June 2024 Research Highlights

Deciphering the roles of cyanobacteria Δ9 desaturases

Editor’s Choice – Free Access!

Filamentous cyanobacteria desaturases (of which there are four main types, including DesC), desaturate fatty acids esterified to acyl glycerolipids. The Nostocales are known to have two DesC Δ9 desaturases, however, the role of DesC2 has been somewhat unclear to date. Effendi et al. have now found that DesC2 uniquely desaturates fatty acids at the sn-2 position of glycerolipids but cannot complement the function of DesC1, which desaturates fatty acids at the sn-1 position. Moreover, they found that this enzyme is essential in filamentous cyanobacteria, in turn revealing an essential physiological function for unsaturated fatty acids at position sn-2 of glycerolipids in the Nostocales. This paper forms part of the special issue on Plant and Algal Lipids, see editorial by Li-Beisson and Roston.

First Author Spotlight: Devi Bentia Effendi obtained his Ph.D. in 2022 under the supervision of Prof. Koichiro Awai at the Shizuoka University, Japan, where he studied the adaptation mechanisms of cyanobacteria, with a focus on lipid and sugar metabolism, to harsh environments. His current research as a staff researcher at the National Research and Innovation Agency, Indonesia, focuses on identification and utilization of indigenous microalgae and cyanobacteria, which are suitable for production of biohydrogen, biodiesel, and secondary metabolites. Outside of academia, Devi enjoys traveling and exploring culinary delights. 

An esterase/lipase controls hull attachment in barley

The barley grain is encased in a tightly adherent hull, but sometimes the hull can partially shed in a process known as grain ‘skinning’, which negatively impacts grain quality. Campoli et al. have shown that the fruit pericarp cuticle of the grain influences hull adhesion and that, specifically, the esterase/lipase-encoding HvGDSL1 gene - that was previously shown to be necessary for intact and glaucous vegetative tissue cuticles - is also required for strong hull adherence. These findings identify a shared genetic basis for cuticular specialisation across different barley organs. This paper forms part of the special issue on Plant and Algal Lipids (see editorial by Li-Beisson and Roston). 

First-Author Spotlight: Chiara Campoli is originally from Italy and has worked on different aspects of barley genetics and development throughout her career. She obtained her Ph.D. from the University of Verona, where she studied chloroplast development. This was followed by a postdoc at the Max Planck Institute for Plant Breeding Research, Germany, where she worked on flowering time before she moved to the University of Dundee, Scotland (UK), where she developed her research interests in plant cuticles and waxes. Chiara is now an independent group leader at the James Hutton Institute, where she explores how cuticles help plants adapt to environmental changes and, ultimately, how we can leverage this knowledge for sustainable crop production. 

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Linking photosynthesis-associated gene expression with galactolipid biosynthesis

Thylakoids are composed of photosynthetic proteins and membrane lipids (predominantly galactolipids) - both of which appear to be coordinately regulated. Fujii et al. sought to investigate the basis for this association by assessing gene expression patterns in galactolipid-deficient Arabidopsis seedlings during the de-etiolation process. They found that galactolipid synthesis is essential for plastid gene expression and is involved in regulating nuclear gene expression via retrograde signaling, thereby optimizing the abundance of photosynthetic proteins. These findings highlight the critical contribution of lipids to the construction of the photosynthetic apparatus and chloroplast development. This paper forms part of the special issue on Plant and Algal Lipids, see editorial by Li-Beisson and Roston.

First-Author Spotlight: Sho Fujii is an assistant professor at Hirosaki University, Japan. He received his Ph.D. from the University of Tokyo in 2019, under the supervision of Professor Hajime Wada. Sho’s research focuses on the regulatory mechanism of chloroplast differentiation in land plants. Recently, he has been particularly interested in plastid gene expression and its relationship with thylakoid biogenesis. Since becoming a principal investigator in 2022, he has endeavored to create a comfortable and productive research environment. Sho enjoys music, traveling, cooking, and eating.

Shuffling the deck for cyanobacteria nitrogen-fixation genes

Recombination via simple site-specific excision events occurs in the genomes of heterocyst-forming cyanobacteria to restore the complete coding regions of nitrogenase subunits that are required for nitrogen fixation. Uesaka and Banba et al. have now demonstrated that the four nifBHDK genes essential for nitrogen fixation are fragmented into 13 parts across the genome of Calothrix sp. NIES-4101 and are restored upon heterocyst differentiation in the cyanobacterium. The genome reorganization includes site-specific inversion events and is the most complex case reported so far in cyanobacteria. See also Commentary by Jimbo, in this issue.

Co-First Authors Spotlight:

Kazuma Uesaka is a researcher in Professor Yuichi Fujita’s Group at Nagoya University, Japan. He is an expert in bioinformatics, especially in analyzing next generation sequencing data, focusing on cyanobacteria and other microorganisms. Kazuma is particularly interested in cyanobacterial nitrogen fixation; while performing a comparative genome analysis to determine the nitrogen-fixing ability of cyanobacteria, he found that Calothrix sp. NIES-4101 has highly fragmented nif genes, which led to the study featured in this paper. In his spare time, Kazuma is a blogger for bioinformatics tools (https://kazumaxneo.hatenablog.com/) and he also enjoys climbing mountains at weekends.

 Mari Banba is a postdoc in Professor Yuichi Fujita’s Group at Nagoya University. Her research focuses on nitrogen fixation mechanisms in oxygenic photosynthetic organisms (cyanobacteria). She is broadly interested in how nitrogen fixation -the oxygen-vulnerable reaction that was created during early evolution of life under anaerobic environments-, operates in the current oxygen-rich world. Mari hopes that basic research into this question will help improve future agricultural productivity. Outside of the lab, balancing between work and life is her daily challenge.