Pathogenesis-related protein-4 (PR-4) gene family in Qingke (Hordeum vulgare L. var. nudum): genome-wide identification, structural analysis and expression profile under stresses.

BACKGROUND: Pathogenesis-related (PR) proteins are active participants of plant defense against biotic and abiotic stresses. The PR-4 family features a Barwin domain at the C-terminus, which endows the host plant with disease resistance. However, comprehensive analysis of PR-4 genes is still lacking in Qingke (Hordeum vulgare L. var. nudum). METHODS AND RESULTS: Herein, a total of four PR-4 genes were identified from the genome of Qingke through HMM profiling. Devoid of the chitin-binding domain, these 4 proteins were grouped as class II PR-4s. Phylogenic analysis revealed that 127 PR-4s from 47 species were clustered into 3 major groups, among which the four Qingke PR-4s were claded into group I. Analysis of gene structure demonstrated that no intron was found in 3 out of the 4 Qingke PR-4s, and HOVUSG0928500 was the only gene contained one intron. An array of cis-acting motifs were detected in promoters of Qingke PR-4 genes, including elements associated with hormone response, light response, stress response, growth and development processes and binding sites of transcription factors, implying their diverse role. Expression profiling confirmed that Qingke PR-4s were involved in defense response against drought, cold and powdery mildews infection, and transcription of HOVUSG1974300 and HOVUSG5705400 was differentially regulated by MeJA and SA. CONCLUSION: Findings of the study provided insights into the genetic basis of the PR-4 family genes, and would promote further investigation on protein function and utilization.

Single-molecule real-time sequencing of the full-length transcriptome of purple garlic (Allium sativum L. cv. Leduzipi) and identification of serine O-acetyltransferase family proteins involved in cysteine biosynthesis.

BACKGROUND: Garlic (Allium sativum L.), whose bioactive components are mainly organosulfur compounds (OSCs), is a herbaceous perennial widely consumed as a green vegetable and a condiment. Yet, the metabolic enzymes involved in the biosynthesis of OSCs are not identified in garlic. RESULTS: Here, a full-length transcriptome of purple garlic was generated via PacBio and Illumina sequencing, to characterize the garlic transcriptome and identify key proteins mediating the biosynthesis of OSCs. Overall, 22.56 Gb of clean data were generated, resulting in 454 698 circular consensus sequence (CCS) reads, of which 83.4% (379 206) were identified as being full-length non-chimeric reads - their further transcript clustering facilitated identification of 36 571 high-quality consensus reads. Once corrected, their genome-wide mapping revealed that 6140 reads were novel isoforms of known genes, and 2186 reads were novel isoforms from novel genes. We detected 1677 alternative splicing events, finding 2902 genes possessing either two or more poly(A) sites. Given the importance of serine O-acetyltransferase (SERAT) in cysteine biosynthesis, we investigated the five SERAT homologs in garlic. Phylogenetic analysis revealed a three-tier classification of SERAT proteins, each featuring a serine acetyltransferase domain (N-terminal) and one or two hexapeptide transferase motifs. Template-based modeling showed that garlic SERATs shared a common homo-trimeric structure with homologs from bacteria and other plants. The residues responsible for substrate recognition and catalysis were highly conserved, implying a similar reaction mechanism. In profiling the five SERAT genes' transcript levels, their expression pattern varied significantly among different tissues. CONCLUSION: This study's findings deepen our knowledge of SERAT proteins, and provide timely genetic resources that could advance future exploration into garlic's genetic improvement and breeding. © 2021 Society of Chemical Industry.

Sequencing and comparative analysis of the chloroplast genome of Ribes odoratum provide insights for marker development and phylogenetics in Ribes.

