Identification, Characterization, and Expression Profile Analysis of the mTERF Gene Family and Its Role in the Response to Abiotic Stress in Barley (Hordeum vulgare L.)

Preharvest Sprouting in Quinoa: A New Screening Method Adapted to Panicles and GWAS Components

The introduction of quinoa into new growing regions and environments is of interest to farmers, consumers, and stakeholders around the world. Many plant breeding programs have already started to adapt quinoa to the environmental and agronomic conditions of their local fields. Formal quinoa breeding efforts in Washington State started in 2010, led by Professor Kevin Murphy out of Washington State University. Preharvest sprouting appeared as the primary obstacle to increased production in the coastal regions of the Pacific Northwest. Preharvest sprouting (PHS) is the undesirable sprouting of seeds that occurs before harvest, is triggered by rain or humid conditions, and is responsible for yield losses and lower nutrition in cereal grains. PHS has been extensively studied in wheat, barley, and rice, but there are limited reports for quinoa, partly because it has only recently emerged as a problem. This study aimed to better understand PHS in quinoa by adapting a PHS screening method commonly used in cereals. This involved carrying out panicle-wetting tests and developing a scoring scale specific for panicles to quantify sprouting. Assessment of the trait was performed in a diversity panel (N = 336), and the resulting phenotypes were used to create PHS tolerance rankings and undertake a GWAS analysis (n = 279). Our findings indicate that PHS occurred at varying degrees across a subset of the quinoa germplasm tested and that it is possible to access PHS tolerance from natural sources. Ultimately, these genotypes can be used as parental lines in future breeding programs aiming to incorporate tolerance to PHS.

The barley DIR gene family: An expanded gene family that is involved in stress responses

Gene family expansion plays a central role in adaptive divergence and, ultimately, speciation is influenced by phenotypic diversity in different environments. Barley (Hordeum vulgare) is the fourth most important cereal crop in the world and is used for brewing purposes, animal feed, and human food. Systematic characterization of expanded gene families is instrumental in the research of the evolutionary history of barley and understanding of the molecular function of their gene products. A total of 31,750 conserved orthologous groups (OGs) were identified using eight genomes/subgenomes, of which 1,113 and 6,739 were rapidly expanded and contracted OGs in barley, respectively. Five expanded OGs containing 20 barley dirigent genes (HvDIRs) were identified. HvDIRs from the same OG were phylogenetically clustered with similar gene structure and domain organization. In particular, 7 and 5 HvDIRs from OG0000960 and OG0001516, respectively, contributed greatly to the expansion of the DIR-c subfamily. Tandem duplication was the driving force for the expansion of the barley DIR gene family. Nucleotide diversity and haplotype network analysis revealed that the expanded HvDIRs experienced severe bottleneck events during barley domestication, and can thus be considered as potential domestication-related candidate genes. The expression profile and co-expression network analysis revealed the critical roles of the expanded HvDIRs in various biological processes, especially in stress responses. HvDIR18, HvDIR19, and HvDIR63 could serve as excellent candidates for further functional genomics studies to improve the production of barley products. Our study revealed that the HvDIR family was significantly expanded in barley and might be involved in different developmental processes and stress responses. Thus, besides providing a framework for future functional genomics and metabolomics studies, this study also identified HvDIRs as candidates for use in improving barley crop resistance to biotic and abiotic stresses.

Genome-Wide Identification, Evolution and Expressional Analysis of OSCA Gene Family in Barley (Hordeum vulgare L.)

The hyperosmolality-gated calcium-permeable channel gene family (OSCA) is one kind of conserved osmosensors, playing a crucial role in maintaining ion and water homeostasis and protecting cellular stability from the damage of hypertonic stress. Although it has been systematically characterized in diverse plants, it is necessary to explore the role of the OSCA family in barley, especially its importance in regulating abiotic stress response. In this study, a total of 13 OSCA genes (HvOSCAs) were identified in barley through an in silico genome search method, which were clustered into 4 clades based on phylogenetic relationships with members in the same clade showing similar protein structures and conserved motif compositions. These HvOSCAs had many cis-regulatory elements related to various abiotic stress, such as MBS and ARE, indicating their potential roles in abiotic stress regulation. Furthermore, their expression patterns were systematically detected under diverse stresses using RNA-seq data and qRT-PCR methods. All of these 13 HvOSCAs were significantly induced by drought, cold, salt and ABA treatment, demonstrating their functions in osmotic regulation. Finally, the genetic variations of the HvOSCAs were investigated using the re-sequencing data, and their nucleotide diversity in wild barley and landrace populations were 0.4966 × 10-3 and 0.391 × 10-3, respectively, indicating that a genetic bottleneck has occurred in the OSCA family during the barley evolution process. This study evaluated the genomic organization, evolutionary relationship and genetic expression of the OSCA family in barley, which not only provides potential candidates for further functional genomic study, but also contributes to genetically improving stress tolerance in barley and other crops.

BGFD: an integrated multi-omics database of barley gene families

BACKGROUND

A gene family comprises a group of genes with similar functional domains that play various roles in plant growth, development, and responses to environmental stimuli. Barley (Hordeum vulgare L.) is the fourth most cultivated cereal crop worldwide, and it is an important model species for genetic studies. Systematic identification and annotation of gene families are key for studies of molecular function and evolutionary history.

RESULTS

We constructed a multi-omics database containing 5593 genes of 77 gene families called the Barley Gene Family Database (BGFD: http://barleygfdb.com ). BGFD is a free, user-friendly, and web-accessible platform that provides data on barley family genes. BGFD provides intuitive visual displays to facilitate studies of the physicochemical properties, gene structure, phylogenetic relationships, and motif organization of genes. Massive multi-omics datasets have been acquired and processed to generate an atlas of expression pattern profiles and genetic variation in BGFD. The platform offers several practical toolkits to conduct searches, browse, and employ BLAST functions, and the data are downloadable.

CONCLUSIONS

BGFD will aid research on the domestication and adaptive evolution of barley; it will also facilitate the screening of candidate genes and exploration of important agronomic traits in barley.

CCCH Zinc finger genes in Barley: genome-wide identification, evolution, expression and haplotype analysis

BACKGROUND

CCCH transcription factors are important zinc finger transcription factors involved in the response to biotic and abiotic stress and physiological and developmental processes. Barley (Hordeum vulgare) is an agriculturally important cereal crop with multiple uses, such as brewing production, animal feed, and human food. The identification and assessment of new functional genes are important for the molecular breeding of barley.

RESULTS

In this study, a total of 53 protein-encoding CCCH genes unevenly dispersed on seven different chromosomes were identified in barley. Phylogenetic analysis categorized the barley CCCH genes (HvC3Hs) into eleven subfamilies according to their distinct features, and this classification was supported by intron-exon structure and conserved motif analysis. Both segmental and tandem duplication contributed to the expansion of CCCH gene family in barley. Genetic variation of HvC3Hs was characterized using publicly available exome-capture sequencing datasets. Clear genetic divergence was observed between wild and landrace barley populations in HvC3H genes. For most HvC3Hs, nucleotide diversity and the number of haplotype polymorphisms decreased during barley domestication. Furthermore, the HvC3H genes displayed distinct expression profiles for different developmental processes and in response to various types of stresses. The HvC3H1, HvC3H2 and HvC3H13 of arginine-rich tandem CCCH zinc finger (RR-TZF) genes were significantly induced by multiple types of abiotic stress and/or phytohormone treatment, which might make them as excellent targets for the molecular breeding of barley.

CONCLUSIONS

Overall, our study provides a comprehensive characterization of barley CCCH transcription factors, their diversity, and their biological functions.