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Sclerotinia stem rot (SSR) caused by Sclerotinia sclerotiorum (S. sclerotiorum) is the main disease threat of oilseed rape (Brassica napus), resulting in huge economic losses every year. SSR resistance manifests as quantitative disease resistance (QDR), and no gene with complete SSR resistance has been cloned or reported so far. Transcriptome analysis has revealed a large number of defense-related genes and response processes. However, the similarities and differences in the defense responses of different tissues are rarely reported. In this study, we analyzed the similarities and differences of different tissues in response to S. sclerotiorum at 24 h post inoculation (hpi) by using the published transcriptome data for respective leaf and stem inoculation. At 24 hpi, large differences in gene expression exist in leaf and stem, and there are more differentially expressed genes and larger expression differences in leaf. The leaf is more sensitive to S. sclerotiorum and shows a stronger response than stem. Different defense responses appear in the leaf and stem, and the biosynthesis of lignin, callose, lectin, chitinase, PGIP, and PR protein is activated in leaf. In the stem, lipid metabolism-mediated defense responses are obviously enhanced. For the common defense responses in both leaf and stem, the chain reactions resulting from signal transduction and biological process take the primary responsibility. This research will be beneficial to exploit the potential of different tissues in plant defense and find higher resistance levels of genotypic variability in different environments. Our results are significant in the identification of resistance genes and analysis of defense mechanisms. [ABSTRACT FROM AUTHOR]

Brassica napus (oilseed rape) is an economically important oil crop worldwide. Sclerotinia stem rot (SSR) caused by Sclerotinia sclerotiorum is a threat to oilseed rape production. Because the flower petals play pivotal roles in the SSR disease cycle, it is useful to express the resistance-related genes specifically in flowers to hinder further infection with S. sclerotiorum. To screen flower-specific promoters, we first analyzed the transcriptome data from 12 different tissues of the B. napus line ZS11. In total, 249 flower-specific candidate genes with high expression in petals were identified, and the expression patterns of 30 candidate genes were verified by quantitative real-time transcription-PCR (qRT-PCR) analysis. Furthermore, two novel flower-specific promoters (FSP046 and FSP061 promoter) were identified, and the tissue specificity and continuous expression in petals were determined in transgenic Arabidopsis thaliana with fusing the promoters to β-glucuronidase (GUS)-reporter gene. GUS staining, transcript expression pattern, and GUS activity analysis indicated that FSP046 and FSP061 promoter were strictly flower-specific promoters, and FSP046 promoter had a stronger activity. The two promoters were further confirmed to be able to direct GUS expression in B. napus flowers using transient expression system. The transcriptome data and the flower-specific promoters screened in the present study will benefit fundamental research for improving the agronomic traits as well as disease and pest control in a tissue-specific manner. [ABSTRACT FROM AUTHOR]