Characterization of a Stress-Enhanced Promoter from the Grass Halophyte, Spartina alterniflora L.

Stress-inducible promoters are vital for the desirable expression of genes, especially transcription factors, which could otherwise compromise growth and development when constitutively overexpressed in plants. Here, we report on the characterization of the promoter region of a stressresponsive gene SaAsr1 from monocot halophyte cordgrass (Spartina alterniflora). Several cis-acting elements, such as ABRE (ABA-responsive element), DRE-CRT (dehydration responsive-element/CRepeat), LTRE (low temperature-responsive element), ERE (ethylene-responsive element), LRE (light-responsive element), etc. contributed at varying degrees to salt-, drought- and ABA-enhanced expression of gusA reporter gene in Arabidopsis thaliana under the full-length promoter, pAsr11875 and its deletion derivatives with an assortment of cis-regulatory motifs. The smallest promoter, pAsr1491, with three cis-acting elements (a CCAAT box-heat responsive, an LRE, and a copper responsive element) conferred drought-enhanced expression of gusA; pAsr1755 (with an ABRE and a DRE) presented the highest expression in ABA and drought; and pAsr1994 with seven ABREs and two DREs conferred optimal induction of gusA, especially under drought and ABA. Arabidopsis transgenics expressing a known abiotic stress-responsive gene, SaADF2 (actin depolymerization factor 2), under both pAsr11875 and p35S promoters outperformed the wild type (WT) with enhanced drought and salt tolerance contributed by higher relative water content and membrane stability with no significant difference between pAsr11875:SaADF2 or p35S:SaADF2 lines. However, pAsr11875:SaADF2 lines produced healthy plants with robust shoot systems under salt stress and control compared to slightly stunted growth of the p35S:SaADF2 plants. This reestablished the evidence that transgene expression under a stress-inducible promoter is a better strategy for the genetic manipulation of crops

Rice H2A.Z negatively regulates genes responsive to nutrient starvation but promotes expression of key housekeeping genes

© The Author(s) 2018. Published by Oxford University Press on behalf of the Society for Experimental Biology. The H2A.Z histone variant plays a role in the modulation of environmental responses, but the nature of the associated mechanisms remains enigmatic. We investigated global H2A.Z deposition and transcriptomic changes in rice (Oryza sativa) upon exposure to phosphate (Pi) deficiency and in response to RNAi knockdown of OsARP6, which encodes a key component of the H2A.Z exchange complex. Both Pi deficiency and OsARP6-knockdown resulted in similar, profound effects on global H2A.Z distribution. H2A.Z in the gene body of stress-responsive genes was negatively correlated with gene expression, and this was more apparent in response to Pi deficiency. In contrast, the role of H2A.Z at the transcription start site (TSS) was more context dependent, acting as a repressor of some stress-responsive genes, but an activator of some genes with housekeeping functions. This was especially evident upon OsARP6-knockdown, which resulted in down-regulation of a number of genes linked to chloroplast function that contained decreases in H2A.Z at the TSS. Consistently, OsARP6-RNAi plants exhibited lower chlorophyll content relative to the wild-type. Our results demonstrate that gene body-localized H2A.Z plays a prominent role in repressing stress-responsive genes under non-inductive conditions, whereas H2A.Z at the TSS functions as a positive or negative regulator of transcription

Investigational new drug enabling angiotensin oral-delivery studies to attenuate pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a deadly and uncurable disease characterized by remodeling of the pulmonary vasculature and increased pulmonary artery pressure. Angiotensin Converting Enzyme 2 (ACE2) and its product, angiotensin-(1-7) [ANG-(1-7)] were expressed in lettuce chloroplasts to facilitate affordable oral drug delivery. Lyophilized lettuce cells were stable up to 28 months at ambient temperature with proper folding, assembly of CTB-ACE2/ANG-(1-7) and functionality. When the antibiotic resistance gene was removed, Ang1-7 expression was stable in subsequent generations in marker-free transplastomic lines. Oral gavage of monocrotaline-induced PAH rats resulted in dose-dependent delivery of ANG-(1-7) and ACE2 in plasma/tissues and PAH development was attenuated with decreases in right ventricular (RV) hypertrophy, RV systolic pressure, total pulmonary resistance and pulmonary artery remodeling. Such attenuation correlated well with alterations in the transcription of Ang-(1-7) receptor MAS and angiotensin II receptor AGTRI as well as IL-1β and TGF-β1. Toxicology studies showed that both male and female rats tolerated ~10-fold ACE2/ANG-(1-7) higher than efficacy dose. Plant cell wall degrading enzymes enhanced plasma levels of orally delivered protein drug bioencapsulated within plant cells. Efficient attenuation of PAH with no toxicity augurs well for clinical advancement of the first oral protein therapy to prevent/treat underlying pathology for this disease

