QTL mapping for the flag leaf-related traits using RILs derived from Trititrigia germplasm line SN304 and wheat cultivar Yannong15 in multiple environments.

BACKGROUND: Developing and enriching genetic resources plays important role in the crop improvement. The flag leaf affects plant architecture and contributes to the grain yield of wheat (Triticum aestivum L.). The genetic improvement of flag leaf traits faces problems such as a limited genetic basis. Among the various genetic resources of wheat, Thinopyrum intermedium has been utilized as a valuable resource in genetic improvement due to its disease resistance, large spikes, large leaves, and multiple flowers. In this study, a recombinant inbred line (RIL) population was derived from common wheat Yannong15 and wheat-Th. intermedium introgression line SN304 was used to identify the quantitative trait loci (QTL) for flag leaf-related traits. RESULTS: QTL mapping was performed for flag leaf length (FLL), flag leaf width (FLW) and flag leaf area (FLA). A total of 77 QTLs were detected, and among these, 51 QTLs with positive alleles were contributed by SN304. Fourteen major QTLs for flag leaf traits were detected on chromosomes 2B, 3B, 4B, and 2D. Additionally, 28 QTLs and 8 QTLs for flag leaf-related traits were detected in low-phosphorus and drought environments, respectively. Based on major QTLs of positive alleles from SN304, we identified a pair of double-ended anchor primers mapped on chromosome 2B and amplified a specific band of Th. intermedium in SN304. Moreover, there was a major colocated QTL on chromosome 2B, called QFll/Flw/Fla-2B, which was delimited to a physical interval of approximately 2.9 Mb and contained 20 candidate genes. Through gene sequence and expression analysis, four candidate genes associated with flag leaf formation and growth in the QTL interval were identified. CONCLUSION: These results promote the fine mapping of QFll/Flw/Fla-2B, which have pleiotropic effects, and will facilitate the identification of candidate genes for flag leaf-related traits. Additionally, this work provides a theoretical basis for the application of Th. intermedium in wheat breeding.

Genome Analysis of Thinopyrum intermedium and Its Potential Progenitor Species Using Oligo-FISH.

The genome composition of intermediate wheatgrass (IWG) is complex and continues to be a subject of investigation. In this study, molecular cytogenetics were used to investigate the karyotype composition of Th. intermedium and its relative diploid species. St2-80 developed from Pseudowroegneria strigose and pDb12H developed from Dasypyrum breviaristatum were used as probes in fluorescence in situ hybridization (FISH) to classify the chromosomes of Th. intermedium into three groups, expressed as JvsJvsJrJrStSt. A combined multiplex oligonucleotide probe, including pSc119.2-1, (GAA)10, AFA-3, AFA-4, pAs1-1, Pas1-3, pAs1-4, and pAs1-6, was used to establish the FISH karyotype of ten accessions of Th. intermedium. Variability among and within the studied accessions of intermediate wheatgrass was observed in their FISH patterns. Results of this study led to the conclusions that Jvs had largely been contributed from Da. breviaristatum, but not the present-day Da. villosum; IWG had only one J genome, Jr, which was related to either Th. elongatum or Th. bessarabicum; and St was contributed from the genus Pseudoroegneria by hybridization with Th. junceiforme or Th. sartorii.

Loss of anthocyanidin synthase gene is associated with white flowers of Salvia miltiorrhiza Bge. f. alba, a natural variant of S. miltiorrhiza.