Ribes odoratum, commonly known as clove currant, is a perennial deciduous shrub noted for its long-lasting fragrant flowers and edible fruits. Owing to its ornamental values, this species has been widely used in city gardening and urban landscaping. Here, the complete cp genome of R. odoratum was de novo assembled for the first time. The plastome is 157,152 bp in length, with a GC content of 38.2%. The cp genome featured a typical quadripartite structure, consisting of a pair of inverted repeat regions of 25,961 bp, separated by a large single copy region of 86,896 bp, and a small single copy region of 18,333 bp. A total of 131 genes were annotated in the plastome, including 86 protein coding genes, 37 tRNA genes, and 8 rRNA genes. 56 SSRs were identified, among which, 82.35% were located in the intergenic regions. A strong A/T bias in base composition was observed in these cpSSRs. In addition, 49 repeats of different sizes and types were also found in the plastome. Through comparison, seven divergence hotspots were identified between the cp genomes of R. odoratum and R. fasciculatum var. chinense. Sequences of these divergent regions could be developed as potential markers for species delimitation in further studies. We re-investigated the relationship aomong 32 Saxifragales species through plastome-based phylogenywhich revealed that R. odoratum as a sister of R. fasciculatum var. chinense. Thus, our study provides genomic resources and valuable reference for marker development and phylogenomics in Ribes. SUPPLEMENTARY INFORMATION: The online version of this article (10.1007/s12298-021-00932-4) contains supplementary material, which is available to authorized users.

The complete plastome of Sorbaria kirilowii: genome structure, comparative analysis, and phylogenetic implications.

Sorbaria kirilowii is a deciduous perennial admired for its showy white blossoms. Though of importance for horticultural purposes, the plastomic study concerning this species is still lacking. Here, the plastome of S. kirilowii was de novo assembled using the high-throughput sequencing data. The complete plastome assembly of S. kirilowii was 160,810 bp in length, with a GC content of 36.03%. It featured a typical quadripartite structure, containing a pair of inverted repeats (IRs; 26,338 bp) separated by a large single-copy (LSC; 88,762 bp) and a small single-copy (SSC, 19,372 bp). In total, 132 genes were annotated in the plastome, including 87 protein-coding genes, 8 rRNA genes, and 37 tRNA genes. Furthermore, 63 SSRs, most of which were AT-rich, were identified in the cp genome of S. kirilowii. 71.7% of the cpSSRs were shown to be located in the intergenic regions. In addition, 49 repeats of varying sizes and types were also identified in the plastome. Through comparison, eight divergence hotspots were identified between the plastome of S. kirilowii and S. sorbifolia var. stellipila. These variable regions could potentially be developed into molecular markers for species delimitation or phylogenetics in future studies. We re-investigated the relationship among 17 Rosaceae species using the plastomic sequences, and S. kirilowii was shown to be a sister to S. sorbifolia var. stellipila. Overall, this study provides plastomic resources which could facilitate marker development and phylogenomics of Rosaceae.

Genome-wide analysis of pathogenesis-related protein-1 (PR-1) genes from Qingke (Hordeum vulgare L. var. nudum) reveals their roles in stress responses.

Proteins that are pathogenesis-related 1 (PR-1) can accumulate to high levels when plants employ defenses, being major participants in processes critical for stress responses as well as development of many species. Yet we still lack information concerning PR-1 family members in Qingke plants (Hordeum vulgare L. var. nudum). In this work, we distinguished 20 PR-1s from the Qingke genome whose encoded proteins often featured at the N-terminus a signal peptide; all 20 PR-1s were predicted to localize either periplasmically or extracellularly. The CAP domain was confirmed as being highly conserved in all these PR-1s. Phylogeny-based inference revealed that PR-1 proteins clustered into four major clades, with the majority of Qingke PR-1s distributed in clade I (17 out 20), and the other 3 distributed in clade II. Gene structure analysis showed that 16 PR-1s did not contain any introns, whereas the other four had 1-4 introns. We identified a variety of motifs that are cis-acting in the promoter regions of PR-1s; these included those potentially involved in Qingke's light response, hormonal and stress responses, circadian control and regulation of development and growth, in addition to sites where transcription factors bind to. Expression analysis uncovered several members of PR-1 genes that were strongly and rapidly induced by powdery mildew infection, phytohormones, and cold stimulus. Altogether, our study's findings enhance what is known about genetic features of PR-1 family members in H. vulgare plants, especially Qingke, and could thereby facilitate further exploration aiming to elucidate the functioning of these proteins.

Whole-genome sequencing and evolutionary analysis of the wild edible mushroom, Morchella eohespera.

