Genome-wide identification of bHLH transcription factors and expression analysis under drought stress in Pseudoroegneria libanotica at germination.

The basic helix-loop-helix (bHLH) transcription factor family is the second largest in plants. bHLH transcription factor is not only universally involved in plant growth and metabolism, including photomorphogenesis, light signal transduction, and secondary metabolism, but also plays an important role in plant response to stress. However, the function of bHLH TFs in Pseudoroegneria species has not been studied yet. Pseudoroegneria (Nevski) Á. Löve is a perennial genus of the Triticeae. Pseudoroegneria species are mostly distributed in arid/semi-arid areas and they show good drought tolerance. In this study, we identified 152 PlbHLH TFs in Pseudoroegneria libanotica, which could be classified into 15 groups. Collinearity analysis indicates that 122 PlbHLH genes share homology with wbHLH genes in wheat, and it has lower homology with AtbHLH genes in Arabidopsis. Based on transcriptome profiling under an experiment with three PEG concentrations (0%, 10%, and 20%), 10 up-regulated genes and 11 down-regulated PlbHLH genes were screened. Among them, PlbHLH6, PlbHLH55 and PlbHLH64 as candidate genes may be the key genes related to drought tolerance response at germination, and they have been demonstrated to respond to drought, salt, oxidative, heat, and heavy metal stress in yeast. This study lays the foundation for an in-depth study of the biological roles of PlbHLHs in Pse. libanotica, and discovered new drought-tolerance candidate genes to enhance the genetic background of Triticeae crops. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-024-01433-w.

Roegneria yenchiana: A new species in the Triticeae (Poaceae) from the Hengduan Mountain region.

Roegneria yenchiana sp. nov. (Triticeae) is a new species collected from Shangri-la of Yunnan Province in China based on morphological, cytological, and molecular data. It is morphologically characterized by one spikelet per node, rectangular glums, awns flanked by two short mucros in lemmas, distinguished from other species of Roegneria. The genomic in situ hybridization results indicate that R. yenchiana is an allotetraploid, and its genomic constitution is StY. Phylogenetic analyses based on multiple loci suggested that R. yenchiana is closely related to Pseudoroegneria and Roegneria, and the Pseudoroegneria served as the maternal donors during its polyploid speciation.

A chromosome level genome assembly of Pseudoroegneria Libanotica reveals a key Kcs gene involves in the cuticular wax elongation for drought resistance.

BACKGROUND: The genus Pseudoroegneria (Nevski) Löve (Triticeae, Poaceae), whose genome symbol was designed as "St", accounts for more than 60% of perennial Triticeae species. The diploid species Psudoroegneria libanotica (2n = 14) contains the most ancient St genome, exhibited strong drought resistance, and was morphologically covered by cuticular wax on the aerial part. Therefore, the St-genome sequencing data could provide fundamental information for studies of genome evolution and reveal its mechanisms of cuticular wax and drought resistance. RESULTS: In this study, we reported the chromosome-level genome assembly for the St genome of Pse. libanotica, with a total size of 2.99 Gb. 46,369 protein-coding genes annotated and 71.62% was repeat sequences. Comparative analyses revealed that the genus Pseudoroegneria diverged during the middle and late Miocene. During this period, unique genes, gene family expansion, and contraction in Pse. libanotica were enriched in biotic and abiotic stresses, such as fatty acid biosynthesis which may greatly contribute to its drought adaption. Furthermore, we investigated genes associated with the cuticular wax formation and water deficit and found a new Kcs gene evm.TU.CTG175.54. It plays a critical role in the very long chain fatty acid (VLCFA) elongation from C18 to C26 in Pse. libanotica. The function needs more evidence to be verified. CONCLUSIONS: We sequenced and assembled the St genome in Triticeae and discovered a new KCS gene that plays a role in wax extension to cope with drought. Our study lays a foundation for the genome diversification of Triticeae species and deciphers cuticular wax formation genes involved in drought resistance.

Genome constitution and evolution of Elymus atratus (Poaceae: Triticeae) inferred from cytogenetic and phylogenetic analysis.

