Uncovering the role of a positive selection site of wax ester synthase/diacylglycerol acyltransferase in two closely related Stipa species in wax ester synthesis under drought stress

Abstract Natural selection drives local adaptations of species to biotic or abiotic environmental stresses. As a result, adaptive phenotypic divergence can evolve among related species living in different habitats. However, the genetic foundation of this divergence process remains largely unknown. Two closely related alpine grass species, Stipa capillacea and Stipa purpurea, are distributed in different rainfall regions of northern Tibet. Here, we analyzed the drought tolerance of these two closely related Stipa species, and found that S. purpurea was more resistance to drought stress than S. capillacea. To further understand the genetic diversity behind their adaptation to drought environments, a comprehensive gene repertoire was generated using PacBio isoform and Illumina RNA sequencing technologies. Bioinformatics analyses revealed that differential transcripts were mainly enriched in the wax synthetic pathway, and a threonine residue at position 239 of WSD1 was identified as having undergone positive selection in S. purpurea. Using heterologous expression in the Saccharomyces cerevisiae mutant H1246, site-directed mutagenesis studies demonstrated that a positive selection site results in changes to the wax esters profile. This difference may play an important role in S. purpurea in response to drought conditions, indicating that S. purpurea has evolved specific strategies involving its wax biosynthetic pathway as part of its long-term adaptation to the Qinghai–Tibet Plateau.

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Physiological, Biochemical and Molecular Mechanisms Regulating Post-Drought Stress Recovery in Grass Species

Handbook of Plant and Crop Stress, Fourth Edition ◽

10.1201/9781351104609-3 ◽

2019 ◽

pp. 41-49

Author(s):

Cathryn Chapman ◽

Bingru Huang

Keyword(s):

Drought Stress ◽

Molecular Mechanisms ◽

Grass Species ◽

Stress Recovery

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Drought tolerance molecular responses of two cultivated varieties Jerusalem artichoke (Helianthus tuberosus L.) as revealed by RNA-Seq

10.21203/rs.3.rs-124586/v1 ◽

2020 ◽

Author(s):

Shipeng Yang ◽

Lihui Wang ◽

Qiwen Zhong ◽

Guangnan Zhang ◽

Haiwang Zhang ◽

...

Keyword(s):

Drought Stress ◽

Drought Resistance ◽

Metabolic Pathways ◽

Jerusalem Artichoke ◽

Tibet Plateau ◽

Helianthus Tuberosus ◽

Rna Seq ◽

Concentration Gradients ◽

Light Reaction ◽

Metabolic Activities

Abstract Background Jerusalem artichoke (Helianthus tuberosus L.) is a highly stress-resistant crop, especially it grows normally in the desertified land of Qinghai-Tibet Plateau in the past two years, and has become a crop with agricultural, industrial and ecological functions. However, there are few studies on drought resistance of Jerusalem artichoke at present, and studies on the mechanisms of stress resistance of Jerusalem artichoke breeding and fructan are seriously lagging behind. In this study, we selected two differentially resistant cultivars for drought stress experiments with different concentration gradients, the aim was finding DEGs and metabolic pathways associated with drought stress. Results Based on an additional analysis of the metabolic pathways under drought stress using MapMan, the most different types of metabolism included secondary metabolism, light reaction metabolism and cell wall. As a whole, QY1 and QY3 both had a large number of up-regulated genes in the flavor pathway. It was suggested that flavonoids could help Jerusalem artichoke to resist drought stress and maintain normal metabolic activities. In addition, the gene analysis of the abscisic acid (ABA) key metabolic pathway showed that QY3 had more genes in NAC and WRKY than QY1, but QY1 had more genes in response to drought stress as a whole. By combining RNA-Seq and WGCNA, a weighted gene co-expression network was constructed and divided into modules. By analyzing specifically the expressed modules, four modules were found to have the highest correlation with drought. Further research on the genes revealed that all 16 genes related to histone, ABA and protein kinase had the highest significance in these pathways. Conclusions These findings represent the first RNA-Seq analysis of drought stress in Jerusalem artichoke, which is of substantial significance to explore the function of drought resistance in Jerusalem artichoke and the excavation of related genes.

