SSR individual identification system construction and population genetics analysis for Chamaecyparis formosensis

Simultaneous determination of subspecies and geographic origins of 110 rice cultivars by microsatellite markers

Rice varieties of different subspecies types (indica rice and japonica rice) across various geographical origins (Hunan, Jiangsu, and Northeast China) were monitored using microsatellite markers (simple sequence repeats, SSR). 110 representative rice cultivars were collected from the main crop areas. Multiple methods including clustering analysis (neighbor-joining (NJ) method, unweighted pair-group method with arithmetic mean (UPGMA) method), principal component analysis (PCA) and model-based grouping were applied. The study revealed that 25 pairs of SSR markers exhibited a broad range of polymorphism information content (PIC) values, ranging from 0.240 to 0.830. Furthermore, our study successfully achieved a higher overall mean correct rate of 99.09% in determining the geographical origin of rice. Simultaneously, it accurately classified indica rice and japonica rice. These findings are significant as they provide an SSR fingerprint of 110 high-quality rice cultivars, serving as a valuable scientific resource for the detection of rice adulteration and traceability of its origin.

Transcriptome sequencing of medical herb Salvia Rosmarinus (Rosemary) revealed the phenylpropanoid biosynthesis pathway genes and their phylogenetic relationships

BACKGROUND

The Salvia rosmarinus spenn. (rosemary) is considered an economically important ornamental and medicinal plant and is widely utilized in culinary and for treating several diseases. However, the procedure behind synthesizing secondary metabolites-based bioactive compounds at the molecular level in S. rosmarinus is not explored completely.

METHODS AND RESULTS

We performed transcriptomic sequencing of the pooled sample from leaf and stem tissues on the Illumina HiSeqTM X10 platform. The transcriptomics analysis led to the generation of 29,523,608 raw reads, followed by data pre-processing which generated 23,208,592 clean reads, and de novo assembly of S. rosmarinus obtained 166,849 unigenes. Among them, nearly 75.1% of unigenes i.e., 28,757 were interpreted against a non-redundant protein database. The gene ontology-based annotation classified them into 3 main categories and 55 sub-categories, and clusters of orthologous genes annotation categorized them into 23 functional categories. The Kyoto Encyclopedia of Genes and Genomes database-based pathway analysis confirmed the involvement of 13,402 unigenes in 183 biochemical pathways, among these unigenes, 1,186 are involved in the 17 secondary metabolite production pathways. Several key enzymes involved in producing aromatic amino acids and phenylpropanoids were identified from the transcriptome database. Among the identified 48 families of transcription factors from coding unigenes, bHLH, MYB, WRKYs, NAC, C2H2, C3H, and ERF are involved in flavonoids and other secondary metabolites biosynthesis.

CONCLUSION

The phylogenetic analysis revealed the evolutionary relationship between the phenylpropanoid pathway genes of rosemary with other members of Lamiaceae. Our work reveals a new molecular mechanism behind the biosynthesis of phenylpropanoids and their regulation in rosemary plants.

A taxonomic revision of the genus Angelica (Apiaceae) in Taiwan with a new species A. aliensis

BACKGROUND

Angelica L. sensu lato is a taxonomically complex genus, and many studies have utilized morphological and molecular features to resolve its classification issues. In Taiwan, there are six taxa within Angelica, and their taxonomic treatments have been a subject of controversy. In this study, we conducted a comprehensive analysis incorporating morphological and molecular (cpDNA and nrDNA) characteristics to revise the taxonomic treatments of Angelica in Taiwan.

RESULTS

As a result of our research, we have revised the classification between A. dahurica var. formosana and A. pubescens and merged two varieties of A. morrisonicola into a single taxon. A new taxon, A. aliensis, has been identified and found to share a close relationship with A. tarokoensis. Based on the morphological and molecular characteristics data, it has been determined that the former three taxa should be grouped into the Eurasian Angelica clade, while the remaining four taxa should belong to the littoral Angelica clade. Furthermore, Angelica species in Taiwan distributed at higher altitudes displayed higher genetic diversity, implying that the central mountain range of Taiwan serves as a significant reservoir of plant biodiversity. Genetic drift, such as bottlenecks, has been identified as a potential factor leading to the fixation or reduction of genetic diversity of populations in most Angelica species. We provide key to taxa, synopsis, phenology, and distribution for each taxon of Taiwan.