BACKGROUND: Elymus atratus (Nevski) Hand.-Mazz. is perennial hexaploid wheatgrass. It was assigned to the genus Elymus L. sensu stricto based on morphological characters. Its genome constitution has not been disentangled yet. OBJECTIVE: To identify the genome constitution and origin of E. atratus. METHODS: In this study, genomic in situ hybridization and fluorescence in situ hybridization, and phylogenetic analysis based on the Acc1, DMC1 and matK sequences were performed. RESULTS: Genomic in situ hybridization and fluorescence in situ hybridization results reveal that E. atratus 2n = 6x = 42 is composed of 14 St genome chromosomes, 14 H genome chromosomes, and 14 Y genome chromosomes including two H-Y type translocation chromosomes, suggesting that the genome formula of E. atratus is StStYYHH. The phylogenetic analysis based on Acc1 and DMC1 sequences not only shows that the Y genome originated in a separate diploid, but also suggests that Pseudoroegneria (St), Hordeum (H), and a diploid species with Y genome were the potential donors of E. atratus. Data from chloroplast DNA showed that the maternal donor of E. atratus contains the St genome. CONCLUSION: Elymus atratus is an allohexaploid species with StYH genome, which may have originated through the hybridization between an allotetraploid Roegneria (StY) species as the maternal donor and a diploid Hordeum (H) species as the paternal donor.

How the chemical structure of phosphoramides affect the fire retardancy and mechanical properties of polylactide?

Phosphoramides, as a kind of high-efficient fire retardants, have been designed in many structures and endowed exceptional fire retardancy to polylactide (PLA). However, due to ignorance of the structure-property correlation, the effect of phosphoramides' structure on the fire retardancy and mechanical properties of PLA is still unclear. Herein, a series of biobased phosphoramides (phosphoramide (V1), linear polyphosphoramide (V2) and hyperbranched polyphosphamide (V3)) were designed and incorporated into PLA, and the structural effect of phosphoramides on the fire-retardant and mechanical properties of PLA was deeply researched. Among three kinds of phosphoramides, the hyperbranched polyphosphoramide is more effective than the corresponding linear polyphosphoramide and phosphoramide in improving the fire-retardant and anti-dripping properties of PLA, and only linear polyphosphoramide shows a positive effect in the mechanical strength of PLA. This work provides a feasible strategy for creating mechanically robust and fire-retardant polymer composites by molecularly tailoring the structure of fire retardants and uncovering their structure-property relationship.

Cytogenetic and genomic characterization of a novel wheat-tetraploid Thinopyrum elongatum 1BS·1EL translocation line with stripe rust resistance.

Stripe rust, caused by Puccinia striiformis f. sp tritici (Pst), is a destructive wheat disease pathogen. Thinopyrum elongatum is a valuable germplasm including diploid, tetraploid, and decaploid with plenty of biotic and abiotic resistance. In a previous study, we generated a stripe rust resistance wheat-tetraploid Th. elongatum 1E/1D substitution line K17-841-1. To further apply the wild germplasm for wheat breeding, we selected and obtained a new homozygous wheat-tetraploid Th. elongatum translocation line T1BS·1EL using genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH), oligo-FISH-Painting, and the wheat 55K single nucleotide polymorphisms (SNPs) genotyping array. The T1BS·1EL is highly resistant to stripe rust at the seedling and adult stage. Pedigree and molecular marker analyses revealed that the resistance gene was located on chromosome arm 1EL of tetraploid Th. elongatum, tentatively named Yr1EL. Besides, we developed and validated 32 Simple Sequence Repeats (SSR) markers and two kompititive allele specific PCR (KASP) assays which were specific to tetraploid Th. elongatum chromosome arm 1EL to facilitate marker-assisted selection for alien 1EL stripe rust resistance breeding. This will help us explore and locate the stripe rust resistance gene mapping on the 1E chromosome and deploy it in the wheat breeding program.

Development, identification, and utilization of wheat-tetraploid Thinopyrum elongatum 4EL translocation lines resistant to stripe rust.

