The use of heterosis has greatly increased the yield of crops. It is a milestone event in the history of plant breeding and has made great contributions to solving the food crisis. Chinese cabbage is the vegetable crop with the largest cultivation area in my country, and it is the main dish of urban and rural residents. High-yield, high-quality, and disease resistance have always been important target traits for breeding. Chinese cabbage is a typical cross-pollinated crop, and its heterosis is very significant. Analyzing the molecular basis of the formation of Chinese cabbage heterosis has important reference value for the molecular improvement of Chinese cabbage yield and stress resistance.
Recently, Horticulture Research published an online report entitled Genome-wide analysis of changes in miRNA forbid target gene expression reveals key roles in the Cabbage Research Group of Vegetable Center. in heterosis for Chinese cabbage biomass, this research conducted microRNA (miRNA), transcriptome and degradome analysis of”Beijing New No. 3″ and its parents, revealing the key miRNAs and targets of Chinese cabbage biomass heterosis To regulatory genes.
”Beijing New No. 3″ is a first-generation hybrid of autumn-sown Chinese cabbage launched by the Vegetable Center in the 1990s. Due to its outstanding heterogeneity, it has been occupying the market for more than 20 years. The dominant position of Chinese cabbage planted in autumn in my country is an ideal material for studying the heterosis of Chinese cabbage. The project team used”Beijing New No. 3″ and its parents as materials, and selected four time points:the seedling stage, the rosette stage, the pericardium stage, and the mature stage to compare the growth and development status of the plants and the changes in biomass. The study found that the correlation between leaf weight and biomass of Dabai menu was the most significant, and the heterosis of biomass-related indicators throughout the growth period was very significant (Figure 1).
Then, the project team selected the seedling stage and the pericardial stage to analyze the difference between miRNA and transcriptome of”Beijing New No. 3″ and its parents, and passed the degradation group Sequencing verified the targeted regulatory genes of differentially expressed miRNAs. The study found that the expression level of most miRNAs in F1 hybrids was lower than the median parental value (MPV), and the target genes of the differential miRNAs were identified through degradome sequencing. For example, the target genes of bra-miR396 and bra-miR5722 are growth regulatory factor (GRF) and light harvesting protein gene (LHCB), respectively, which are involved in leaf development and photosynthesis. Gene enrichment analysis showed that the target genes of MPV-DEMs were significantly enriched in leaf morphogenesis, leaf shape and leaf development. Transcriptome analysis showed that, compared with the parent, the expression level of the differential gene related to photosynthesis and chlorophyll synthesis (MPV-DEG) in F1 hybrids was significantly increased, resulting in an increase in the photosynthesis capacity and chlorophyll content of F1 hybrids. Finally, we overexpressed bra-miR396 and its target gene BrGRF4.2 in Arabidopsis thaliana, proving that both play a crucial role in the formation of Chinese cabbage heterosis (Figure 2). The results of this study have important guiding significance for the utilization of Chinese cabbage heterosis and high-yield breeding.
Dr. Peirong Li from the Cabbage Research Group of the Vegetable Center is the first author of the paper. Researchers Yu Shuancang and Researcher Zhang Fenglan are the co-corresponding authors. The research was funded by the National Key Research and Development Program, the Outstanding Scientist Cultivation Program of the Beijing Academy of Agriculture and Forestry Sciences, the Collaborative Innovation Center for Genome Breeding, and the National Natural Science Foundation of China. In recent years, the research team has aimed to improve the yield, disease resistance and stress resistance of cabbage varieties. Based on genomics, domestication selection analysis and map-based cloning, a batch of control cabbage flowering, disease resistance and morphogenesis have been identified. Related functional genes, research results have been published in Molecular Plant, Plant Biotechnology Journal, Plant Cell forbid Environment, Journal of Experimental Botany and other journals.