Morels (Morchella, Ascomycota) are an extremely desired group of edible mushrooms with worldwide distribution. Morchella eohespera is a typical black morel species, belonging to the Elata clade of Morchella species. The biological and genetic studies of this mushroom are rare, largely hindering the studies of molecular breeding and evolutionary aspects. In this study, we performed de novo sequencing and assembly of the M. eohespera strain m200 genome using the third-generation nanopore sequencing platform. The whole-genome size of M. eohespera was 53.81 Mb with a contig N50 of 1.93 Mb, and the GC content was 47.70%. A total of 9,189 protein-coding genes were annotated. Molecular dating showed that M. eohespera differentiated from its relative M. conica at ~19.03 Mya (million years ago) in Burdigalian. Evolutionary analysis showed that 657 gene families were contracted and 244 gene families expanded in M. eohespera versus the related morel species. The non-coding RNA prediction results showed that there were 336 tRNAs, 76 rRNAs, and 45 snRNAs in the M. eohespera genome. Interestingly, there was a high degree of repetition (20.93%) in the M. eohespera genome, and the sizes of long interspersed nuclear elements, short interspersed nuclear elements, and long terminal repeats were 0.83 Mb, 0.009 Mb, and 4.56 Mb, respectively. Additionally, selection pressure analysis identified that a total of 492 genes in the M. eohespera genome have undergone signatures of positive selection. The results of this study provide new insights into the genome evolution of M. eohespera and lay the foundation for in-depth research into the molecular biology of the genus Morchella in the future.

Change of geographic distributions of the genus Morchella species responding to climate oscillations in East Asia.

Morchella is a rare macrofungi taxon with high medicinal and edible values. Influenced by recent climate oscillations and human activities, habitat fragmentation of this genus has been critical, leading to a rapid decline of the resource of Morchella. It is thus urgent to preserve Morchella species. Based on maximum entropy model (MaxEnt), and 102 geographic distribution records of Morchella species with 10 environmental factors, we simulated the changes of potential geographic distributions under the climatic conditions of the last glacial maximum (LGM), last interglacial (LIG), in contemporary period and future (2050, 2070). We further analyzed the potential changes of geographic distributions of Morchella species in East Asia under climate change and formulated the effective conservation strategies for Morchella. The results showed that the dominant environmental factors affecting the geographic distributions of Morchella species were mean temperature of coldest quarter, annual precipitation, elevation and temperature annual range, with the mean temperature of coldest quarter having the greatest contribution. Results of the species distribution models showed that the highly suitable regions for Morchella species were mainly distributed in parts of western China under contemporary period. From the LIG to LGM and then the current to the future period, the total suitable regions of Morchella species showed a trend of firstly decrease and then increase, while the highly suitable regions showed similar change with the total suitable regions. At present, there is an urgent need to conduct in situ conservation for the resources of Morchella species in highly suitable regions in western China, and to carry out ex situ conservation in the marginal ranges of highly suitable regions and moderately suitable regions of Shaanxi, Hebei, Shandong, and other regions in China.

DNA Barcoding and Species Classification of Morchella.

True morels (Morchella) are a well-known edible fungi, with economically and medicinally important values. However, molecular identification and species taxonomy of the genus Morchella have long been controversial, due to numerous intermediate morphologies among species. In this study, we determined the identification efficiency of DNA barcoding and species classification of 260 individuals from 45 Morchella species, on the basis of multiple nuclear DNA markers. DNA barcoding analysis showed that the individual DNA fragment has a lower resolution of species identification than that of combined multiple DNA markers. ITS showed the highest level of species discrimination among the individual genetic markers. Interestingly, the combined DNA markers significantly increased the resolution of species identification. A combination of four DNA genes (EF1-α, RPB1, RPB2 and ITS) showed a higher species delimitation than that any combination of two or three markers. Phylogenetic analysis suggested that the species in genus Morchella could have been divided into two large genetic clades, the Elata Clade and Esculenta Clade lineages. The two lineages divided approximately 133.11 Mya [95% HPD interval: 82.77-197.95] in the early Cretaceous period. However, some phylogenetic species of Morchella showed inconsistent evolutionary relationships with the traditional morphological classifications, which may have resulted from incomplete lineage sorting and/or introgressive hybridization among species. These findings demonstrate that the interspecific gene introgression may have affected the species identification of true morels, and that the combined DNA markers significantly improve the resolution of species discrimination.