KEY MESSAGE: The new stripe rust resistance gene Yr4EL in tetraploid Th. elongatum was identified and transferred into common wheat via 4EL translocation lines. Tetraploid Thinopyrum elongatum is a valuable genetic resource for improving the resistance of wheat to diseases such as stripe rust, powdery mildew, and Fusarium head blight. We previously reported that chromosome 4E of the 4E (4D) substitution line carries all-stage stripe rust resistance genes. To optimize the utility of these genes in wheat breeding programs, we developed translocation lines by inducing chromosomal structural changes through 60Co-γ irradiation and developing monosomic substitution lines. In total, 53 plants with different 4E chromosomal structural changes were identified. Three homozygous translocation lines (T4DS·4EL, T5AL·4EL, and T3BL·4EL) and an addition translocation line (T5DS·4EL) were confirmed by the genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH), FISH-painting, and wheat 55 K SNP array analyses. These four translocation lines, which contained chromosome arm 4EL, exhibited high stripe rust resistance. Thus, a resistance gene (tentatively named Yr4EL) was localized to the chromosome arm 4EL of tetraploid Th. elongatum. For the application of marker-assisted selection (MAS), 32 simple sequence repeat (SSR) markers were developed, showing specific amplification on the chromosome arm 4EL and co-segregation with Yr4EL. Furthermore, the 4DS·4EL line could be selected as a good pre-breeding line that better agronomic traits than other translocation lines. We transferred Yr4EL into three wheat cultivars SM482, CM42, and SM51, and their progenies were all resistant to stripe rust, which can be used in future wheat resistance breeding programs.

Multi-omics comprehensive analyses of programmed cell death patterns to regulate the immune characteristics of head and neck squamous cell carcinoma.

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous cancer with high morbidity and mortality. Triggering the programmed cell death (PCD) to enhance the anti-tumor therapies is being applied in multiple cancers. However, the limited understanding of genetic heterogeneity in HNSCC severely hampers the clinical efficacy. We systematically analyzed 14 types of PCD in HNSCC from The Cancer Genome Atlas (TCGA). We utilized ssGSEA to calculate the PCD scores and classify patients into two clusters. Subsequently, we displayed the genomic alteration landscape to unravel the significant differences in copy number alterations and gene mutations. Furthermore, we calculated the IC50 values of targeted drugs to predict the differences in sensitivity. To identify the immune-related prognostic types, we comprehensively estimated the relationship between immune indicators and all prognostic PCD in three datasets (TCGA, GSE65858, GSE41613). Finally, 7 regulators were filtered. Subsequently, we integrated 10 machine learning algorithms and 101 algorithm combinations to test the clinical predictive efficacy. Using WGCNA as a basis, we built a weighted co-expression network to identify modules involved in the immune landscape with different colors. Meanwhile, our results indicated that blue and red modules containing crucial regulators closely related to the CD4+, CD8+ T cells, TMB or PD-L1. FCGR2A from blue module, CSF2, INHBA, and THBS1 from the red module were determined. After verifying in vivo experiments, FCGR2A was identified as hub gene. In conclusion, our findings suggest a potential role of PCD in HNSCC, offering new insights into effective immunotherapy and anti-tumor therapies in HNSCC.

Tung oil-based waterborne UV-curable coatings via cellulose nanofibril stabilized Pickering emulsions for self-healing and anticorrosion application.

In this study, waterborne UV-curable coatings with self-healing properties based on transesterification were prepared using renewable biomass resources for anti-corrosion application. Tung oil (TO)-based oligomer (TMHT) was synthesized through Diels-Alder reaction of TO with maleic anhydride, subsequent ring opening reaction with hydroxyethyl acrylate (HEA), and final neutralize reaction with triethylamine. A series of waterborne UV-curable coatings were prepared from cellulose nanofibrils (CNF) stabilized TMHT-based Pickering emulsions after drying and UV light-curing processes. It is suggested that CNF significantly improved the storage stability of Pickering emulsions. The obtained waterborne UV-curable coatings with CNF of 1-3 wt% exhibited remarking coating and mechanical performance (pencil hardness up to 5 H, adhesion up to 2 grade, flexibility of 2 mm, tensile strength up to 11.6 MPa, etc.), great transmittance (82.3 %-80.8 %) and great corrosion resistance (|Z|0.01Hz up to 5.4 × 106 Ω·cm2). Because of the presence of the dynamic ester bonds in TMHT, the coatings exhibited excellent self-healing performance (78.05 %-56.34 %) at 150 °C without catalyst and external force. More importantly, the |Z|0.01Hz of the self-healing coating was higher than that of the scratched coating, indicating that the self-healing performance could extend the service life of the coating in corrosion resistant application.

