title: Digital Gene Expression Analysis of Populus simonii × P. nigra Pollen Germination and Tube Growth.
abstract: Pollen tubes are an ideal model for the study of cell growth and morphogenesis because of their extreme elongation without cell division; however, the genetic basis of pollen germination and tube growth remains largely unknown. Using the Illumina/Solexa digital gene expression system, we identified 13,017 genes (representing 28.3% of the unigenes on the reference genes) at three stages, including mature pollen, hydrated pollen, and pollen tubes of Populus simonii × P. nigra. Comprehensive analysis of P. simonii × P. nigra pollen revealed dynamic changes in the transcriptome during pollen germination and pollen tube growth (PTG). Gene ontology analysis of differentially expressed genes showed that genes involved in functional categories such as catalytic activity, binding, transporter activity, and enzyme regulator activity were overrepresented during pollen germination and PTG. Some highly dynamic genes involved in pollen germination and PTG were detected by clustering analysis. Genes related to some key pathways such as the mitogen-activated protein kinase signaling pathway, regulation of the actin cytoskeleton, calcium signaling, and ubiquitin-mediated proteolysis were significantly changed during pollen germination and PTG. These data provide comprehensive molecular information toward further understanding molecular mechanisms underlying pollen germination and PTG.
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Northeast Forestry UniversityHarbin, China; Department of Crop Molecular Breeding, Crop Breeding Institute, Heilongjiang Academy of Agricultural SciencesHarbin, China.
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Zhao
authors.affiliation: Medical Plant Research Center, Economic Crop Institute, Heilongjiang Academy of Agricultural Sciences Harbin, China.
authors.forename: Hong-Mei
authors.initials: HM
authors.lastname: Yuan
authors.affiliation: Biotechnology Research Center, Institute of Natural Resources and Ecology, Heilongjiang Academy of Sciences Harbin, China.
authors.forename: Wen-Dong
authors.initials: WD
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Northeast Forestry University Harbin, China.
authors.forename: Chuan-Ping
authors.initials: CP
authors.lastname: Yang
keywords: DGE; Populus simonii × P. nigra pollen; differentially expressed genes; pollen germination; pollen tube growth; transcription