recently, we identified a class of plant-specific, lipid droplet-associated proteins (LDAPs) that are abundant components of LDs in nonseed cell types. Here, we characterized the three LDAPs in Arabidopsis (Arabidopsis thaliana) to gain insight to their targeting, assembly, and influence on LD function and dynamics. While all three LDAPs targeted specifically to the LD surface, truncation analysis of LDAP3 revealed that essentially the entire protein was required for LD localization. The association of LDAP3 with LDs was detergent sensitive, but the protein bound with similar affinity to synthetic liposomes of various phospholipid compositions, suggesting that other factors contributed to targeting specificity. Investigation of LD dynamics in leaves revealed that LD abundance was modulated during the diurnal cycle, and characterization of LDAP misexpression mutants indicated that all three LDAPs were important for this process. LD abundance was increased significantly during abiotic stress, and characterization of mutant lines revealed that LDAP1 and LDAP3 were required for the proper induction of LDs during heat and cold temperature stress, respectively. Furthermore, LDAP1 was required for proper neutral lipid compartmentalization and triacylglycerol degradation during postgerminative growth. Taken together, these studies reveal that LDAPs are required for the maintenance and regulation of LDs in plant cells and perform nonredundant functions in various physiological contexts, including stress response and postgerminative growth.

Lipid Droplet-Associated Proteins (LDAPs) Are Required for the Dynamic Regulation of Neutral Lipid Compartmentation in Plant Cells.

Turning Over a New Leaf in Lipid Droplet Biology

Innovation types in the bioeconomy

Industries across the world are making a transition from fossil resources to renewable biological feedstock for the production of chemicals, fuels, and materials, as a strategy to promote sustainable development and economic growth. However, limited biomass availability can halt the expansion of bio-based sectors, unless alternative raw materials are employed and cascading uses are implemented on a large scale. Key Enabling Technologies (KETs) can contribute to feedstock diversification and improved biomass conversion efficiencies along supply chains, although concerns arise about their actual viability and competitiveness. A systematic review of Life Cycle Assessments (LCAs) and related process-based approaches is carried out to evaluate the sustainability of advanced bio-based technologies, defined as those that use either non-food feedstock or circularity principles –or both– for delivering diverse products. A classification scheme is proposed to categorise KETs based on the feedstock employed (plant residues and perennials, designer crops, algae, or biological waste) or the underlying technological configuration (enzyme/microbial assisted processing or biorefineries). Results show that producing biofuels and biochemicals from perennial plants, lignocellulosic residues and algae has advantages in terms of greenhouse gas emissions relative to their fossil counterparts, while trade-offs occur with other environmental impacts and sustainability dimensions. Cradle-to-cradle systems can deliver additional sustainability gains, but their implementation poses technical and socio-political challenges. Further harmonisation of LCA methodologies is desirable to compare KETs in different sectoral, geographical and policy contexts. In spite of the diversity of outcomes and approaches, this review provides an overview of advanced bio-based technologies, while shedding light on the often overestimated sustainability benefits of the bioeconomy.

Sustainability check for bio-based technologies: A review of process-based and life cycle approaches

The diversification of food crops can improve our diets and address the effects of climate change, and in this context the orphan crop Chinese yam shows significant potential as a functional food. As the effects of climate change become increasingly visible even in temperate regions, there is an urgent need to diversify our crops in order to address hunger and malnutrition. This has led to the re-evaluation of neglected species such as Chinese yam (Dioscorea polystachya Turcz.), which has been cultivated for centuries in East Asia as a food crop and as a widely-used ingredient in traditional Chinese medicine. The tubers are rich in nutrients, but also contain bioactive metabolites such as resistant starches, steroidal sapogenins (like diosgenin), the storage protein dioscorin, and mucilage polysaccharides. These health-promoting products can help to prevent cardiovascular disease, diabetes, and disorders of the gut microbiome.
Whereas most edible yams are tropical species, Chinese yam could be cultivated widely in Europe and other temperate regions to take advantage of its nutritional and bioactive properties. However, this is a laborious process and agronomic knowledge is fragmented. The underground tubers contain most of the starch, but are vulnerable to breaking and thus difficult to harvest. Breeding to improve tuber shape is complex given the dioecious nature of the species, the mostly vegetative reproduction via bulbils, and the presence of more than 100 chromosomes. Protocols have yet to be established for in vitro cultivation and genetic transformation, which limits the scope of research. This article summarizes the sparse research landscape and evaluates the nutritional and medical applications of Chinese yam. By highlighting the potential of Chinese yam tubers, we aim to encourage the adoption of this orphan crop as a novel functional food.

/pdf/an-underutilized-orphan-tuber-crop-chinese-yam-a-review-442k9o58ql.pdf

An underutilized orphan tuber crop—Chinese yam : a review

Exploring the future of the bioeconomy: An expert-based scoping study examining key enabling technology fields with potential to foster the transition toward a bio-based economy

Summary
Two protein families required for rubber biosynthesis in Taraxacum brevicorniculatum have recently been characterized, namely the cis-prenyltransferases (TbCPTs) and the small rubber particle proteins (TbSRPPs). The latter were shown to be the most abundant proteins on rubber particles, where rubber biosynthesis takes place. Here we identified a protein designated T. brevicorniculatum rubber elongation factor (TbREF) by using mass spectrometry to analyze rubber particle proteins. TbREF is homologous to the TbSRPPs but has a molecular mass that is atypical for the family. The promoter was shown to be active in laticifers, and the protein itself was localized on the rubber particle surface. In TbREF-silenced plants generated by RNA interference, the rubber content was significantly reduced, correlating with lower TbCPT protein levels and less TbCPT activity in the latex. However, the molecular mass of the rubber was not affected by TbREF silencing. The colloidal stability of rubber particles isolated from TbREF-silenced plants was also unchanged. This was not surprising because TbREF depletion did not affect the abundance of TbSRPPs, which are required for rubber particle stability. Our findings suggest that TbREF is an important component of the rubber biosynthesis machinery in T. brevicorniculatum, and may play a role in rubber particle biogenesis and influence rubber production.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/tpj.12836

Identification of a Taraxacum brevicorniculatum rubber elongation factor protein that is localized on rubber particles and promotes rubber biosynthesis.

Natalie Laibach

Papers

Innovation types in the bioeconomy

Sustainability check for bio-based technologies: A review of process-based and life cycle approaches

An underutilized orphan tuber crop—Chinese yam : a review

Exploring the future of the bioeconomy: An expert-based scoping study examining key enabling technology fields with potential to foster the transition toward a bio-based economy

Identification of a Taraxacum brevicorniculatum rubber elongation factor protein that is localized on rubber particles and promotes rubber biosynthesis.