Pseudomonas aeruginosa regulator PvrA binds simultaneously to multiple pseudo-palindromic sites for efficient transcription activation.

Tetracycline repressor (TetR) family regulators (TFRs) are the largest group of DNA-binding transcription factors and are widely distributed in bacteria and archaea. TFRs play vital roles in controlling the expression of various genes and regulating diverse physiological processes. Recently, a TFR protein Pseudomonas virulence regulator A (PvrA), was identified from Pseudomonas aeruginosa as the transcriptional activator of genes involved in fatty acid utilization and bacterial virulence. Here, we show that PvrA can simultaneously bind to multiple pseudo-palindromic sites and upregulate the expression levels of target genes. Cryo-electron microscopy (cryo-EM) analysis indicates the simultaneous DNA recognition mechanism of PvrA and suggests that the bound DNA fragments consist of a distorted B-DNA double helix. The crystal structure and functional analysis of PvrA reveal a hinge region that secures the correct domain motion for recognition of the promiscuous promoter. Additionally, our results showed that mutations disrupting the regulatory hinge region have differential effects on biofilm formation and pyocyanin biosynthesis, resulting in attenuated bacterial virulence. Collectively, these findings will improve the understanding of the relationship between the structure and function of the TetR family and provide new insights into the mechanism of regulation of P. aeruginosa virulence.

Construction of heat stress regulation networks based on Illumina and SMRT sequencing data in potato.

Potato (Solanum tuberosum L.) is one of the most important tuber food crops in the world; however, the cultivated potatoes are susceptible to high temperature, by which potato production is adversely affected. Understanding the coping mechanism of potato to heat stress is essential to secure yield and expand adaptability under environmental conditions with rising temperature. However, the lack of heat-related information has significantly limited the identification and application of core genes. To gain deeper insights into heat tolerance genes, next-generation sequencing and single-molecule real-time sequencing were used to learn the transcriptional response of potato to heat stress and 13,159 differentially expressed genes (DEGs) were identified in this study. All DEGs were grouped into 12 clusters using the K-means clustering algorithm. Gene Ontology enrichment analysis revealed that they were involved in temperature signaling, phytohormone, and protein modification. Among them, there were 950 differentially expressed transcription factors (DETFs). According to the network analysis of DETFs at the sixth hour under heat stress, we found some genes that were previously reported to be associated with photoperiodic tuberization, StCO (CONSTANS), tuber formation, StBEL11 (BEL1-LIKE 11), and earliness in potato, StCDF1 (CYCLING DOF FACTOR 1) responding to temperature. Furthermore, we verified the relative expression levels using quantitative real-time polymerase chain reaction, and the results were consistent with the inferences from transcriptomes. In addition, there were 22,125 alternative splicing events and 2,048 long non-coding RNAs. The database and network established in this study will extend our understanding of potato response to heat stress. It ultimately provided valuable resources for molecular analysis of heat stress response in potato and cultivation of potato varieties with heat tolerance.

Short-term exposure to various ambient air pollutants and emergency department visits for cause-stable ischemic heart disease: a time-series study in Shanghai, China.

Studying the impact of local meteorological conditions and air pollution on cardiovascular disease is crucial for reducing the burden of cardiovascular disease. However, there have been few studies on the acute effects of various air pollutants on stable ischemic heart disease (SIHD), and the effects of these factors are not well defined and require further investigation. We performed a time-series study aimed at exploring the association between short-term exposure to various air pollutants and emergency department (ED) visits for SIHD during 2013-2020 in Baoshan District Renhe Hospital of Shanghai, China. The associations between air pollution (NO2, PM2.5, PM10, SO2 O3-8 h and CO) and ED visits were analyzed using quasi-Poisson regression. Subgroup and sensitivity analyses were conducted. From 2013 to 2020, a total of 18,241 ED visits for SIHD were recorded. Elevated PM2.5, PM10, NO2, SO2 and CO were significantly associated with increased ED visits for SIHD at lag (0, 5), lag 0, lag (0-4, 01-03), lag (0-3, 5, 01-03) and lag (3-5). When the concentration of O3-8 h was lower than the threshold recommended by the WHO, exposure to O3-8 h was associated with a slightly decreased risk of SIHD. Moreover, the relationship between different types of air pollution and the frequency of ED visits exhibited variations based on gender, age, and seasonality. This study suggests that short-term exposure to PM2.5, PM10, NO2, SO2 and CO might induce SIHD, especially in old females. Air pollution control measures should be encouraged to prevent the occurrence and development of SIHD.