MAIN CONCLUSION: SmANS deletion leads to white flower mutation in Salvia miltiorrhiza. SmANS deletion leads to white flower mutation in Salvia miltiorrhiza. Abstract Salvia miltiorrhiza is an essential traditional Chinese medicine (TCM) with purple flowers, and S. miltiorrhiza Bge. f. alba is a unique intraspecific variation with white flowers. The molecular mechanism of flower color formation in S. miltiorrhiza will provide vital information for the variation and evolution. Here, we performed HPLC, transcriptomic, and re-sequencing analyses of purple-flowered S. miltiorrhiza line 'Zihua105' (ZH105) and white-flowered S. miltiorrhiza Bge. f. alba line 'Baihua18' (BH18). Delphinidin was the most anthocyanidin in ZH105, which become the main different between ZH105 vs. BH18 flowers. Transcriptome analysis revealed 299 differentially expressed genes (DEGs). SmANS, the anthocyanidin synthase gene in the down-stream anthocyanin biosynthesis pathway, was significantly expressed in ZH105 corollas, suggesting it might play a key role in white petal formation. Whole-genome re-sequencing revealed that a 6.75 kb segment located on chromosome 5, which contains the complete sequence of the SmANS genes, was lost in BH18 and another S. miltiorrhiza Bge. f. alba line. In contrast, the other five purple-flowered S. miltiorrhiza lines both possessed this segment. Further molecular marker identification also confirmed that wild S. miltiorrhiza Bge. f. alba lines lost regions that contained a complete or important part of SmANS sequences. Subsequently, the research showed that the deletion mutant of SmANS genes resulted in the natural white flower color variant of S. miltiorrhiza.

SmGDB: genome database of Salvia miltiorrhiza, an important TCM Plant.

BACKGROUND: Salvia miltiorrhiza is an important traditional Chinese medicinal (TCM) plant and a model plant in the genetic study of TCM. A series of omics related to Danshen have been published. Integrating, managing, storing, and sharing data has become an urgent problem to be solved in S. miltiorrhiza genetic studies. OBJECTIVES: The genome database is the link for the exchange, acquisition, and use of different omics data between data producers and users, maximizing value and utilization of data. METHODS: The genome database included DSS3 genome and five RNA-Seq data. The back-end performs data search and retrieval through the LAMP (Linux, Apache, MySQL, PHP) framework. RESULTS: Here, we present SmGDB (S. miltiorrhiza genome database; http://8.140.162.85/ ), which houses the latest version of genome sequence and annotation data for S. miltiorrhiza, combining three unpublished RNA-Seq data from our group and two released RNA-Seq data. We also identified a novel gene cluster including seven CYP71D genes involved in the tanshinone synthesis pathway based on genome sequences and expression data. Besides, SmGDB provides user-friendly web interfaces for querying and browsing gene annotation, structure, location, and expression profiles for concerned genes. Popular bioinformatics tools such as 'BLAST', 'Search', 'Heatmap', 'JBrowse', etc., were also provided in SmGDB. CONCLUSIONS: SmGDB will provide utility for characterizing the structure of the S. miltiorrhiza genome and better understanding gene functions and biological processes underlying complex secondary metabolism in Danshen.

Characterization of chromosome constitution in three wheat - Thinopyrum intermedium amphiploids revealed frequent rearrangement of alien and wheat chromosomes.

BACKGROUND: Thinopyrum intermedium (2n = 6x = 42) is an important wild perennial Triticeae species exhibiting many potentially favorable traits for wheat improvement. Wheat-Th. intermedium partial amphiploids serve as a bridge to transfer desirable genes from Th. intermedium into common wheat. RESULTS: Three octoploid Trititrigia accessions (TE261-1, TE266-1, and TE346-1) with good resistances to stripe rust, powdery mildew and aphids were selected from hybrid progenies between Th. intermedium and the common wheat variety 'Yannong 15' (YN15). Genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH) and multicolor GISH (McGISH) analyses demonstrated that the three octoploid Trititrigia possess 42 wheat chromosomes and 14 Th. intermedium chromosomes. The 14 alien (Th. intermedium) chromosomes belong to a mixed genome consisting of J-, JS- and St-genome chromosomes rather than a single J, JS or St genome. Different types of chromosomal structural variation were also detected in the 1A, 6A, 6B, 2D and 7D chromosomes via FISH, McGISH and molecular marker analysis. The identity of the alien chromosomes and the variationes in the wheat chromosomes in the three Trititrigia octoploids were also different. CONCLUSIONS: The wheat-Th. intermedium partial amphiploids possess 14 alien chromosomes which belong to a mixed genome consisting of J-, JS- and St- chromosomes, and 42 wheat chromosomes with different structural variations. These accessions could be used as genetic resources in wheat breeding for the transfer of disease and pest resistance genes from Th. intermedium to common wheat.