CONCLUSIONS

Our comprehensive analysis of morphological and molecular features has shed light on the taxonomic complexities within Angelica in Taiwan, resolving taxonomic issues and providing valuable insights into the phylogenetic relationships of Angelica in Taiwan.

S. A, H. B. M, Singh P, M. R. B, P S, Burji SM, T. M, V. S. Genome size, genetic diversity, and phenotypic variability imply the effect of genetic variation instead of ploidy on trait plasticity in the cross-pollinated tree species of mulberry

Elucidation of genome size (GS), genetic and phenotypic variation is the fundamental aspect of crop improvement programs. Mulberry is a cross-pollinated, highly heterozygous tree eudicot, and comprised of huge ploidy variation with great adaptability across the world. However, because of inadequate information on GS, ploidy-associated traits, as well as the correlation between genetic and phenotypic variation hinder the further improvement of mulberry. In this present research, a core set of 157 germplasm accessions belonging to eight accepted species of Morus including promising functional varieties were chosen to represent the genetic spectrum from the whole germplasm collection. To estimate the GS, accessions were subjected to flow cytometry (FCM) analysis and the result suggested that four different ploidies (2n = 2x, 3x, 4x, and 6x) with GS ranging from 0.72±0.005pg (S-30) to 2.89±0.015pg (M. serrata), accounting~4.01 fold difference. The predicted polyploidy was further confirmed with metaphase chromosome count. In addition, the genetic variation was estimated by selecting a representative morphologically, diverse population of 82 accessions comprised of all ploidy variations using simple sequence repeats (SSR). The estimated average Polymorphism Information Content (PIC) and expected heterozygosity showed high levels of genetic diversity. Additionally, three populations were identified by the model-based population structure (k = 3) with a moderate level of correlation between the populations and different species of mulberry, which imply the effect of genetic variation instead of ploidy on trait plasticity that could be a consequence of the high level of heterozygosity imposed by natural cross-pollination. Further, the correlation between ploidies, especially diploid and triploid with selected phenotypic traits was identified, however, consistency could not be defined with higher ploidy levels (>3x). Moreover, incite gained here can serve as a platform for future omics approaches to the improvement of mulberry traits.

Transcriptome Analysis Reveals Genes Associated with Flooding Tolerance in Mulberry Plants

Mulberry (Morus alba), a widely distributed economic plant, can withstand long-term flooding stress. However, the regulatory gene network underlying this tolerance is unknown. In the present study, mulberry plants were subjected to submergence stress. Subsequently, mulberry leaves were collected to perform quantitative reverse-transcription PCR (qRT-PCR) and transcriptome analysis. Genes encoding ascorbate peroxidase and glutathione S-transferase were significantly upregulated after submergence stress, indicating that they could protect the mulberry plant from flood damage by mediating ROS homeostasis. Genes that regulate starch and sucrose metabolism; genes encoding pyruvate kinase, alcohol dehydrogenase, and pyruvate decarboxylase (enzymes involved in glycolysis and ethanol fermentation); and genes encoding malate dehydrogenase and ATPase (enzymes involved in the TCA cycle) were also obviously upregulated. Hence, these genes likely played a key role in mitigating energy shortage during flooding stress. In addition, genes associated with ethylene, cytokinin, abscisic acid, and MAPK signaling; genes involved in phenylpropanoid biosynthesis; and transcription factor genes also showed upregulation under flooding stress in mulberry plants. These results provide further insights into the adaptation mechanisms and genetics of submergence tolerance in mulberry plants and could aid in the molecular breeding of these plants.

