RESUMO
Heterosis has greatly contributed to conventional plant breeding and is widely used to increase crop plant productivity. However, although some studies have explored the mechanisms of heterosis at the genomic and transcriptome level, these mechanisms still remain unclear. The growth and development of maize seedlings and immature embryos have an important impact on subsequent production. This study investigated differentially expressed genes (DEGs) between parents and reciprocal hybrids in the seedling leaves, roots, and immature embryo 15 days after pollination using amplified fragment length polymorphism (AFLP)-based transcript profiling (cDNA-AFLP). We isolated 180, 170, and 108 genes from the leaves, roots, and immature embryos, respectively, that were differentially expressed between hybrids and parents. Sequencing and functional analysis revealed that 107 transcript-derived fragments in the roots and leaves and 90 in the immature embryos were involved in known functions, whereas many DEGs had roles in plant growth and development, photosynthesis, signal transduction, and seed germination. Quantitative reverse-transcription polymerase chain reaction analysis of relative expression levels between reciprocal hybrids and both parental genotypes of selected genes produced results that were consistent with cDNA-AFLP. We validated the expression patterns of 15 selected genes related to heterosis formation and revealed that most showed non-additive expression in one or both hybrids, including dominant, underdominant, and overdominant expression. This indicates that gene-regulatory interactions among parental alleles play an important role in heterosis during the early developmental stages of maize.
Assuntos
Quimera , Perfilação da Expressão Gênica , Hibridização Genética , Transcriptoma , Zea mays/genética , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Germinação/genética , Vigor Híbrido/genética , Endogamia , Reprodutibilidade dos TestesRESUMO
Heterosis is the superior performance of heterozygous individuals and has been widely exploited in plant breeding, although the underlying regulatory mechanisms still remain largely elusive. To understand the molecular basis of heterosis in maize, in this study, roots and leaves at the seedling stage and embryos and endosperm tissues 15 days after fertilization of 2 elite hybrids and their parental lines were used to estimate the levels and patterns of cytosine methylation by the methylation-sensitive amplification polymorphism method. The relative total methylation levels were lower in all the tissues of all hybrids than their corresponding mid-parent values, and the number of demethylation events was higher in the hybrids. These results implied that the decreasing trend and demethylation in hybrids relative to their parents may enable the derepression and possibly expression of many genes that were associated with the phenotypic variation in hybrids. To further analyze the observed methylation pattern changes, a total of 63 differentially displayed DNA fragments were successfully sequenced. Basic Local Alignment Search Tool analysis showed that 11 fragments shared similarity with known functional proteins in maize or other plant species, including metabolism, transposon/retrotransposon, development, stress response, and signal transduction, which indicated that these genes might play a significant role in maize hybrid vigor.
Assuntos
Metilação de DNA , Regulação da Expressão Gênica de Plantas , Vigor Híbrido , Hibridização Genética , Zea mays/genética , EndogamiaRESUMO
Hu sheep is one of the most important species in China; it is also listed as one of the 78 nationally protected domestic animals by the Chinese government in 2000. The construction of cDNA expression library of Hu sheep is of great significance for protecting individual genomes, generating transgenic sheep, and conducting clinical research using cDNA from Hu sheep. In this study, the total RNA from the ear tissue of Hu sheep was extracted, and a cDNA expression library was constructed using the SMART(TM) technique. The titer of amplified cDNA library was 1.09 x 10(10) PFU/mL, the rate of recombination was above 91.6%, and the average size of fragments was 1.1 kb. This study has an important significance for the preservation of Hu sheep resources at the genome level.
Assuntos
DNA Complementar/genética , Espécies em Perigo de Extinção , Biblioteca Gênica , Ovinos/genética , Animais , China , Clonagem Molecular , Eletroforese em Gel de Ágar , RNA/genética , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
We examined the influence of the promoter polymorphisms -250G/A (rs2070895) and -514C/T (rs1800588) in the human hepatic lipase (LIPC) gene on dyslipidemia and hypertensive disorders complicating pregnancy (HDCP) in a Chinese population. Clinically defined HDCP patients (N = 321) and healthy pregnant women (N = 331) were recruited and genotyped using polymerase chain reaction-restriction fragment length polymorphism for the two LIPC single nucleotide polymorphisms (SNPs). The results showed significant relationships between HDCP and triglycerides, apolipoprotein A1, and high-density lipoprotein cholesterol (P < 0.05), which confirmed that HDCP was accompanied by dyslipidemia. The results also demonstrated that in gestational hypertension (GH) patients, both total cholesterol (TC) and systolic blood pressure (SBP) levels were related to the two SNPs (P ≤ 0.004), although no significant association was found between HDCP and LIPC genotypes or alleles. Significant linkage disequilibrium of the two SNPs was found in both HDCP patients (R(2) = 0.867) and controls (R(2) = 0.91). Body mass index (BMI) was associated with -250G/A in women with mild preeclampsia (MPE) (P = 0.01). Carriers of the mutant homozygote -250AA genotype presented higher BMI in the MPE group. In conclusion, the LIPC -250G/A and -514C/T variants influenced TC and SBP levels in GH patients and the BMI level in the MPE group, although there was no evidence to validate an association between HDCP and LIPC allele, genotype, or haplotype frequencies.