Transcript Profile of Flowering Regulatory Genes in VcFT-Overexpressing Blueberry Plants.
In order to identify genetic components in flowering pathways of highbush blueberry (Vaccinium corymbosum L.), a transcriptome reference composed of 254,396 transcripts and 179,853 gene contigs was developed by assembly of 72.7 million reads using Trinity. Using this transcriptome reference and a query of flowering pathway genes of herbaceous plants, we identified potential flowering pathway genes/transcripts of blueberry. Transcriptome analysis of flowering pathway genes was then conducted on leaf tissue samples of transgenic blueberry cv. Aurora ('VcFT-Aurora'), which overexpresses a blueberry FLOWERING LOCUS T-like gene (VcFT). Sixty-one blueberry transcripts of 40 genes showed high similarities to 33 known flowering-related genes of herbaceous plants, of which 17 down-regulated and 16 up-regulated genes were identified in 'VcFT-Aurora'. All down-regulated genes encoded transcription factors/enzymes upstream in the signaling pathway containing VcFT. A blueberry CONSTANS-LIKE 5-like (VcCOL5) gene was down-regulated and associated with five other differentially expressed (DE) genes in the photoperiod-mediated flowering pathway. Three down-regulated genes, i.e., a MADS-AFFECTING FLOWERING 2-like gene (VcMAF2), a MADS-AFFECTING FLOWERING 5-like gene (VcMAF5), and a VERNALIZATION1-like gene (VcVRN1), may function as integrators in place of FLOWERING LOCUS C (FLC) in the vernalization pathway. Because no CONSTAN1-like or FLOWERING LOCUS C-like genes were found in blueberry, VcCOL5 and VcMAF2/VcMAF5 or VRN1 might be the major integrator(s) in the photoperiod- and vernalization-mediated flowering pathway, respectively. The major down-stream genes of VcFT, i.e., SUPPRESSOR of Overexpression of Constans 1-like (VcSOC1), LEAFY-like (VcLFY), APETALA1-like (VcAP1), CAULIFLOWER 1-like (VcCAL1), and FRUITFULL-like (VcFUL) genes were present and showed high similarity to their orthologues in herbaceous plants. Moreover, overexpression of VcFT promoted expression of all of these VcFT downstream genes. These results suggest that VcFT's down-stream genes appear conserved in blueberry.
Plant Biotechnology Resource and Outreach Center, Department of Horticulture, Michigan State University, East Lansing, Michigan, United States of America.
Aaron E
AE
Walworth
Center for Microbial Ecology, Michigan State University, East Lansing, Michigan, United States of America.
Benli
B
Chai
Plant Biotechnology Resource and Outreach Center, Department of Horticulture, Michigan State University, East Lansing, Michigan, United States of America.
Guo-Qing
GQ
Song
D029798:Blueberry Plants / Q000235:genetics*; D035264:Flowers / Q000235:genetics*; D020869:Gene Expression Profiling / Q000379:methods*; D018506:Gene Expression Regulation, Plant; D053263:Gene Regulatory Networks; D026161:MADS Domain Proteins / Q000235:genetics*; D018515:Plant Leaves / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics; D017423:Sequence Analysis, RNA
D026161:MADS Domain Proteins; D010940:Plant Proteins