Fungal co-expression network analyses identify pathogen gene modules associated with host insect invasion.

The broad host range fungal insect pathogen, Beauveria bassiana, has been commercialized as an alternative to chemical insecticides for pest control worldwide. B. bassiana represents a unique model system with which to examine host-pathogen interactions, and a wide range of genes and processes have been studied. However, significant aspects of virulence, particularly on the genomic scale, remain poorly studied. Here, we have combined available transcriptomes with three newly generated data sets for a combined total analysis of 76 deep-sequenced samples covering growth, development, stress responses, and infection during the life cycle of B. bassiana. Co-expression network analyses resulted in the identification of gene modules enriched during two critical stages of the infection process, namely (i) cuticle penetration and (ii) in vivo hyphal body (dimorphic transition) growth capable of avoiding innate and humoral immune defenses. These analyses identify unique signatures of metabolism, signaling, secondary metabolite production, host defense suppression, membrane reorganization, effector production, and secretion for each stage, including genetic regulators and epigenetic patterns. These data provide a comprehensive framework for understanding and probing fungal adaptations to its pathogenic life cycle and expand the candidate repertoire for continued dissection of the host-pathogen interaction. IMPORTANCE Insect fungal pathogens have evolved unique strategies for overcoming host structural and immunological defenses that span from the sclerotized cuticle to innate and humoral cellular responses. Two critical stages of the infection process involve (i) cuticle penetration and (ii) immune evasion within the insect hemocoel. A set of 76 global transcriptomic data for B. bassiana that include the cuticle penetration and hemocoel growth stages were analyzed for patterns (gene modules) of expression, yielding unique insights into these different life stages. These analyses integrate gene networks involved in fungal development, stress response and pathogenesis to further the systematic understanding of the global processes integral to the unique adaptation employed by fungal pathogens of insects.

Drivers of diversification in Linum (Linaceae) by means of chromosome evolution: correlations with biogeography, breeding system and habit.

BACKGROUND AND AIMS: Chromosome evolution leads to hybrid dysfunction and recombination patterns and has thus been proposed as a major driver of diversification in all branches of the tree of life, including flowering plants. In this study we used the genus Linum (flax species) to evaluate the effects of chromosomal evolution on diversification rates and on traits that are important for sexual reproduction. Linum is a useful study group because it has considerable reproductive polymorphism (heterostyly) and chromosomal variation (n = 6-36) and a complex pattern of biogeographical distribution. METHODS: We tested several traditional hypotheses of chromosomal evolution. We analysed changes in chromosome number across the phylogenetic tree (ChromEvol model) in combination with diversification rates (ChromoSSE model), biogeographical distribution, heterostyly and habit (ChromePlus model). KEY RESULTS: Chromosome number evolved across the Linum phylogeny from an estimated ancestral chromosome number of n = 9. While there were few apparent incidences of cladogenesis through chromosome evolution, we inferred up to five chromosomal speciation events. Chromosome evolution was not related to heterostyly but did show significant relationships with habit and geographical range. Polyploidy was negatively correlated with perennial habit, as expected from the relative commonness of perennial woodiness and absence of perennial clonality in the genus. The colonization of new areas was linked to genome rearrangements (polyploidy and dysploidy), which could be associated with speciation events during the colonization process. CONCLUSIONS: Chromosome evolution is a key trait in some clades of the Linum phylogeny. Chromosome evolution directly impacts speciation and indirectly influences biogeographical processes and important plant traits.

Chromosome-specific painting in Thinopyrum species using bulked oligonucleotides.

