Heterosis is most frequently manifested by the substantially increased vigorous growth of hybrids compared with their parents. Investigating genomic variations in natural populations is essential to understand the initial molecular mechanisms underlying heterosis in plants. Here, we characterized the genomic architecture associated with biomass heterosis in 200Arabidopsishybrids. The genome-wide heterozygosity of hybrids makes a limited contribution to biomass heterosis, and no locus shows an obvious overdominance effect in hybrids. However, the accumulation of significant genetic loci identified in genome-wide association studies (GWAS) in hybrids strongly correlates with better-parent heterosis (BPH). Candidate genes for biomass BPH fall into diverse biological functions, including cellular, metabolic, and developmental processes and stimulus-responsive pathways. Important heterosis candidates includeWUSCHEL,ARGOS, and some genes that encode key factors involved in cell cycle regulation. Interestingly, transcriptomic analyses in representativeArabidopsishybrid combinations reveal that heterosis candidate genes are functionally enriched in stimulus-responsive pathways, including responses to biotic and abiotic stimuli and immune responses. In addition, stimulus-responsive genes are repressed to low-parent levels in hybrids with high BPH, whereas middle-parent expression patterns are exhibited in hybrids with no BPH. Our study reveals a genomic architecture for understanding the molecular mechanisms of biomass heterosis inArabidopsis, in which the accumulation of the superior alleles of genes involved in metabolic and cellular processes improve the development and growth of hybrids, whereas the overall repressed expression of stimulus-responsive genes prioritizes growth over responding to environmental stimuli in hybrids under normal conditions.
Although green light (GL, 500–600 nm) occupies half the visible light spectrum and regulates a series of plant developmental processes, the mechanism by which GL regulates seedling morphogenesis is enigmatic. Here, we reported that pure GL (500–600 nm, λmax, 527 nm) promoted the cotyledon development of Arabidopsis seedlings through phytochrome B (phyB). Genetic analysis indicated that phyB was involved in cotyledon development under continuous GL. Compared with red light (RL), GL induced phyB translocation from the cytoplasm to the nucleus and speckle-like photobody formation with a slower rate, which was reversed by far red light. Further transcriptomic data demonstrated that phyB participated in GL-responsive transcriptional networks in concert with four PHYTOCHROME-INTERACTING FACTORS (PIFs, PIF1, PIF3, PIF4, and PIF5). As expected, protein levels of the PIFs were decreased by GL. Similar to RL, GL induced the rapid degradation of PIF3 in a phy-dependent manner. Our results suggest that pure GL (527 nm) leads to the migration of phyB into the nucleus to trigger photomorphogenesis by possibly promoting the degradation of PIFs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.