Effect of geographic isolation on genetic variation and population structure of Euphrasia nankotaizanensis, a threatened endemic alpine herb in Taiwan

Euphrasia nankotaizanensis (Orobanchaceae) is a rare alpine herb that is endemic to Taiwan. Only four small populations remain in Xue, Nanhu, and Cilai Mountains of Taiwan. The distribution of alpine herbs is severely threatened by climate change, which influences genetic variation and population structure. In this study, we investigated the effects of the natural isolation of alpine habitats on the genetic diversity and geographic structure of populations of E. nankotaizanensis using chloroplast (cp) and nuclear DNA (nrDNA) markers. We found lower levels of genetic diversity in E. nankotaizanensis than in other alpine plants and little to no genetic variation within populations, which could be mainly attributed to the small population size and genetic drift. Only one nrDNA haplotype was present in each population. The lack of monophyly of the four populations in cpDNA probably resulted from lineage sorting or occasional long-distance seed dispersal. Phylogeographic analysis suggested that Nanhu Mountain was probably a refugium over the glacial maxima, agreeing with the potential refugia in central Taiwan. The STRUCTURE and AMOVA analyses revealed significant genetic differentiation in nrDNA among the mountains, which resulted from geographical isolation among these mountains. Estimates of the effective population size (Ne) and demography reflected lower Ne values and a recent population decline, probably implying a greater extinction risk for E. nankotaizanensis. We observed genetic depletion and considerable genetic differentiation among mountain populations, which should be considered in future conservation efforts for this species. In addition, this study provides important insights into the long-term potential of alpine herbs in Taiwan, which are useful for a better prediction of their responses to future climate change.

Identification of novel SSR markers for predicting the geographic origin of fungus Schizophyllum commune Fr

The fungus Schizophyllum commune is a cosmopolitan basidiomycete, which is popular as an edible, medical mushroom. It causes wood rot and often used as a model object in research. In this study, we analyzed thirty-two genomes of S. commune strains from the NCBI database and designed forty-seven unique SSR DNA markers. The detailed analysis revealed the enrichment of the S. commune genome for CG, GC, CTC, GAG, and TCG motifs. Principal components analysis confirmed the effectiveness of novel SSR DNA markers that preserve the initial heterogeneity of populations. The construction of a network between strains showed single one at a maximum similarity of 38%, and increasing the similarity to 55% breaks the linkage between large groups while separating two new groups containing strains of the population Ru and test cultures S. commune. The amplicons' presence was identified as a sufficient sign of relation of the culture to a specific population. Testing the novel SSR markers allowed to establish a clear delimitation of all groups by geographic location and to differentiate the H4-8 (GCA_000143185.1) strain from the USA population. This research is the basis for the further analysis of S. commune populations and improvement of approaches to determine its genetic diversity.

Comprehensive Analyses of Simple Sequence Repeat (SSR) in Bamboo Genomes and Development of SSR Markers with Peroxidase Genes

Simple sequence repeats (SSRs) are one of the most important molecular markers, which are widespread in plants. Bamboos are important forest resources worldwide. Here, the comprehensive identification and comparative analysis of SSRs were performed in three woody and two herbaceous bamboo species. Altogether 567,175 perfect SSRs and 71,141 compound SSRs were identified from 5737.8 Mb genome sequences of five bamboo species. Di-nucleotide SSRs were the most predominant type, with an average of ~50,152.2 per species. Most SSRs were located in intergenic regions, while those located in genic regions were relatively less. Moreover, the results of annotation distribution indicated that terms with P450, peroxidase and ATP-binding cassette transporter related to lignin biosynthesis might play important roles in woody and herbaceous bamboos under the mediation of SSRs. Furthermore, the peroxidase gene family consisted of a large number of genes containing SSRs was selected for the evolutionary relationship analysis and SSR markers development. Fifteen SSR markers derived from peroxidase family genes of Phyllostachys edulis were identified as polymorphic in 34 accessions belonging to seven genera in Bambusoideae. These results provided a comprehensive insight of SSR markers into bamboo genomes, which would facilitate bamboo research related to comparative genomics, evolution and marker-assisted selection.