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Diversity and Functions of Endophytic Fungi Associated with Roots and Leaves of Stipa purpurea in an Alpine Steppe at Qinghai-Tibet Plateau

Journal of Microbiology and Biotechnology ◽

10.4014/jmb.2002.02056 ◽

2020 ◽

Vol 30 (7) ◽

pp. 1027-1036

Author(s):

Xiaoyan Yang ◽

Hui Jin ◽

Lihong Xu ◽

Haiyan Cui ◽

Aiyi Xin ◽

...

Keyword(s):

Endophytic Fungi ◽

Tibet Plateau ◽

Alpine Steppe ◽

Stipa Purpurea ◽

Qinghai Tibet Plateau

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Growth and Physiological Traits Associated with Drought Survival and Post-drought Recovery in Perennial Turfgrass Species

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.135.2.125 ◽

2010 ◽

Vol 135 (2) ◽

pp. 125-133 ◽

Cited By ~ 35

Author(s):

Qi Chai ◽

Fang Jin ◽

Emily Merewitz ◽

Bingru Huang

Keyword(s):

Cell Wall ◽

Drought Stress ◽

Osmotic Adjustment ◽

Perennial Grass ◽

Kentucky Bluegrass ◽

Physiological Traits ◽

Grass Species ◽

Cell Wall Elasticity ◽

Drought Recovery ◽

Drought Survival

The objective of this study was to determine physiological traits for drought survival and post-drought recovery upon re-watering in two C3 perennial grass species, kentucky bluegrass [KBG (Poa pratensis)] and perennial ryegrass [PRG (Lolium perenne)]. Plants were maintained well watered or exposed to drought stress by withholding irrigation and were then re-watered in a growth chamber. KBG had significantly higher grass quality and leaf photochemical efficiency, and lower electrolyte leakage than PRG during 20 days of drought. After 7 days of re-watering, drought-damaged leaves were rehydrated to the control level in KBG, but could not fully recover in PRG. KBG produced a greater number of new roots, while PRG had more rapid elongation of new roots after 16 days of re-watering. Superior drought tolerance in KBG was associated with osmotic adjustment, higher cell wall elasticity, and lower relative water content at zero turgor. Osmotic adjustment, cell wall elasticity, and cell membrane stability could play important roles in leaf desiccation tolerance and drought survival in perennial grass species. In addition, post-drought recovery of leaf hydration level and physiological activity could be associated with the accumulation of carbohydrates in leaves and rhizomes during drought stress and new root production after re-watering.

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Transcriptional Regulation of Hydrogen Peroxide and Calcium for Signaling Transduction and Stress-defensive Genes Contributing to Improved Drought Tolerance in Creeping Bentgrass

Journal of the American Society for Horticultural Science ◽

10.21273/jashs04901-19 ◽

2020 ◽

Vol 145 (4) ◽

pp. 236-246

Author(s):

Zhou Li ◽

Yan Peng ◽

Bingru Huang

Keyword(s):

Transcription Factors ◽

Drought Stress ◽

Drought Tolerance ◽

Creeping Bentgrass ◽

Grass Species ◽

Regulation Of Transcription ◽

Signaling Transduction ◽

Genes Expression ◽

Protective Genes ◽

Ca Signaling

Small molecules, including H2O2 and Ca, mediate stress signaling and drought tolerance in plants. The objective of this study was to determine whether improvement in drought tolerance by H2O2 and Ca were associated with the regulation of transcription factors and stress-protective genes in perennial grass species. Plants of creeping bentgrass (Agrostis stolonifera) were sprayed with water (control), H2O2 (9 mm), or CaCl2 (10 mm) and exposed to drought stress for 20 days in controlled-environment growth chambers. Foliar application of H2O2 or Ca led to significant improvement in drought tolerance of creeping bentgrass, as demonstrated by greater turf quality, leaf relative water content, chlorophyll content, photochemical efficiency, and cell membrane stability, as compared with the untreated control. The application of H2O2 and Ca resulted in significant up-regulation of genes in Ca signaling transduction pathways [Ca-dependent kinase 26 (CDPK26), mitogen-activated protein kinase 1 (MAPK1), and 14-3-3] and transcript factors (WRKY75 and MYB13). For genes encoding antioxidant enzymes, H2O2 mainly enhanced superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), and dehydroascorbate reductase (DHAR) expression, while Ca primarily improved transcript levels of SOD, monodehydroascorbate reductase (MDHAR), and GR. In addition, heat shock protein 70 (HSP70), metallothionein 1 (MT1), and glutamine synthetase 2 (GS2) were also markedly up-regulated by H2O2 and Ca under drought stress. However, the transcript level of lipoxygenase 3 (LOX3) was significantly down-regulated by H2O2 and Ca under well-watered and drought conditions. These results imply that H2O2 and Ca commonly or differentially regulate genes expression in association with drought tolerance through activating Ca signaling pathway and regulating transcription factors and stress-protective genes expression, leading to the alleviation of lipid peroxidation, maintenance of correct protein folding and translocation, and enhancement of nitrogen metabolism under a prolonged period of drought stress in creeping bentgrass.

