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This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Abstract Heterosis or hybrid vigor describes a phenomenon that superior phenotypes compared to the two parents are observed in the heterozygous F 1 -hybrid plants. Identification and characterization of heterosis-related genes (HRGs) will facilitate hybrid breeding in crops. To identify HRGs in Brassica rapa, we analyzed transcriptome profiling using a Br300K microarray in non-heading Chinese cabbage at three developmental stages. A large number of genes were differentially expressed in F 1 hybrids and non-additive expression was prominent. Genes that are expressed specifically for F 1 hybrid at all three stages were Brassica-specific uncharacterized genes and several defense-related genes. Expression of several photosynthesis-and stress-related genes were also F 1 hybrid-specific. Thirteen NBS-LRR class genes showed high and specific expression in F 1 hybrid Shulu: some of them were characterized as defense genes in Arabidopsis, but most have not been. Further characterization of these defense-related genes in Brassica species and its application will be helpful for understanding the role of defense responses in heterosis. In addition, results obtained in this study will be valuable to develop molecular markers for heterosis and disease resistance in B. rapa.

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. BrCOLs, were expressed with paralog-specific pattern depending on flowering phenotypes: i.e., BrFLC1 and BrFLC2, major floral repressors, were expressed in Chiifu, BrFLCL/BrFLC5 in RCBr and BrFLC3 in both plants. The expression of several flowering repressing genes was gradually decreased in RCBr growth, but increased in Chiifu growth. However, the expression of genes involved in photoperiodic flowering was no difference between these two plants under LD and SD conditions, indicating photoperiodic pathway is not major factor to distinguish fast vs. slow flowering in B. rapa. The mechanism underlined in the rapid or fast flowering of RCBr would be further elucidated in association with the controlling mechanism of its short life span.