Genome-wide analysis of the Thaumatin-like gene family in Qingke (Hordeum vulgare L. var. nudum) uncovers candidates involved in plant defense against biotic and abiotic stresses.

Thaumatin-like proteins (TLPs) participate in the defense responses of plants as well as their growth and development processes, including seed germination. Yet the functioning of TLP family genes, in addition to key details of their encoded protein products, has not been thoroughly investigated for Qingke (Hordeum vulgare L. var. nudum). Here, a total of 36 TLP genes were identified in the genome of Qingke via HMM profiling. Of them, 25 TLPs contained a signal peptide at the N-terminus, with most proteins predicted to localize in the cytoplasm or outer membrane. Sequence alignment and motif analysis revealed that the five REDDD residues required for ß-1,3-glucanase activity were conserved in 21 of the 36 Qingke TLPs. Phylogenetically, the TLPs in plants are clustered in 10 major groups. Our analysis of gene structure did not detect an intron in 15 Qingke TLPs whereas the other 21 did contain 1-7 introns. A diverse set of cis-acting motifs were found in the promoters of the 36 TLPs, including elements related to light, hormone, and stress responses, growth and development, circadian control, and binding sites of transcription factors, thus suggesting a multifaceted role of TLPs in Qingke. Expression analyses revealed the potential involvement of TLPs in plant defense against biotic and abiotic stresses. Taken together, the findings of this study deepen our understanding of the TLP family genes in Qingke, a staple food item in Tibet, which could strengthen future investigations of protein function in barley and its improved genetic engineering.

Maximum Entropy Modeling the Distribution Area of Morchella Dill. ex Pers. Species in China under Changing Climate.

Morchella is a kind of precious edible, medicinal fungi with a series of important effects, including anti-tumor and anti-oxidation effects. Based on the data of 18 environmental variables and the distribution sites of wild Morchella species, this study used a maximum entropy (MaxEnt) model to predict the changes in the geographic distribution of Morchella species in different historical periods (the Last Glacial Maximum (LGM), Mid Holocene (MH), current, 2050s and 2070s). The results revealed that the area under the curve (AUC) values of the receiver operating characteristic curves of different periods were all relatively high (>0.83), indicating that the results of the maximum entropy model are good. Species distribution modeling showed that the major factors influencing the geographical distribution of Morchella species were the precipitation of the driest quarter (Bio17), elevation, the mean temperature of the coldest quarter (Bio11) and the annual mean temperature (Bio1). The simulation of geographic distribution suggested that the current suitable habitat of Morchella was mainly located in Yunnan, Sichuan, Gansu, Shaanxi, Xinjiang Uygur Autonomous Region (XUAR) and other provinces in China. Compared with current times, the suitable area in Northwest and Northeast China decreased in the LGM and MH periods. As for the future periods, the suitable habitats all increased under the different scenarios compared with those in contemporary times, showing a trend of expansion to Northeast and Northwest China. These results could provide a theoretical basis for the protection, rational exploitation and utilization of wild Morchella resources under scenarios of climate change.

Characterization of the complete mitochondrial genome of Morchella eohespera.

Morchella eohespera Beug, Voitk & O'Donnell is a typical black morel species. In this study, using the Nanopore sequencing platform, we characterized its whole mitochondrial (mt) genome sequence. Mt genome of M. eohespera is composed of circular DNA molecules of 243,963 bp, which encoded 102 protein-coding genes (PCGs), two ribosomal RNA genes (rRNA), and 31 transfer RNA (tRNA) genes. The base composition of M. eohespera mitogenome is as follows: A (30.40%), T (29.30%), G (20.8%), and C (19.5%). The phylogenetic analysis suggested that M. eohespera was closely related to the congeneric M. importuna.

The complete nucleotide molecular sequence of plastid genome of Zanthoxylum armatum (Rutaceae).

