The structural basis of Rubisco phase separation in the pyrenoid
He et al. present the structural basis of the interactions between Rubisco and its intrinsically disordered linker protein Essential Pyrenoid Component 1 (EPYC1) in the model alga Chlamydomonas reinhardtii. They find that EPYC1 consists of five evenly spaced Rubisco-binding regions that share sequence similarity. Single-particle cryo-electron microscopy of these regions in complex with Rubisco indicates that each Rubisco holoenzyme has eight binding sites for EPYC1, one on each Rubisco small subunit. Interface mutations disrupt binding, phase separation and pyrenoid formation. Cryo-electron tomography supports a model in which EPYC1 and Rubisco form a codependent multivalent network of specific low-affinity bonds, giving the matrix liquid-like properties.
Small herbaria contribute unique biogeographic records to county, locality, and temporal scales
Marsico et al. sampled herbarium specimens of 40 plant taxa from each of eight states of the United States of America in four broad status categories: extremely rare, very rare, common native, and introduced. They gathered geographic information from specimens held by large (≥100,000 specimens) and small (<100,000 specimens) herbaria. The authors demonstrate that small herbaria contribute unique information for research. It is clear that unique contributions cannot be predicted based on herbarium size alone.
American Journal of Botany
A receptor-like protein mediates plant immune responses to herbivore-associated molecular patterns
Plants respond to biotic attack using an immune system of receptors to recognize molecules associated with danger. Steinbrenner et al. identified an immune receptor, termed inceptin receptor (INR), able to confer responses to defined inceptin peptide fragments present in caterpillar oral secretions. Like many plant immune receptors, INR is encoded only by certain plant species but can be transferred across families to confer new signaling and defense functions. While INR is only found in the genomes of cowpea, common bean, and related legumes, it confers defined elicitor responses to transgenic tobacco and suppresses the growth of attacking beet armyworm larvae.
Parasite dodder enables transfer of bidirectional systemic nitrogen signals between host plants
Dodder (Cuscuta spp., Convolvulaceae) is a genus of parasitic plants with worldwide distribution. Dodders are able to simultaneously parasitize two or more adjacent hosts, forming dodder-connected plant clusters. Nitrogen (N) deficiency is a common challenge to plants. To date, it has been unclear whether dodder transfers N-systemic signals between hosts grown in N-heterogeneous soil. Transcriptome and methylome analyses were carried out to investigate whether dodder (Cuscuta campestris) transfers N-systemic signals between N-replete and N-depleted cucumber (Cucumis sativus) hosts, and it was found that N-systemic signals from the N-deficient cucumber plants were rapidly translocated through C. campestris to the N-replete cucumber plants.
Multiple wheat genomes reveal global variation in modern breeding
Walkowiak et al. generated ten chromosome pseudomolecule and five scaffold assemblies of hexaploid wheat to explore the genomic diversity among wheat lines from global breeding programs. Comparative analysis revealed extensive structural rearrangements, introgressions from wild relatives and differences in gene content resulting from complex breeding histories aimed at improving adaptation to diverse environments, grain yield and quality, and resistance to stresses. They provide examples outlining the utility of these genomes, including a detailed multi-genome-derived nucleotide-binding leucine-rich repeat protein repertoire involved in disease resistance and the characterization of Sm16, a gene associated with insect resistance.
The barley pan-genome reveals the hidden legacy of mutation breeding
Jayakodi et al. report the construction of chromosome-scale sequence assemblies for the genotypes of 20 varieties of barley—comprising landraces, cultivars and a wild barley—that were selected as representatives of global barley diversity. They catalogued genomic presence/absence variants and explored the use of structural variants for quantitative genetic analysis through whole-genome shotgun sequencing of 300 gene bank accessions. They discovered abundant large inversion polymorphisms and analysed in detail two inversions that are frequently found in current elite barley germplasm; one is probably the product of mutation breeding and the other is tightly linked to a locus that is involved in the expansion of geographical range.
Species richness promotes ecosystem carbon storage: evidence from biodiversity-ecosystem functioning experiments
Xu et al. performed a meta-analysis by collecting data from 95 biodiversity-ecosystem functioning (BEF) studies across 60 sites to explore the effects of plant diversity on different C pools, including aboveground and belowground plant biomass, soil microbial biomass C and soil C content across different ecosystem types. The results showed that ecosystem C storage was significantly enhanced by plant diversity, with stronger effects on aboveground biomass than on soil C content. Moreover, the response magnitudes of ecosystem C storage increased with the level of species richness and experimental duration across all ecosystems. The effects of plant diversity were more pronounced in grasslands than in forests.
Proceedings of the Royal Society B: Biological Sciences
World Flora Online: Placing taxonomists at the heart of a definitive and comprehensive global resource on the world's plants
It is time to synthesize the knowledge that has been generated through more than 260 years of botanical exploration, taxonomic and, more recently, phylogenetic research throughout the world. The adoption of an updated Global Strategy for Plant Conservation (GSPC) in 2011 provided the essential impetus for the development of the World Flora Online (WFO) project. The project represents an international, coordinated effort by the botanical community to achieve GSPC Target 1, an electronic Flora of all plants. It will be a first‐ever unique and authoritative global source of information on the world's plant diversity, compiled, curated, moderated and updated by an expert and specialist‐based community (Taxonomic Expert Networks – “TENs” – covering a taxonomic group such as family or order) and actively managed by those who have compiled and contributed the data it includes
Increased growing-season productivity drives earlier autumn leaf senescence in temperate trees
The length of the growing season in temperate forests has been increasing under recent climate change because of earlier leaf emergence and later leaf senescence. However, Zani et al. show that this trend might be reversed as increasing photosynthetic productivity begins to drive earlier autumn leaf senescence. Using a combination of experimental, observational, and modeling studies based on European forest trees, the researchers conclude that leaf senescence will advance by 3 to 6 days by the end of the 21st century rather than lengthening by 1 to 3 weeks as current phenological models have predicted.
Arbuscular mycorrhizal fungi enhance mineralization of organic phosphorus (P) by carrying bacteria along their extraradical hyphae
Arbuscular mycorrhizal (AM) fungi gain access to nutrient patches outside the rhizosphere by producing an extensive network of fine hyphae. Jiang et al. focused on establishing the mechanism by which AM fungal hyphae reach discrete organic patches with a cohort of functional bacteria transported in a biofilm on their surface. They investigated the mechanisms and impact of the translocation of phosphate solubilizing bacteria (PSB) along AM fungal hyphae in bespoke microcosms. An in vitro culture experiment was also conducted to determine the direct impact of hyphal exudates of AM fungi upon the growth of PSB.