Floral Transcriptome Sequencing for SSR Marker Development and Linkage Map Construction in the Tea Plant (<i>Camellia sinensis</i>)

<div><p>Despite the worldwide consumption and high economic importance of tea, the plant (<i>Camellia sinensis</i>) is not well studied in molecular biology. Under the few circumstances in which the plant is studied, <i>C. sinensis</i> 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 <i>C. sinensis</i> 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 <i>C. sinensis</i>. 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 <i>C. sinensis</i> 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.</p>