Inulin is an important reserve polysaccharide in Asteraceae plants, and is also widely used as a sweetener, a source of dietary fibre and prebiotic. Nevertheless, a lack of genomic resources for inulin‐producing plants has hindered extensive studies on inulin metabolism and regulation. Here, we present chromosome‐level reference genomes for four inulin‐producing plants: chicory (Cichorium intybus), endive (Cichorium endivia), great burdock (Arctium lappa) and yacon (Smallanthus sonchifolius), with assembled genome sizes of 1.28, 0.89, 1.73 and 2.72 Gb, respectively. We found that the chicory, endive and great burdock genomes were shaped by whole genome triplication (WGT‐1), and the yacon genome was shaped by WGT‐1 and two subsequent whole genome duplications (WGD‐2 and WGD‐3). A yacon unique whole genome duplication (WGD‐3) occurred 5.6–5.8 million years ago. Our results also showed the genome size difference between chicory and endive is largely due to LTR retrotransposons, and rejected a previous hypothesis that chicory is an ancestor of endive. Furthermore, we identified fructan‐active‐enzyme and transcription‐factor genes, and found there is one copy in chicory, endive and great burdock but two copies in yacon for most of these genes, except for the 1‐FEH II gene which is significantly expanded in chicory. Interestingly, inulin synthesis genes 1‐SST and 1‐FFT are located close to each other, as are the degradation genes 1‐FEH I and 1‐FEH II. Finally, we predicted protein structures for 1‐FFT genes to explore the mechanism determining inulin chain length.

Background The globe skimmer dragonfly (Pantala flavescens) is a notable Odonata insect distributed in nature fields and farmlands worldwide, and it is commonly recognized as a natural enemy because it preys on agricultural pests and health pests. As one of the sister groups of winged insects, odonatan species are key to understanding the evolution of insect wings. Findings We present a high-quality reference genome of P. flavescens, which is the first chromosome-level genome in the Palaeoptera (Odonata and Ephemeroptera). The assembled genome size was 662 Mb, with a contig N50 of 16.2 Mb. Via Hi-C scaffolding, 648 Mb (97.9%) of contig sequences were clustered, ordered, and assembled into 12 large scaffolds, each corresponding to a natural chromosome. The X chromosome was identified by sequence coverage depth. The repetitive sequences and gene density of the X chromosome are similar to those of autosomal sequences, but the X chromosome shows a much lower degree of heterozygosity. Our analysis shows that the effective population size experienced 3 declining events, which may have been caused by climate change and environmental pollution. Conclusions The genome of P. flavescens provides more information on the biology and evolution of insects and will help for the use of this species in pest control.

Background Due to the importance of chicken production and the remarkable influence of the gut microbiota on host health and growth, tens of thousands of metagenome-assembled genomes (MAGs) have been constructed for the chicken gut microbiome. However, due to the limitations of short-read sequencing and assembly technologies, most of these MAGs are far from complete, are of lower quality, and include contaminant reads. Results We generated 332 Gb of high-fidelity (HiFi) long reads from the 5 chicken intestinal compartments and assembled 461 and 337 microbial genomes, of which 53% and 55% are circular, at the species and strain levels, respectively. For the assembled microbial genomes, approximately 95% were regarded as complete according to the “RNA complete” criteria, which requires at least 1 full-length ribosomal RNA (rRNA) operon encoding all 3 types of rRNA (16S, 23S, and 5S) and at least 18 copies of full-length transfer RNA genes. In comparison with the short-read-derived chicken MAGs, 384 (83% of 461) and 89 (26% of 337) strain-level and species-level genomes in this study are novel, with no matches to previously reported sequences. At the gene level, one-third of the 2.5 million genes in the HiFi-derived gene catalog are novel and cannot be matched to the short-read-derived gene catalog. Moreover, the HiFi-derived genomes have much higher continuity and completeness, as well as lower contamination; the HiFi-derived gene catalog has a much higher ratio of complete gene structures. The dominant phylum in our HiFi-assembled genomes was Firmicutes (82.5%), and the foregut was highly enriched in 5 genera: Ligilactobacillus, Limosilactobacillus, Lactobacillus, Weissella, and Enterococcus, all of which belong to the order Lactobacillales. Using GTDB-Tk, all 337 species-level genomes were successfully classified at the order level; however, 2, 35, and 189 genomes could not be classified into any known family, genus, and species, respectively. Among these incompletely classified genomes, 9 and 49 may belong to novel genera and species, respectively, because their 16S rRNA genes have identities lower than 95% and 97% to any known 16S rRNA genes. Conclusions HiFi sequencing not only produced metagenome assemblies and gene structures with markedly improved quality but also recovered a substantial portion of novel genomes and genes that were missed in previous short-read-based metagenome studies. The novel genomes and species obtained in this study will facilitate gut microbiome and host–microbiota interaction studies, thereby contributing to the sustainable development of poultry resources.

Cereal crop Zn biofortification is an effective solution to global human Zn deficiency and is achieved by increasing grain Zn concentration concurrently with yield. However, the desired grain Zn concentration (>40 mg kg−1) is rarely observed for high-yielding wheat on calcareous soils, owing to inadequate Zn uptake or Zn distribution to grain. This study was designed to determine how much Zn uptake or distribution is adequate for Zn biofortification, by considering 123 bread wheat (Triticum aestivum L.) cultivars grown on calcareous soils with low available Zn (<0.5 mg kg−1) in the field on the southern Loess Plateau, China. Nineteen high-yielding cultivars were identified with similar yields (∼7.0 t ha−1) and various grain Zn concentrations from 9.3 to 26.7 mg kg−1. Adequate Zn distribution to grain was defined as the situation where the Zn harvest index at maturity increased to its maximum of ∼91.0% and straw Zn concentration at maturity decreased to its minimum of ∼1.5 mg kg−1. For each cultivar, the extra Zn in straw above the minimum could be again remobilised to grain and raise grain Zn concentration to its highest attainable level, which was 14.5–31.3 mg kg−1 for the 19 high-yielding cultivars but still <40 mg kg−1. Thus, the current Zn uptake needs to be increased to ≥308 g ha−1 to achieve Zn biofortification on low-Zn calcareous soils. For other wheat production regions, the method established here can also provide the priority measures and quantitative guidelines for Zn biofortification.