SMRT sequencing of a full-length transcriptome reveals transcript variants involved in C18 unsaturated fatty acid biosynthesis and metabolism pathways at chilling temperature in Pennisetum giganteum.

BACKGROUND: Pennisetum giganteum, an abundant, fast-growing perennial C4 grass that belongs to the genus Pennisetum, family Poaceae, has been developed as a source of biomass for mushroom cultivation and production, as a source of forage for cattle and sheep, and as a tool to remedy soil erosion. However, having a chilling-sensitive nature, P. giganteum seedlings need to be protected while overwintering in most temperate climate regions. RESULTS: To elucidate the cold stress responses of P. giganteum, we carried out comprehensive full-length transcriptomes from leaf and root tissues under room temperature (RT) and chilling temperature (CT) using PacBio Iso-Seq long reads. We identified 196,124 and 140,766 full-length consensus transcripts in the RT and CT samples, respectively. We then systematically performed functional annotation, transcription factor identification, long non-coding RNAs (lncRNAs) prediction, and simple sequence repeat (SSR) analysis of those full-length transcriptomes. Isoform analysis revealed that alternative splicing events may be induced by cold stress in P. giganteum, and transcript variants may be involved in C18 unsaturated fatty acid biosynthesis and metabolism pathways at chilling temperature in P. giganteum. Furthermore, the fatty acid composition determination and gene expression level analysis supported that C18 unsaturated fatty acid biosynthesis and metabolism pathways may play roles during cold stress in P. giganteum. CONCLUSIONS: We provide the first comprehensive full-length transcriptomic resource for the abundant and fast-growing perennial grass Pennisetum giganteum. Our results provide a useful transcriptomic resource for exploring the biological pathways involved in the cold stress responses of P. giganteum.

Dibromomethane Knitted Highly Porous Hyper-Cross-Linked Polymers for Efficient High-Pressure Methane Storage.

Hyper-cross-linked polymers (HCPs) with ultra-high porosity, superior physicochemical stability, and excellent cost-effectiveness are attractive candidates for methane storage. However, the construction of HCPs with BET surface areas exceeding 3000 m2 g-1 remains extremely challenging. In this work, a newly developed DBM-knitting method with a slow-knitting rate is employed to increase the cross-linking degree, in which dichloromethane (DCM) is replaced by dibromomethane (DBM) as both solvent and electrophilic cross-linker, resulting in highly porous and physicochemically stable HCPs. The BET surface areas of DBM-knitted SHCPs-Br are 44%-120% higher than that of DCM-knitted SHCPs-Cl using the same building blocks. Remarkably, SHCP-3-Br exhibits an unprecedentedly high porosity (SBET = 3120 m2 g-1) among reported HCPs, and shows a competitive volumetric 5-100 bar working methane capacity of 191 cm3 (STP) cm-3 at 273 K calculated by using real packing density, which outperforms sate-of-art metal-organic framework (MOFs) at comparable conditions. This facile and versatile low-knitting-rate strategy enables effective improvement in the porosity of HCPs for porosity-desired applications.