KEY MESSAGE: Chromosome-specific painting probes were developed to identify the individual chromosomes from 1 to 7E in Thinopyrum species and detect alien genetic material of the E genome in a wheat background. The E genome of Thinopyrum is closely related to the ABD genome of wheat (Triticum aestivum L.) and harbors genes conferring beneficial traits to wheat, including high yield, disease resistance, and unique end-use quality. Species of Thinopyrum vary from diploid (2n = 2x = 14) to decaploid (2n = 10x = 70), and chromosome structural variation and differentiation have arisen during polyploidization. To investigate the variation and evolution of the E genome, we developed a complete set of E genome-specific painting probes for identification of the individual chromosomes 1E to 7E based on the genome sequences of Th. elongatum (Host) D. R. Dewey and wheat. By using these new probes in oligonucleotide-based chromosome painting, we showed that Th. bessarabicum (PI 531711, EbEb) has a close genetic relationship with diploid Th. elongatum (EeEe), with five chromosomes (1E, 2E, 3E, 6E, and 7E) maintaining complete synteny in the two species except for a reciprocal translocation between 4 and 5Eb. All 14 pairs of chromosomes of tetraploid Th. elongatum have maintained complete synteny with those of diploid Th. elongatum (Thy14), but the two sets of E genomes have diverged. This study also demonstrated that the E genome-specific painting probes are useful for rapid and effective detection of the alien genetic material of E genome in wheat-Thinopyrum derived lines.

Cell detoxification of secondary metabolites by P4-ATPase-mediated vesicle transport.

Mechanisms for cellular detoxification of drug compounds are of significant interest in human health. Cyclosporine A (CsA) and tacrolimus (FK506) are widely known antifungal and immunosuppressive microbial natural products. However, both compounds can result in significant side effects when used as immunosuppressants. The insect pathogenic fungus Beauveria bassiana shows resistance to CsA and FK506. However, the mechanisms underlying the resistance have remained unknown. Here, we identify a P4-ATPase gene, BbCRPA, from the fungus, which confers resistance via a unique vesicle mediated transport pathway that targets the compounds into detoxifying vacuoles. Interestingly, the expression of BbCRPA in plants promotes resistance to the phytopathogenic fungus Verticillium dahliae via detoxification of the mycotoxin cinnamyl acetate using a similar pathway. Our data reveal a new function for a subclass of P4-ATPases in cell detoxification. The P4-ATPases conferred cross-species resistance can be exploited for plant disease control and human health protection.

Abscisic acid (ABA) alleviates cadmium toxicity by enhancing the adsorption of cadmium to root cell walls and inducing antioxidant defense system of Cosmos bipinnatus.

Cadmium (Cd) pollution is a global problem affecting soil ecology and plant growth. Abscisic acid (ABA) acts as a growth and stress hormone, regulates cell wall synthesis, and plays an important role in plant responses to stress. There are few studies on the mechanisms behind abscisic acid alleviation of cadmium stress in Cosmos bipinnatus, especially in regards to regulation of the root cell wall. This study examined the effects of different concentrations of abscisic acid at different concentrations of cadmium stress. Through adding 5 µmol/L and 30 µmol/L cadmium, followed by spraying 10 µmol/L and 40 µmol/L ABA in a hydroponic experiment, it was found that under two concentrations of cadmium stress, low concentration of ABA improved root cell wall polysaccharide, Cd, and uronic acid content. Especially in pectin, after the application of low concentration ABA, the cadmium concentration was significantly increased by 1.5 times and 1.2 times compared with the Cd concentration under Cd5 and Cd30 treatment alone, respectively. Fourier-Transform Infrared spectroscopy (FTIR) demonstrated that cell wall functional groups such as -OH and -COOH were increased with exposure to ABA. Additionally, the exogenous ABA also increased expression of three kinds of antioxidant enzymes and plant antioxidants. The results of this study suggest that ABA could reduce Cd stress by increasing Cd accumulation, promoting Cd adsorption on the root cell wall, and activating protective mechanisms. This result could help promote application of C. bipinnatus for phytostabilization of cadmium-contaminated soil.

Dynamic Translational Landscape Revealed by Genome-Wide Ribosome Profiling under Drought and Heat Stress in Potato.