Zanthoxylum armatum DC. (Rutaceae) is a shrub and/or tree species with the important medicinal and economic values. In this study, the plastid genome of Z. armatum was characterized by Illumina Hiseq 2500 sequencing platform. In total, the plastid genome is 158,557 bp in length, and comprises a large single copy region of 85,752 bp, a small single copy region of 17,605 bp, and two inverted repeat regions of 27,600 bp. The complete plastid genome contains 87 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. Phylogenetic analysis suggested that Z. armatum and the congeneric Z. simulans clustered into an evolutionary clade with the high support.

Development of Resistance in Escherichia coli ATCC25922 under Exposure of Sub-Inhibitory Concentration of Olaquindox.

Quinoxaline1,4-di-N-oxides (QdNOs) are a class of important antibacterial drugs of veterinary use, of which the drug resistance mechanism has not yet been clearly explained. This study investigated the molecular mechanism of development of resistance in Escherichia coli (E. coli) under the pressure of sub-inhibitory concentration (sub-MIC) of olaquindox (OLA), a representative QdNOs drug. In vitro challenge of E. coli with 1/100× MIC to 1/2× MIC of OLA showed that the bacteria needed a longer time to develop resistance and could only achieve low to moderate levels of resistance as well as form weak biofilms. The transcriptomic and genomic profiles of the resistant E. coli induced by sub-MIC of OLA demonstrated that genes involved in tricarboxylic acid cycle, oxidation-reduction process, biofilm formation, and efflux pumps were up-regulated, while genes involved in DNA repair and outer membrane porin were down-regulated. Mutation rates were significantly increased in the sub-MIC OLA-treated bacteria and the mutated genes were mainly involved in the oxidation-reduction process, DNA repair, and replication. The SNPs were found in degQ, ks71A, vgrG, bigA, cusA, and DR76-4702 genes, which were covered in both transcriptomic and genomic profiles. This study provides new insights into the resistance mechanism of QdNOs and increases the current data pertaining to the development of bacterial resistance under the stress of antibacterials at sub-MIC concentrations.

Using ELM-based weighted probabilistic model in the classification of synchronous EEG BCI.

Extreme learning machine (ELM) is an effective machine learning technique with simple theory and fast implementation, which has gained increasing interest from various research fields recently. A new method that combines ELM with probabilistic model method is proposed in this paper to classify the electroencephalography (EEG) signals in synchronous brain-computer interface (BCI) system. In the proposed method, the softmax function is used to convert the ELM output to classification probability. The Chernoff error bound, deduced from the Bayesian probabilistic model in the training process, is adopted as the weight to take the discriminant process. Since the proposed method makes use of the knowledge from all preceding training datasets, its discriminating performance improves accumulatively. In the test experiments based on the datasets from BCI competitions, the proposed method is compared with other classification methods, including the linear discriminant analysis, support vector machine, ELM and weighted probabilistic model methods. For comparison, the mutual information, classification accuracy and information transfer rate are considered as the evaluation indicators for these classifiers. The results demonstrate that our method shows competitive performance against other methods.

Quinoxaline 1,4-di-N-Oxides: Biological Activities and Mechanisms of Actions.

Quinoxaline 1,4-di-N-oxides (QdNOs) have manifold biological properties, including antimicrobial, antitumoral, antitrypanosomal and antiinflammatory/antioxidant activities. These diverse activities endow them broad applications and prospects in human and veterinary medicines. As QdNOs arouse widespread interest, the evaluation of their medicinal chemistry is still in progress. In the meantime, adverse effects have been reported in some of the QdNO derivatives. For example, genotoxicity and bacterial resistance have been found in QdNO antibacterial growth promoters, conferring urgent need for discovery of new QdNO drugs. However, the modes of actions of QdNOs are not fully understood, hindering the development and innovation of these promising compounds. Here, QdNOs are categorized based on the activities and usages, among which the antimicrobial activities are consist of antibacterial, antimycobacterial and anticandida activities, and the antiprotozoal activities include antitrypanosomal, antimalarial, antitrichomonas, and antiamoebic activities. The structure-activity relationship and the mode of actions of each type of activity of QdNOs are summarized, and the toxicity and the underlying mechanisms are also discussed, providing insight for the future research and development of these fascinating compounds.