Structural Similarities and Overlapping Activities among Dihydroflavonol 4-Reductase, Flavanone 4-Reductase, and Anthocyanidin Reductase Offer Metabolic Flexibility in the Flavonoid Pathway.

Flavonoids are potent antioxidants that play a role in defense against pathogens, UV-radiation, and the detoxification of reactive oxygen species. Dihydroflavonol 4-reductase (DFR) and flavanone 4-reductase (FNR) reduce dihydroflavonols and flavanones, respectively, using NAD(P)H to produce flavan-(3)-4-(di)ols in flavonoid biosynthesis. Anthocyanidin reductase (ANR) reduces anthocyanidins to flavan-3-ols.

Differential Defense Responses of Upland and Lowland Switchgrass Cultivars to a Cereal Aphid Pest.

Yellow sugarcane aphid (YSA) (, Forbes) is a damaging pest on many grasses. Switchgrass ( L.), a perennial C4 grass, has been selected as a bioenergy feedstock because of its perceived resilience to abiotic and biotic stresses.

Aphid-Responsive Defense Networks in Hybrid Switchgrass.

Aphid herbivory elicits plant defense-related networks that are influenced by host genetics. Plants of the upland switchgrass ( ) cultivar Summer can be a suitable host for greenbug aphids (; GB), and yellow sugarcane aphids (, YSA), whereas the lowland cultivar Kanlow exhibited multi-species resistance that curtails aphid reproduction. However, stabilized hybrids of Summer (♀) x Kanlow (♂) (SxK) with improved agronomics can be damaged by both aphids.

Seasonal below-ground metabolism in switchgrass.

Switchgrass (Panicum virgatum), a perennial, polyploid, C4 warm-season grass is among the foremost herbaceous species being advanced as a source of biomass for biofuel end uses. At the end of every growing season, the aerial tissues senesce, and the below-ground rhizomes become dormant. Future growth is dependent on the successful over-wintering of the rhizomes.

Overexpression of SbMyb60 in Sorghum bicolor impacts both primary and secondary metabolism.

Few transcription factors have been identified in C grasses that either positively or negatively regulate monolignol biosynthesis. Previously, the overexpression of SbMyb60 in sorghum (Sorghum bicolor) has been shown to induce monolignol biosynthesis, which leads to elevated lignin deposition and altered cell wall composition. To determine how SbMyb60 overexpression impacts other metabolic pathways, RNA-Seq and metabolite profiling were performed on stalks and leaves.

Transcriptional analysis of defense mechanisms in upland tetraploid switchgrass to greenbugs.

Background: Aphid infestation of switchgrass (Panicum virgatum) has the potential to reduce yields and biomass quality. Although switchgrass-greenbug (Schizaphis graminum; GB) interactions have been studied at the whole plant level, little information is available on plant defense responses at the molecular level.

Results: The global transcriptomic response of switchgrass cv Summer to GB was monitored by RNA-Seq in infested and control (uninfested) plants harvested at 5, 10, and 15 days after infestation (DAI).

Identification of an orthologous clade of peroxidases that respond to feeding by greenbugs (Schizaphis graminum) in C grasses.

Knowledge of specific peroxidases that respond to aphid herbivory is limited in C4 grasses, but could provide targets for improving defence against these pests. A sorghum (Sorghum bicolor (L.) Moench) peroxidase (SbPrx-1; Sobic.

Insect and plant-derived miRNAs in greenbug (Schizaphis graminum) and yellow sugarcane aphid (Sipha flava) revealed by deep sequencing.

Schizaphis graminum (green bug; GB) and Sipha flava (yellow sugarcane aphid; YSA) are two cereal aphid species with broad host ranges capable of establishing on sorghum (Sorghum bicolor) and several switchgrass (Panicum virgatum) cultivars. Switchgrass and sorghum are staple renewable bioenergy crops that are vulnerable to damage by aphids, therefore, identifying novel targets to control aphids has the potential to drastically improve yields and reduce losses in these bioenergy crops. Despite the wealth of genomic and transcriptomic information available from a closely related model aphid species, the pea aphid (Acyrthosiphon pisum), similar genomic information, including the identification of small RNAs, is still limited for GB and YSA.

Overexpression of SbMyb60 impacts phenylpropanoid biosynthesis and alters secondary cell wall composition in Sorghum bicolor.

The phenylpropanoid biosynthetic pathway that generates lignin subunits represents a significant target for altering the abundance and composition of lignin. The global regulators of phenylpropanoid metabolism may include MYB transcription factors, whose expression levels have been correlated with changes in secondary cell wall composition and the levels of several other aromatic compounds, including anthocyanins and flavonoids. While transcription factors correlated with downregulation of the phenylpropanoid biosynthesis pathway have been identified in several grass species, few transcription factors linked to activation of this pathway have been identified in C4 grasses, some of which are being developed as dedicated bioenergy feedstocks.

Transcriptional Profiling of Resistant and Susceptible Buffalograsses in Response to Blissus occiduus (Hemiptera: Blissidae) Feeding.