A high-quality reference genome sequence of Salvia miltiorrhiza provides insights into tanshinone synthesis in its red rhizomes.

Salvia miltiorrhiza Bunge, also known as red sage or Danshen, is an important traditional Chinese medicine (TCM) that has been used for thousands of years to treat cardiovascular and other diseases. It is also considered an important model TCM plant. Here, a high-quality reference genome of S. miltiorrhiza was generated by combining PacBio long-read sequencing and chromatin interaction mapping (Hi-C) technologies, resulting in the chromosome-scale assembly of a 594.75-Mb genome sequence with a contig N50 of 2.70 Mb. This assembly shows the highest level of continuity for a Danshen genome generated thus far. The S. miltiorrhiza genome contained 32,483 protein-coding genes, with a repetitive DNA content of approximately 64.84%. The high percentage of young LTRs suggests that multiple TE transposition bursts occurred recently in S. miltiorrhiza. Genes unique to secondary metabolism pathways were expanded in the S. miltiorrhiza genome. A new CYP450 gene cluster was identified in the phloem of red roots where active components were synthesized. This reference genome sequence will facilitate future studies aimed at the elucidation of the secondary metabolism synthesis pathway and the genetic improvement of S. miltiorrhiza.

Comparative Transcriptome Analyses of Resistant and Susceptible Near-Isogenic Wheat Lines following Inoculation with Blumeria graminis f. sp. tritici.

Powdery mildew is one of the most important diseases of wheat. In this study, the leaf RNA samples of wheat NILs carrying powdery mildew resistant and susceptible Pm2 alleles (L031 and Chancellor) and its F1 hybrid at two time points (16 h and 96 h postinoculation) were used for RNA-seq analysis. We carry comparison between similar materials at different times and between different materials at same times. The overlapping DEGs between the dominant phenotypes (L031 and F1 hybrid) and the recessive phenotype (Chancellor) were 1028 and 2214 DEGs, which were clearly lower than those between the dominant and recessive parents and thus could provide relatively accurate and valuable information. GO and KEGG enrichment analysis of DEGs revealed that other than the expected defense-related genes, differential up- and downregulation of genes from many other signaling networks were also involved. Comparative transcriptome analysis also revealed that early-stage postinoculation is important and suitable time points to study expression profiles and signaling pathways of resistance-related genes following fungal inoculation. qRT-PCR analyses showed highly consistent expression patterns of genes with RNA-seq data. The results will aid in the identification of genes and signaling pathways involved in powdery mildew response in wheat.

Chromosome Pairing in Hybrid Progeny between Triticum aestivum and Elytrigia elongata.

In this study, the intergeneric hybrids F1, F2, BC1F1, BC1F2, and BC2F1 from Elytrigia elongata and Triticum aestivum crosses were produced to study their chromosome pairing behavior. The average E. elongata chromosome configuration of the two F1 hybrids agreed with the theoretical chromosome configuration of 21I+7II, indicating that the genomic constitution of this F1 hybrid was ABDStStEeEbEx. Compared with the BC1F1 generation, the BC2F1 generation showed a rapid decrease in the number of E. elongata chromosomes and the BC1F2 generation showed a more extensive distribution of E. elongata chromosomes. In addition, pairing between wheat and E. elongata chromosomes was detected in each of the wheat-E. elongata hybrid progenies, albeit rarely. Our results demonstrated that genomic in situ hybridization (GISH) using an E. elongata genomic DNA probe offers a reliable approach for characterizing chromosome pairing in wheat and E. elongata hybrid progenies.