The yield and quality of potatoes, an important staple crop, are seriously threatened by high temperature and drought stress. In order to deal with this adverse environment, plants have evolved a series of response mechanisms. However, the molecular mechanism of potato's response to environmental changes at the translational level is still unclear. In this study, we performed transcriptome- and ribosome-profiling assays with potato seedlings growing under normal, drought, and high-temperature conditions to reveal the dynamic translational landscapes for the first time. The translational efficiency was significantly affected by drought and heat stress in potato. A relatively high correlation (0.88 and 0.82 for drought and heat stress, respectively) of the fold changes of gene expression was observed between the transcriptional level and translational level globally based on the ribosome-profiling and RNA-seq data. However, only 41.58% and 27.69% of the different expressed genes were shared by transcription and translation in drought and heat stress, respectively, suggesting that the transcription or translation process can be changed independently. In total, the translational efficiency of 151 (83 and 68 for drought and heat, respectively) genes was significantly changed. In addition, sequence features, including GC content, sequence length, and normalized minimal free energy, significantly affected the translational efficiencies of genes. In addition, 28,490 upstream open reading frames (uORFs) were detected on 6463 genes, with an average of 4.4 uORFs per gene and a median length of 100 bp. These uORFs significantly affected the translational efficiency of downstream major open reading frames (mORFs). These results provide new information and directions for analyzing the molecular regulatory network of potato seedlings in response to drought and heat stress.

Development and Characterization of a Novel Wheat-Tetraploid Thinopyrum elongatum 6E (6D) Disomic Substitution Line with Stripe Rust Resistance at the Adult Stage.

Stripe rust, which is caused by Puccinia striiformis f. sp. tritici, is one of the most devastating foliar diseases of common wheat worldwide. Breeding new wheat varieties with durable resistance is the most effective way of controlling the disease. Tetraploid Thinopyrum elongatum (2n = 4x = 28, EEEE) carries a variety of genes conferring resistance to multiple diseases, including stripe rust, Fusarium head blight, and powdery mildew, which makes it a valuable tertiary genetic resource for enhancing wheat cultivar improvement. Here, a novel wheat-tetraploid Th. elongatum 6E (6D) disomic substitution line (K17-1065-4) was characterized using genomic in situ hybridization and fluorescence in situ hybridization chromosome painting analyses. The evaluation of disease responses revealed that K17-1065-4 is highly resistant to stripe rust at the adult stage. By analyzing the whole-genome sequence of diploid Th. elongatum, we detected 3382 specific SSR sequences on chromosome 6E. Sixty SSR markers were developed, and thirty-three of them can accurately trace chromosome 6E of tetraploid Th. elongatum, which were linked to the disease resistance gene(s) in the wheat genetic background. The molecular marker analysis indicated that 10 markers may be used to distinguish Th. elongatum from other wheat-related species. Thus, K17-1065-4 carrying the stripe rust resistance gene(s) is a novel germplasm useful for breeding disease-resistant wheat cultivars. The molecular markers developed in this study may facilitate the mapping of the stripe rust resistance gene on chromosome 6E of tetraploid Th. elongatum.

Precisely mapping a major QTL for grain weight on chromosome 5B of the founder parent Chuanmai42 in the wheat-growing region of southwestern China.

KEY MESSAGE: QTgw.saas-5B was validated as a major thousand-grain weight-related QTL in a founder parent used for wheat breeding and then precisely mapped to a 0.6 cM interval. Increasing the thousand-grain weight (TGW) is considered to be one of the most important ways to improve yield, which is a core objective among wheat breeders. Chuanmai42, which is a wheat cultivar with high TGW and a high and stable yield, is a parent of more than 30 new varieties grown in southwestern China. In this study, a Chuanmai42-derived recombinant inbred line (RIL) population was used to dissect the genetic basis of TGW. A major QTL (QTgw.saas-5B) mapped to the Xgwm213-Xgwm540 interval on chromosome 5B of Chuanmai42 explained up to 20% of the phenotypic variation. Using 71 recombinants with a recombination in the QTgw.saas-5B interval identified from a secondary RIL population comprising 1818 lines constructed by crossing the QTgw.saas-5B near-isogenic line with the recurrent parent Chuannong16, QTgw.saas-5B was delimited to a 0.6 cM interval, corresponding to a 21.83 Mb physical interval in the Chinese Spring genome. These findings provide the foundation for QTgw.saas-5B cloning and its use in molecular marker-assisted breeding.