Orchidaceae, renowned for its spectacular flowers and other reproductive and ecological adaptations, is one of the most diverse plant families. Here we present the genome sequence of the tropical epiphytic orchid Phalaenopsis equestris, a frequently used parent species for orchid breeding. P. equestris is the first plant with crassulacean acid metabolism (CAM) for which the genome has been sequenced. Our assembled genome contains 29,431 predicted protein-coding genes. We find that contigs likely to be underassembled, owing to heterozygosity, are enriched for genes that might be involved in self-incompatibility pathways. We find evidence for an orchid-specific paleopolyploidy event that preceded the radiation of most orchid clades, and our results suggest that gene duplication might have contributed to the evolution of CAM photosynthesis in P. equestris. Finally, we find expanded and diversified families of MADS-box C/D-class, B-class AP3 and AGL6-class genes, which might contribute to the highly specialized morphology of orchid flowers
Our findings showed that H19 functions as a suppressor of NSCLC and plays an important role in the migration and invasion of NSCLC. More importantly, H19 may regulate NSCLC metastasis through modulating cellular signaling pathway proteins related to cell proliferation and cell adhesion, including MACC1, EGFR, β-catenin and ERK1/2. These results put forward our understanding of the detailed mechanism of H19 lncRNA regulating the process of NSCLC metastasis.
Genomes of potyviruses, the largest group of plant viruses, encode HC-Pro proteins that mediate RNA silencing suppression. HC-Pros may exhibit only 40% similarity between species, and induce different levels in autophagic ARGONAUTE1 (AGO1) degradation. Our data indicated that HC-Pro of turnip mosaic virus (HC-ProTu) could efficiently trigger AGO1 degradation through autophagy compared with HC-Pros of zucchini yellow mosaic virus (HC-ProZy) and tobacco etch virus (HC-ProTe). Furthermore, HC-ProTu, but not in HC-ProZy, forms a suppression body (S-body) to recruit AGO1 and HEN1, preventing those components from translocating into the nucleus. HC-ProTu, but not HC-ProZy and HC-ProTe, specifically inhibits HEN1 activity, resulting in unmethylated microRNAs (miRNAs) accumulating in the cytoplasm without loading into AGO1. Therefore, we hypothesize that HC-ProTu could enhance the autophagic AGO1 degradation due to the unique HEN1 inhibition interfering with RNA-inducing silencing complex (RISC) assembly.
With the growing demand for its ornamental uses, the African violet (Saintpaulia ionantha) has been popular owing to its variations in color, shape and its rapid responses to artificial selection. Wild type African violet (WT) is characterized by flowers with bilateral symmetry yet reversals showing radially symmetrical flowers such as dorsalized actinomorphic (DA) and ventralized actinomorphic (VA) peloria are common. Genetic crosses among WT, DA, and VA revealed that these floral symmetry transitions are likely to be controlled by three alleles at a single locus in which the levels of dominance are in a hierarchical fashion. To investigate whether the floral symmetry gene was responsible for these reversals, orthologs of CYCLOIDEA (CYC) were isolated and their expressions correlated to floral symmetry transitions. Quantitative RT-PCR and in situ results indicated that dorsal-specific SiCYC1s expression in WT S. ionantha (SCYC1A and SiCYC1B) shifted in DA with a heterotopically extended expression to all petals, but in VA, SiCYC1s' dorsally specific expressions were greatly reduced. Selection signature analysis revealed that the major high-expressed copy of SCYC1A had been constrained under purifying selection, whereas the low-expressed helper SiCYC1B appeared to be relaxed under purifying selection after the duplication into SCYC1A and SiCYC1B. Heterologous expression of SCYC1A in Arabdiopsis showed petal growth retardation which was attributed to limited cell proliferation. While expression shifts of SCYC1A and SiCYC1B correlate perfectly to the resulting symmetry phenotype transitions in F1s of WT and DA, there is no certain allelic combination of inherited SiCYC1s associated with specific symmetry phenotypes. This floral transition indicates that although the expression shifts of SCYC1A/1B are responsible for the two contrasting actinomorphic reversals in African violet, they are likely to be controlled by upstream trans-acting factors or epigenetic regulations.
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