Genetic Mapping of Quantitative Trait Loci for Grain Yield under Drought in Rice under Controlled Greenhouse Conditions

Drought stress is a constant threat to rice production worldwide. Most modern rice cultivars are sensitive to drought, and the effect is severe at the reproductive stage. Conventional breeding for drought resistant (DR) rice varieties is slow and limited due to the quantitative nature of the DR traits. Identification of genes (QTLs)/markers associated with DR traits is a prerequisite for marker-assisted breeding. Grain yield is the most important trait and to this end drought yield QTLs have been identified under field conditions. The present study reports identification of drought yield QTLs under controlled conditions without confounding effects of other factors prevalent under natural conditions. A linkage map covering 1,781.5 cM with an average resolution of 9.76 cM was constructed using an F2 population from a cross between two Japonica cultivars, Cocodrie (drought sensitive) and Vandana (drought tolerant) with 213 markers distributed over 12 rice chromosomes. A subset of 59 markers (22 genic SSRs and 37 SNPs) derived from the transcriptome of the parents were also placed in the map. Single marker analysis using 187 F2 : 3 progeny identified 6 markers distributed on chromosomes 1, 5, and 8 to be associated with grain yield under drought (GYD). Composite interval mapping identified six genomic regions/quantitative trait loci (QTL) on chromosome 1, 5, 8, and 9 to be associated with GYD. QTLs located on chromosome 1 (qGYD1.2, qGYD1.3), chromosome 5 (qGYD5.1) and chromosome 8 (qGYD8.1) were contributed by Vandana alleles, whereas the QTLs, qGYD1.1 and qQYD9.1 were contributed by Cocodrie alelles. The additive positive phenotypic variance explained by the QTLs ranged from 30.0 to 34.0%. Candidate genes annotation within QTLs suggested the role of transcription factors and genes involved in osmotic potential regulation through catalytic/metabolic pathways in drought tolerance mechanism contributing to yield

Additional file 4: Table S2. of Transcriptome analysis of smooth cordgrass (Spartina alterniflora Loisel), a monocot halophyte, reveals candidate genes involved in its adaptation to salinity

Simple sequence repeats (SSRs), flanking primers and their predicted location in Spartina alterniflora unigenes. (XLSX 357Â kb

Additional file 4: Table S2. of Transcriptome analysis of smooth cordgrass (Spartina alterniflora Loisel), a monocot halophyte, reveals candidate genes involved in its adaptation to salinity

Simple sequence repeats (SSRs), flanking primers and their predicted location in Spartina alterniflora unigenes. (XLSX 357Â kb

Additional file 3: Table S1. of Transcriptome analysis of smooth cordgrass (Spartina alterniflora Loisel), a monocot halophyte, reveals candidate genes involved in its adaptation to salinity

Protein families found in Spartina alterniflora unigenes retrieved from Pfam database. (XLSX 229 kb

Additional file 2: Figure S1. of Transcriptome analysis of smooth cordgrass (Spartina alterniflora Loisel), a monocot halophyte, reveals candidate genes involved in its adaptation to salinity

Percentage distribution of GC content between Spartina alterniflora and rice genes. Figure S2 Gene family distribution among the four monocots, Spartina alterniflora (Sa), Oryza sativa (Os), Sorghum bicolor (Sb) and Zea mays (Zm). The homologous genes from each monocot species were clustered to represent gene family. The number of homologous genes shared by different species is represented by gene families at intersection. Figure S3 Functional GO terms for gene families specific to Spartina alterniflora indicating coverage of different functional category genes specific to S. alterniflora. Figure S4 A histogram showing the GC content distribution in different sets of genes of Spartina alterniflora. NP, set of genes having similarity outside of poaceae; PS, poaceae specific genes; All, whole S. alterniflora transcriptome; and SS, S. alterniflora-specific genes. Figure S5 Distribution of different repeat unit size of the SSRs identified in Spartina alterniflora transcriptome. Figure S6 Distribution of different types of SSR motifs in Spartina alterniflora unigenes. Figure S7 Representative gel showing DNA profile of 13 (CP1 through CP13) Spartina alterniflora accessions produced by five SSR primers derived from the contigs. (PPTX 778 kb

Additional file 1: of Transcriptome analysis of smooth cordgrass (Spartina alterniflora Loisel), a monocot halophyte, reveals candidate genes involved in its adaptation to salinity

The comparative analysis among Spartina alterniflora reads with reads of Salterniflora [34] and unigenes of S. pectinata [78]. (XLSX 154 kb