Despite the worldwide consumption and high economic importance of tea, the plant (Camellia sinensis) is not well studied in molecular biology. Under the few circumstances in which the plant is studied, C. sinensis flowers, which are important for reproduction and cross-breeding, receive less emphasis than investigation of its leaves or roots. Using high-throughput Illumina RNA sequencing, we analyzed a C. sinensis floral transcriptome, and 26.9 million clean reads were assembled into 75,531 unigenes averaging 402 bp. Among them, 50,792 (67.2%) unigenes were annotated with a BLAST search against the NCBI Non-Redundant (NR) database and 10,290 (16.67%) were detected that contained one or more simple sequence repeats (SSRs). From these SSR-containing sequences, 2,439 candidate SSR markers were developed and 720 were experimentally tested, validating 431 (59.9%) novel polymorphic SSR markers for C. sinensis. Then, a consensus SSR-based linkage map was constructed that covered 1,156.9 cM with 237 SSR markers distributed in 15 linkage groups. Both transcriptome information and the genetic map of C. sinensis presented here offer a valuable foundation for molecular biology investigations such as functional gene isolation, quantitative trait loci mapping, and marker-assisted selection breeding in this important species.
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"As a result, a total of 40,823 EST-SSRs were detected in 25,188 unigenes (44.1% of the total searched unigenes;Table S8), equivalent to an average frequency of one SSR per 1.74 kilo-nucleotides (Knt) of the transcriptome sequences. This result was slightly more frequent than those reported in a corresponding study on tea (2.41 Knt) that used different parameters (Tan et al., 2013). The most abundant repeat type was trinucleotide (14,688, 36.0%), "
[Show abstract][Hide abstract]ABSTRACT: Camellia reticulata, which is native to Southwest China, is famous for its ornamental flowers and high-quality seed oil. However, the lack of genomic information for this species has largely hampered our understanding of its key pathways related to oil production, photoperiodic flowering process and pigment biosynthesis. Here, we first sequenced and characterized the transcriptome of a diploid C. reticulata in an attempt to identify genes potentially involved in triacylglycerol biosynthesis (TAGBS), photoperiodic flowering, flavonoid biosynthesis (FlaBS), carotenoid biosynthesis (CrtBS) pathways. De novo assembly of the transcriptome provided a catalog of 141,460 unigenes with a total length of ~96.1 million nucleotides (Mnt) and an N50 of 1080 nt. Of them, 22,229 unigenes were defined as differentially expressed genes (DEGs) across five sequenced tissues. A large number of annotated genes in C. reticulata were found to have been duplicated, and differential expression patterns of these duplicated genes were commonly observed across tissues, such as the differential expression of SOC1_a, SOC1_b, and SOC1_c in the photoperiodic flowering pathway. Up-regulation of SAD_a and FATA genes and down-regulation of FAD2_a gene in the TAGBS pathway in seeds may be relevant to the ratio of monounsaturated fatty acid (MUFAs) to polyunsaturated fatty acid (PUFAs) in seed oil. MYBF1, a transcription regulator gene of the FlaBS pathway, was found with great sequence variation and alteration of expression patterns, probably resulting in functionally evolutionary differentiation in C. reticulata. MYBA1_a and some anthocyanin-specific biosynthetic genes in the FlaBS pathway were highly expressed in both flower buds and flowers, suggesting important roles of anthocyanin biosynthesis in flower development. Besides, a total of 40,823 expressed sequence tag simple sequence repeats (EST-SSRs) were identified in the C. reticulata transcriptome, providing valuable marker resources for further basic and applied researches on this economically important Camellia plant.
Full-text · Article · Feb 2016 · Frontiers in Plant Science
[Show abstract][Hide abstract]ABSTRACT: Tea is an important health drink which contributes significantly to the economy of Asian and African countries. India contributes about 29 % of the world’s total tea production where majority of the tea cultivated is Assam type (native to Assam, India). Apart from India, Assam type contributes to the majority of tea grown in tropical regions of Sri Lanka and Kenya as well. We have developed the first genetic linkage map in Indian beveragial tea using 234 DNA markers (AFLP and RAPD). The plausibility of the linkage group formation was compared using two-way pseudo-testcross approach (using maximum likelihood algorithm) and integrated approaches (using regression algorithm). Both the approaches generated linkage maps containing 18 linkage groups. The composition and order of markers in the corresponding linkage groups in both the maps showed significant congruence. Maximum likelihood algorithm could map 78.6 % of the markers with total map length of 8527.5 and 45.3 cM average distance between each marker. Regression algorithm could map 73.5 % of the total markers with total map length of 2051.7 and 14.96 cM average distance between each marker. Drought is the major abiotic stress responsible for heavy yield losses in cultivated tea all over the world. The present map was used to map the locus, AFLP_CS_87 that segregates with drought tolerance phenotype in both the maps.
Full-text · Article · May 2015 · Molecular Breeding
[Show abstract][Hide abstract]ABSTRACT: Medicinal plants have been of great importance to human health care since the advent of medicine. A huge array of molecules has been obtained from these phytopharmaceutical-yielding species that have influenced human lives since the beginning of plant-based life-saving medicines. Some of these molecules have taken the form of taxol, aspirin, and artemisinin. With the flourishing era of high throughput next generation sequencing technologies, a hot pursuit for sequencing the genomes and transcriptomes of these life-saving plants is underway. Although few genomes have been sequenced or are currently being addressed, the number of transcriptomes sequenced has sky-rocketed in the last couple of years and continues to surge forward with immense pace, covering all important genera of medicinal plants. I have attempted to provide the current status, progress, opportunities, and challenges of these sequencing endeavors in this comprehensive and updated review. It is my hope that this information will provide both specialists and non-specialists with the current trends and future directions of this interesting category of plants.