Genome-wide transcriptome profiling provides new insights into bud dormancy in pear

Abstract

Dormancy is important for the pear (Pyrus pyrifolia) to survive a harsh environment. The molecular base of dormancy in pear, especially in some local cultivars, is still unclear. Genome-wide transcriptome analysis in flower buds of cv. Huangli (an excellent local cultivar native to Guizhou mountain area in China) was conducted to explore the mechanism regulating bud dormancy in pear. For the release of endo-dormancy 223 chilling hours (CHs) was needed in Huangli flower buds, which was less than in commercial cultivars. Comparisons of transcript amounts among seven dates during dormancy (30 Oct. vs. 15 Nov., 15 Nov. vs. 30 Nov., 30 Nov. vs. 15 Dec., 15 Dec. vs. 30 Dec., 30 Dec. vs. 15 Jan., and 15 Jan vs. 15 Feb.), resulted in the detection of 1 064, 1 057, 541, 412, 577, and 3 814 differentially expressed transcripts, respectively. The reference genome of pear was used to align the RNA-Seq reads and to measure the transcript expression. Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) were then used to annotate the transcript descriptions and to assign a pathway to each transcript. The results revealed, that secondary metabolite biosynthesis, especially phenylpropanoid biosynthesis pathway, was the most enriched pathway out of 132 pathways. These interesting results indicated that dormancy in Huangli might be regulated mainly by secondary metabolite biosynthesis pathway, and the two continuous dormant stages (endo-dormancy and eco-dormancy) might be regulated specifically by phenylpropanoid biosynthesis and plant hormone signal transduction, respectively.

Keywords

• chilling hours
• phenylpropanoid biosynthesis pathway
• pyrus pyrifolia
• rna-seq