BackgroundThe use of cytoplasmic male sterility (CMS) in F1 hybrid seed production of chili pepper is increasingly popular. However, the molecular mechanisms of cytoplasmic male sterility and fertility restoration remain poorly understood due to limited transcriptomic and genomic data. Therefore, we analyzed the difference between a CMS line 121A and its near-isogenic restorer line 121C in transcriptome level using next generation sequencing technology (NGS), aiming to find out critical genes and pathways associated with the male sterility.ResultsWe generated approximately 53 million sequencing reads and assembled de novo, yielding 85,144 high quality unigenes with an average length of 643 bp. Among these unigenes, 27,191 were identified as putative homologs of annotated sequences in the public protein databases, 4,326 and 7,061 unigenes were found to be highly abundant in lines 121A and 121C, respectively. Many of the differentially expressed unigenes represent a set of potential candidate genes associated with the formation or abortion of pollen.ConclusionsOur study profiled anther transcriptomes of a chili pepper CMS line and its restorer line. The results shed the lights on the occurrence and recovery of the disturbances in nuclear-mitochondrial interaction and provide clues for further investigations.

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Phytophthora capsici (Leonian), classified as an oomycete, seriously threatens the production of pepper (Capsicum annuum). Current understanding of the defense responses in pepper to P. capsici is limited. In this study, RNA-sequencing analysis was utilized to identify differentially expressed genes in the resistant line “PI 201234”, with 1220 differentially expressed genes detected. Of those genes, 480 were up-regulated and 740 were down-regulated, with 211 candidate genes found to be involved in defense responses based on the gene annotations. Furthermore, the expression patterns of 12 candidate genes were further validated via quantitative real-time PCR (qPCR). These genes were found to be significantly up-regulated at different time points post-inoculation (6 hpi, 24 hpi, and 5 dpi) in the resistant line “PI 201234” and susceptible line “Qiemen”. Seven genes were found to be involved in cell wall modification, phytoalexin biosynthesis, symptom development, and phytohormone signaling pathways, thus possibly playing important roles in combating exogenous pathogens. The genes identified herein will provide a basis for further gene cloning and functional verification studies and will aid in an understanding of the regulatory mechanism of pepper resistance to P. capsici.

Celery (Apium graveolens L.) is one of the most economically important vegetables worldwide, but genetic and genomic resources supporting celery molecular breeding are quite limited, thus few studies on celery have been conducted so far. In this study we made use of simple sequence repeat (SSR) markers generated from previous celery transcriptome sequencing and attempted to detect the genetic diversity and relationships of commonly used celery accessions and explore the efficiency of the primers used for cultivars identification. Analysis of molecular variance (AMOVA) of Apium graveolens L. var. dulce showed that approximately 43% of genetic diversity was within accessions, 45% among accessions, and 22% among horticultural types. The neighbor-joining tree generated by unweighted pair group method with arithmetic mean (UPGMA), and population structure analysis, as well as principal components analysis (PCA), separated the cultivars into clusters corresponding to the geographical areas where they originated. Genetic distance analysis suggested that genetic variation within Apium graveolens was quite limited. Genotypic diversity showed any combinations of 55 genic SSRs were able to distinguish the genotypes of all 30 accessions.