Cell‐type‐ and tissue‐specific transcriptomes of the white spruce (Picea glauca) bark unmask fine‐scale spatial patterns of constitutive and induced conifer defense. (28th September 2017)

• Record Type: Journal Article
• Authors: Celedon, Jose M.; Yuen, Macaire M.S.; Chiang, Angela; Henderson, Hannah; Reid, Karen E.; Bohlmann, Jörg
• Is Part Of: Plant journal. Volume 92:Number 4(2017)
• Page Start: 710
• Page End: 726
• Publication Date: 2017-09-28
• Subjects: laser microdissection -- RNA‐Seq -- methyl jasmonate -- cortical resin duct -- phenolic cells -- terpenes -- phenylpropanoid; Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.13673
• Languages: English
• ISSNs: 0960-7412

Abstract

Summary: Plant defenses often involve specialized cells and tissues. In conifers, specialized cells of the bark are important for defense against insects and pathogens. Using laser microdissection, we characterized the transcriptomes of cortical resin duct cells, phenolic cells and phloem of white spruce ( Picea glauca ) bark under constitutive and methyl jasmonate (MeJa)‐induced conditions, and we compared these transcriptomes with the transcriptome of the bark tissue complex. Overall, ~3700 bark transcripts were differentially expressed in response to MeJa. Approximately 25% of transcripts were expressed in only one cell type, revealing cell specialization at the transcriptome level. MeJa caused cell‐type‐specific transcriptome responses and changed the overall patterns of cell‐type‐specific transcript accumulation. Comparison of transcriptomes of the conifer bark tissue complex and specialized cells resolved a masking effect inherent to transcriptome analysis of complex tissues, and showed the actual cell‐type‐specific transcriptome signatures. Characterization of cell‐type‐specific transcriptomes is critical to reveal the dynamic patterns of spatial and temporal display of constitutive and induced defense systems in a complex plant tissue or organ. This was demonstrated with the improved resolution of spatially restricted expression of sets of genes of secondary metabolism in the specialized cell types. Significance Statement: Long‐lived conifers, which dominate many of the world's forest ecosystems, are typically well defended against herbivores and pathogens through chemical defenses localized in the outer stem tissues. Using laser microdissection and RNA‐Seq against the background of a sequenced genome, this study provides a comprehensive transcriptome resource of specialized cell‐types of the constitutive and induced conifer defense system and its spatially refined analysis.