Understanding plant resistance mechanisms at a molecular level would provide valuable insights into the biological pathways impacted by insect feeding, and help explain specific plant tolerance mechanisms. As a first step in this process, we conducted next-generation sequencing using RNA extracted from chinch bug-tolerant and -susceptible buffalograss genotypes at 7 and 14 d after chinch bug feeding. Sequence descriptions and gene ontology terms were assigned to 1,701 differentially expressed genes.

Contrasting metabolism in perenniating structures of upland and lowland switchgrass plants late in the growing season.

Background: Switchgrass (Panicum virgatum L.) is being developed as a bioenergy crop for many temperate regions of the world. One way to increase biomass yields is to move southern adapted lowland cultivars to more northern latitudes.

Expression profiling of four defense-related buffalograss transcripts in response to chinch bug (Hemiptera: Blissidae) feeding.

Oxidative enzymes are one of many key players in plant tolerance responses and defense signaling pathways. This study evaluated gene expression of four buffalograss transcripts (two peroxidases, a catalase, and a GRAS (gibberellic acid insensitive [GAI], repressor of GAI, and scarecrow) and total peroxidase activity in response to western chinch bug (Blissus occiduus Barber) feeding in susceptible and resistant buffalograsses (Buchloë dactyloides (Nuttall) Engelmann). Basal levels of all four transcripts were consistently higher in the resistant buffalograss when compared with the susceptible genotype, which suggests important physiological differences exist between the two buffalograsses.

Global changes in mineral transporters in tetraploid switchgrasses (Panicum virgatum L.).

Switchgrass (Panicum virgatum L) is perennial, C4 grass with great potential as a biofuel crop. An in-depth understanding of the mechanisms that control mineral uptake, distribution and remobilization will benefit sustainable production. Nutrients are mobilized from aerial portions to below-ground crowns and rhizomes as a natural accompaniment to above-ground senescence post seed-set.

Turnip crinkle virus coat protein inhibits the basal immune response to virus invasion in Arabidopsis by binding to the NAC transcription factor TIP.

Turnip crinkle virus (TCV) has been shown to interact with a NAC transcription factor, TIP, of Arabidopsis thaliana, via its coat protein (CP). This interaction correlates with the resistance response manifested in TCV-resistant Arabidopsis ecotype Di-17. We report that failure of a mutated CP to interact with TIP triggered the corresponding TCV mutant (R6A) to cause more severe symptoms in the TCV-susceptible ecotype Col-0.

Transcriptome analysis of two buffalograss cultivars.

Background: Buffalograss [Buchloë dactyloides (Nutt.) Engel. syn.

Abolishing activity against ascorbate in a cytosolic ascorbate peroxidase from switchgrass.

Switchgrass (Panicum virgatum L.) is being developed as a bioenergy species. Recently an early version of its genome has been released permitting a route to the cloning and analysis of key proteins.

Towards uncovering the roles of switchgrass peroxidases in plant processes.

Herbaceous perennial plants selected as potential biofuel feedstocks had been understudied at the genomic and functional genomic levels. Recent investments, primarily by the U.S.

Switchgrass PviCAD1: understanding residues important for substrate preferences and activity.

Cinnamyl alcohol dehydrogenase (CAD) catalyzes the final step in monolignol biosynthesis. Although plants contain numerous genes coding for CADs, only one or two CADs appear to have a primary physiological role in lignin biosynthesis. Much of this distinction appears to reside in a few key residues that permit reasonable catalytic rates on monolignal substrates.

Cloning and characterization of a caesalpinoid (Chamaecrista fasciculata) hemoglobin: the structural transition from a nonsymbiotic hemoglobin to a leghemoglobin.

Nonsymbiotic hemoglobins (nsHbs) and leghemoglobins (Lbs) are plant proteins that can reversibly bind O(2) and other ligands. The nsHbs are hexacoordinate and appear to modulate cellular concentrations of NO and maintain energy levels under hypoxic conditions. The Lbs are pentacoordinate and facilitate the diffusion of O(2) to symbiotic bacteroids within legume root nodules.

EST sequencing and phylogenetic analysis of the model grass Brachypodium distachyon.

Brachypodium distachyon (Brachypodium) is a temperate grass with the physical and genomic attributes necessary for a model system (small size, rapid generation time, self-fertile, small genome size, diploidy in some accessions). To increase the utility of Brachypodium as a model grass, we sequenced 20,440 expressed sequence tags (ESTs) from five cDNA libraries made from leaves, stems plus leaf sheaths, roots, callus and developing seed heads. The ESTs had an average trimmed length of 650 bp.

Analysis of expressed sequence tags and the identification of associated short tandem repeats in switchgrass.

Switchgrass is a large, North American, perennial grass that is being evaluated as a potential energy crop. Expressed sequence tags (ESTs) were generated from four switchgrass cv. "Kanlow" cDNA libraries to create a gene inventory of 7,810 unique gene clusters from a total of 11,990 individual sequences.