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Phyllosphere community assembly and response to drought stress on common tropical and temperate forage grasses

10.1101/2021.05.10.443535 ◽

2021 ◽

Author(s):

Emily K. Bechtold ◽

Stephanie Ryan ◽

Sarah E. Moughan ◽

Ravi Ranjan ◽

Klaus Nüsslein

Keyword(s):

Microbial Community ◽

Drought Stress ◽

Bacterial Community ◽

Community Assembly ◽

Community Diversity ◽

Grass Species ◽

Severe Drought ◽

Hormone Production ◽

Plant Host ◽

Bacterial Community Diversity

Grasslands represent a critical ecosystem important for global food production, soil carbon storage, and water regulation. Current intensification and expansion practices add to the degradation of grasslands and dramatically increase greenhouse gas emissions and pollution. Thus, new ways to sustain and improve their productivity are needed. Research efforts focus on the plant-leaf microbiome, or phyllosphere, because its microbial members impact ecosystem function by influencing pathogen resistance, plant hormone production, and nutrient availability through processes including nitrogen fixation. However, little is known about grassland phyllospheres and their response to environmental stress. In this study, globally dominant temperate and tropical forage grass species were grown in a greenhouse under current climate conditions and drought conditions that mimic future climate predictions to understand if (i) plant host taxa influence microbial community assembly, (ii) microbial communities respond to drought stress, and (iii) phyllosphere community changes correlate to changes in plant host traits and stress-response strategies. Community analysis using high resolution sequencing revealed Gammaproteobacteria as the dominant bacterial class, which increased under severe drought stress on both temperate and tropical grasses while overall bacterial community diversity declined. Bacterial community diversity, structure, and response to drought were significantly different between grass species. This community dependence on plant host species correlated with differences in grass species traits, which became more defined under drought stress conditions, suggesting symbiotic evolutionary relationships between plant hosts and their associated microbial community. Further understanding these strategies and the functions microbes provide to plants will help us utilize microbes to promote agricultural and ecosystem productivity in the future.

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Distinct evolutionary trajectories of V1R clades across mouse species

10.21203/rs.2.22451/v3 ◽

2020 ◽

Author(s):

Caitlin H Miller ◽

Polly Campbell ◽

Michael J Sheehan

Keyword(s):

