Combination of Single-Molecule Long-Read Sequencing and Illumina Sequencing Revealed the Mechanism of Anthocyanins Accumulation in an Ornamental Grass, Pennisetum Setaceum ‘Rubrum’

Pennisetum setaceum ‘Rubrum’ is an ornamental herb with purple leaves, and it is widely used in the construction of landscaping. However, the current next generation sequencing (NGS) transcriptome information is not satisfactory mainly because of the enormous difficulty in obtaining full-length transcripts. What’s more, the molecular mechanisms of anthocyanin accumulation have not been thoroughly studied. In this study, we used PacBio full-length transcriptome sequencing combined with NGS sequencing technology to conduct transcriptome analysis on leaves showing different colors at different stages to clarify the molecular mechanism involved in the color change of P. setaceum ‘Rubrum’. A total of 280,413 full-length non-chimeric reads (FLNC) sequences were obtained based on single-molecule long-read sequencing technology. We obtained 140,633 high quality (HQ) transcripts and 2,683 low quality (LQ) transcripts and identified 5,352 alternative splicing (AS). In addition, a total of 93,066 ORFs, including 57,457 full open links and 2,910 lncRNA sequences were screened out. Furthermore, a total of 10,795 differentially expressed genes were identified. Gene ontology (GO) cluster and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed the underlying mechanism of anthocyanin accumulation. In this study, to our best knowledge, we provided the full-length transcriptome information of P. setaceum ‘Rubrum’ for the first time. The underlying mechanism of anthocyanin accumulation in P. setaceum ‘Rubrum’ was further discussed based on the newly generated transcriptome data. The information will not only facilitate the gene function studies but also pave the way for future breeding projects of Pennisetum setaceum .

Mechanical and Thermal Properties of Insulating Sustainable Mortars with Ampelodesmos Mauritanicus and Pennisetum Setaceum Plants as Aggregates

The use of natural fibers in cement composites is a widening research field as their application can enhance the mechanical and thermal behavior of cement mortars and limit their carbon footprint. In this paper, two different wild grasses, i.e., Ampelodesmos Mauritanicus, also called diss, and Pennisetum Setaceum, also known as crimson fountaingrass, are used as a source of natural aggregates for cement mortars. The main purpose is to assess the possibility of using the more invasive crimson fountaingrass in place of diss in cement-based vegetable concrete. The two plant fibers have been characterized by means of scanning electron microscopy (SEM), helium picnometry and thermogravimetric analysis. Moreover, the thermal conductivity of fiber panels has been measured. Mortars samples have been prepared using untreated, boiled and Polyethylene glycol 4000 (PEG) treated fibers. The mechanical characterization has been performed by means of three point bending and compression tests. Thermal conductivity and porosity have been measured to characterize physical modification induced by fibers’ treatments. The results showed better thermal and mechanical properties of diss fiber composites than fountaingrass one and that fiber treatments lead to a reduction of the thermal insulation properties.

Screening of key genes responsible for Pennisetum setaceum ‘Rubrum’ leaf color using transcriptome sequencing

Pennisetum setaceum ‘Rubrum’ is an ornamental grass plant that produces purple leaves in high-light environments and light purple or green leaves in low-light environments, the latter of which greatly reduces its aesthetic appeal. Therefore, we aimed to identify the key genes associated with leaf coloration and elucidate the molecular mechanisms involved in the color changes in P. setaceum ‘Rubrum’ leaves. We performed transcriptome sequencing of P. setaceum ‘Rubrum’ leaves before and after shading. A total of 19,043 differentially expressed genes were identified, and the numbers of upregulated and downregulated genes at T1 stage, when compared with their expression at the T0 stage, were 10,761 and 8,642, respectively. The possible pathways that determine P. setaceum ‘Rubrum’ leaf color included flavonoid biosynthesis, flavone and flavonol biosynthesis, and carotenoid biosynthesis. There were 31 differentially expressed genes related to chlorophyll metabolism, of which 21 were related to chlorophyll biosynthesis and 10 to chlorophyll degradation, as well as three transcription factors that may be involved in the regulation of chlorophyll degradation. There were 31 key enzyme genes involved in anthocyanin synthesis and accumulation in P. setaceum ‘Rubrum’ leaves, with four transcription factors that may be involved in the regulation of anthocyanin metabolism. The transcriptome data were verified and confirmed reliable by real-time fluorescence quantitative PCR analysis. These findings provide a genetic basis for improving leaf color in P. setaceum ‘Rubrum.’

Poaceae with PGPR Bacteria and Arbuscular Mycorrhizae Partnerships as a Model System for Plant Microbiome Manipulation for Phytoremediation of Petroleum Hydrocarbons Contaminated Agricultural Soils

Total petroleum hydrocarbons (TPHs) are a persistent environmental organic contaminant. The possibility of obtaining synergistic effects between plants and microorganisms has further increased the possibility of alternative techniques for bioremediation. Oloptum miliaceum (L.) Röser & H.R. Hamasha and Pennisetum setaceum (Forssk.) Chiov. are, undoubtedly, good model plants for phytoremediation because they have large roots, leaf biomass, and a fast and effective renewal capacity, also, they have a great capacity to host endophytes in their roots. Gas chromatography-mass spectrometry (GC-MS) based on carbon fraction number was a basic technique used to determine the hydrocarbon degradation, and microorganism’s population was identified by high-throughput sequencing of 16s rRNA. The microbial consortium used allows the plant to increase overall biomass, adapt more in terms of redox biology (Superoxide dismutase SOD, catalase CAT, ascorbate peroxidase APX, guaiacol peroxidase GPX), and stress markers (Glutathione S-transferase GST, Phenylalanine Ammonia Lyase PAL, Proline content, and lipid peroxidation MDA). In addition, the photosynthetic efficiency and the soil dehydrogenase activity were monitored. After 240 days, the percentage of TPHs removed in Group 2 was 94%, whereas in Group 1, it was 78% in Oloptum miliaceum and Pennisetum setaceum. The removal of aliphatic hydrocarbons (C13–C36) was observed in Oloptum miliaceum and Pennisetum setaceum inoculated with the consortium of indigenous bacteria selected from rhizosphere soil and mycorrhizae strains. Our data demonstrate that, the Poaceae, in relation to its great ecological and vegetative potential, could be a great candidate for extensive remediation of soils contaminated by TPHs.