Positive Selection ◽

House Mouse ◽

Gene Family Evolution ◽

Specific Gene ◽

Receptor Subtypes ◽

Gene Repertoire ◽

Social Signals ◽

Functional Roles ◽

Wide Range ◽

Evolutionary Trajectories

Abstract BACKGROUND: Many animals rely heavily on olfaction to navigate their environment. Among rodents, olfaction is crucial for a wide range of social behaviors. The vomeronasal olfactory system in particular plays an important role in mediating social communication, including the detection of pheromones and recognition signals. In this study we examine patterns of vomeronasal type-1 receptor (V1R) evolution in the house mouse and related species within the genus Mus . We report the extent of gene repertoire turnover and conservation among species and clades, as well as the prevalence of positive selection on gene sequences across the V1R tree. By exploring the evolution of these receptors, we provide insight into the functional roles of receptor subtypes as well as the dynamics of gene family evolution. RESULTS: We generated transcriptomes from the vomeronasal organs of 5 Mus species, and produced high quality V1R repertoires for each species. We find that V1R clades in the house mouse and relatives exhibit distinct evolutionary trajectories. We identify putative species-specific gene expansions, including a large clade D expansion in the house mouse. While gene gains are abundant, we detect very few gene losses. We describe a novel V1R clade and highlight candidate receptors for future study. We find evidence for distinct evolutionary processes across different clades, from largescale turnover to highly conserved repertoires. Patterns of positive selection are similarly variable, as some clades exhibit abundant positive selection while others display high gene sequence conservation. Based on clade-level evolutionary patterns, we identify receptor families that are strong candidates for detecting social signals and predator cues. Our results reveal clades with receptors detecting female reproductive status are among the most conserved across species, suggesting an important role in V1R chemosensation. CONCLUSION: Analysis of clade-level evolution is critical for understanding species’ chemosensory adaptations. This study provides clear evidence that V1R clades are characterized by distinct evolutionary trajectories. As receptor evolution is shaped by ligand identity, these results provide a framework for examining the functional roles of receptors.

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Blakeslea trispora Photoreceptors: Identification and Functional Analysis

Applied and Environmental Microbiology ◽

10.1128/aem.02962-19 ◽

2020 ◽

Vol 86 (8) ◽

Author(s):

Wei Luo ◽

Chao Xue ◽

Yuzheng Zhao ◽

Huili Zhang ◽

Zhiming Rao ◽

...

Keyword(s):

Large Scale ◽

Binding Domain ◽

Site Directed Mutagenesis ◽

Flavin Mononucleotide ◽

Blakeslea Trispora ◽

Scale Production ◽

Bioinformatics Analyses ◽

Content Type ◽

Flavin Binding

ABSTRACT Blakeslea trispora is an industrial fungal species used for large-scale production of carotenoids. However, B. trispora light-regulated physiological processes, such as carotenoid biosynthesis and phototropism, are not fully understood. In this study, we isolated and characterized three photoreceptor genes, btwc-1a, btwc-1b, and btwc-1c, in B. trispora. Bioinformatics analyses of these genes and their protein sequences revealed that the functional domains (PAS/LOV [Per-ARNT-Sim/light-oxygen-voltage] domain and zinc finger structure) of the proteins have significant homology to those of other fungal blue-light regulator proteins expressed by Mucor circinelloides and Neurospora crassa. The photoreceptor proteins were synthesized by heterologous expression in Escherichia coli. The chromogenic groups consisting of flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) were detected to accompany BTWC-1 proteins by using high-performance liquid chromatography (HPLC) and fluorescence spectrometry, demonstrating that the proteins may be photosensitive. The absorbance changes of the purified BTWC-1 proteins seen under dark and light conditions indicated that they were light responsive and underwent a characteristic photocycle by light induction. Site-directed mutagenesis of the cysteine residual (Cys) in BTWC-1 did not affect the normal expression of the protein in E. coli but did lead to the loss of photocycle response, indicating that Cys represents a flavin-binding domain for photon detection. We then analyzed the functions of BTWC-1 proteins by complementing btwc-1a, btwc-1b, and btwc-1c into the counterpart knockout strains of M. circinelloides for each mcwc-1 gene. Transformation of the btwc-1a complement into mcwc-1a knockout strains restored the positive phototropism, while the addition of btwc-1c complement remedied the deficiency of carotene biosynthesis in the mcwc-1c knockout strains under conditions of illumination. These results indicate that btwc-1a and btwc-1c are involved in phototropism and light-inducible carotenogenesis. Thus, btwc-1 genes share a conserved flavin-binding domain and act as photoreceptors for control of different light transduction pathways in B. trispora. IMPORTANCE Studies have confirmed that light-regulated carotenogenesis is prevalent in filamentous fungi, especially in mucorales. However, few investigations have been done to understand photoinduced synthesis of carotenoids and related mechanisms in B. trispora, a well-known industrial microbial strains. In the present study, three photoreceptor genes in B. trispora were cloned, expressed, and characterized by bioinformatics and photoreception analyses, and then in vivo functional analyses of these genes were constructed in M. circinelloides. The results of this study will lead to a better understanding of photoreception and light-regulated carotenoid synthesis and other physiological responses in B. trispora.

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