Acta Genetica Sinica最新文献

Seed size is one of the important factors of soybean [Glycine max (L.) Merrill] yield. There have been lots of reports about genetic effects and physiology—ecological researches on seed size, but the genetic behaviors of genes during seeds development were rarely discussed. Analysis of main genetic effects for fresh seed size (FSS) and dry seed size (DSS) of soybean was conducted with diallel cross data by using a seed genetic model. Analyses of unconditional and conditional variances and correlations were used to evaluate the developmental behavior of soybean. The phenotypic means of FSS and DSS in soybean at eight stages among three generations reached the highest value at 9/6 and 9/13, respectively. The means of FSS decreased dramatically after 9/6, but the means of DSS maintained relatively stable tendency at corresponding periods. The unconditional variance analysis showed that FSS and DSS were controlled by embryo, cytoplasmic and maternal effects in the whole growth period. Genetic effects due to cytoplasmic and maternal effects were relatively important for FSS and DSS at most of the growth periods. Conditional variance analysis showed that genes from different genetic system expressed discontinuously in the whole growth period. The net genetic effects due to cytoplasmic and maternal plant on FSS and DSS were larger than those of embryo effects at most of the growth periods. Different genetic system can affect the relationship of various stages to mature solely or simultaneously. Embryo additive effects at 8/16, embryo dominance effects at 8/9 and 8/16, maternal plant dominance effects at 8/2 and 8/16 could ultimately affect the performance of FSS at maturing stage. Embryo additive effects at 8/2 and 9/13, cytoplasm effects at 8/9, maternal plant dominance effects at 8/2 could ultimately affect the performance of DSS.

The genetic diversity of 43 sources of Upland cotton germplasm with different parental origins, breeding periods, and ecological growing areas in China were studied on the basis of simple sequence repeat (SSR) markers. A total of 130 gene alleles with 80% polymorphism were detected from 36 SSR primers. The number of alleles per primer ranged from two to eight with an average of 3.6. The polymorphism information content (PIC) range was 0.278–0.865, with an average of 0.62. The average genotype diversity index (H') was 1.102, the highest was 2.039 and the lowest was 0.451. The average coefficient of the genetic similarity of SSR markers among source germplasm was 0.610, ranging from 0.409 to 0.865. These indicated that the genetic diversity at the genomic level of the selected source germplasm was rich, and was representative of the diversity of the germplasms, in general. The diversity at the genome level of the base germplasm from the second and third breeding periods was decreased compared to that of the first period, indicating that the cotton genetic background in China became narrow gradually. The diversity of SSR markers among the base germplasm from early maturity cotton growing areas in the north was higher than those from the Huanghe and Yangtze growing areas. The molecular marker genetic similarity index of the domestic varieties was higher than that in the introduced varieties, which indicates that the genetic diversity in domestic cultivars was lower than that in the introduced varieties. This study gives an overview of the genetic diversity of the cotton germplasm base in China, and provides a guide for breeders to develop new cultivars efficiently.

Rice is known to be one of the most important crops for human consumption. As the model cereal crop, large-scale sequencing of rice genome must play quite important roles both in theoretical research and practical application in rice breeding, which announces the opening of another new way to resolve the world food crisis. At present, the emphasis of rice genome research has been transferred from structure genomics to functional analysis. The discovery of new genes and annotation of gene function was believed to be an important issue in functional genomics research. In this article, the sequencing and functional research of the rice genome were reviewed. These results may provide some useful clues for rice genetic engineering and breeding practices.

The 5-lipoxygenase activating protein, an important regulator in the biosynthesis of proinflammatory leukotrienes, has been reported to confer risks for cardiovascular diseases and stroke. The purpose of this study is to assess whether genetic variants in the ALOX5AP encoding the 5-lipoxygenase activating protein will influence the risk for stroke in the Chinese population. A total of 1 773 patients with stroke and 1 713 controls were recruited from seven clinical centers. Polymorphisms of SG13S114T/A and SG13S89G/A in the ALOX5AP were genotyped by the polymerase chain reaction and the restriction enzyme analysis. The multivariate logistic regression model was used to exclude the influence of the conventional vascular risk factors on stroke. The frequency of SG13S114A allele in the ALOX5AP was significantly higher in male patients with thrombotic stroke (33.6%) than in controls (29.2%; P=0.014). The SG13S114AA genotype was significantly associated with a 1.62-fold risk for thrombotic stroke in men (95% confidence interval, 1.11 to 2.35; P=0.012). The SG13S89G/A variant was not associated with stroke or its subtypes. Haplotype analysis showed no significant differences between stroke patients and controls. The present study suggested that a common genetic variant SG13S114T/A in the ALOX5AP gene is associated with an increased risk for atherothrombotic stroke in Chinese males, and racial differences in allele and genotype frequencies may account partially for the different association findings between populations.

The first and second internal transcribed spacer (ITS1 and ITS2) regions of the ribosomal DNA from four species, Meretrix meretrix L., Cyclina sinensis G., Mercenaria mercenaria L., and Protothaca jedoensis L., belonging to the family Veneridae were amplified by PCR and sequenced. The size of the ITS1 PCR amplification product ranged from 663 bp to 978 bp, with GC contents ranging from 60.78% to 64.97%. The size of the ITS1 sequence ranged from 585 bp to 900 bp, which is the largest range reported thus far in bivalve species, with GC contents ranging from 61.03% to 65.62%. The size of the ITS2 PCR amplification product ranged from 513 bp to 644 bp, with GC contents ranging from 61.29% to 62.73%. The size of the ITS2 sequence ranged from 281 bp to 412 bp, with GC contents ranging from 65.21% to 67.87%. Extensive sequence variation and obvious length polymorphisms were noted for both regions in these species, and sequence similarity of ITS2 was higher than that of ITS1 across species. The complete sequences of 5.8S ribosomal RNA gene were obtained by assembling ITS1 and ITS2 sequences, and the sequence length in all species was 157 bp. The phylogenetic tree of Veneridae clams was reconstructed using ITS2-containing partial sequences of both 5.8S and 28S ribosomal DNA as markers and the corresponding sequence information in Arctica islandica as the outgroup. Tree topologies indicated that P. jedoensis shared a close relationship with M. mercenaria and C. sinensis, a distant relationship with other species.

In this study, the full-length cDNA of porcine liver-type fatty acid binding protein gene (L-FABP) was obtained by the rapid amplification of cDNA ends (RACE). The nucleotide sequence and the predicted protein sequence share a high sequence identity with their mammalian counterparts. Semi-quantitative RT-PCR revealed that porcine L-FABP gene is expressed in all twelve tissues studied, but a transcript is more abundant in liver and small intestine than in other tissues. The part genomic DNA of the porcine L-FABP gene was amplified by PCR. The coding region of the pig L-FABP gene is organized in four exons and spans an approximate 2.62 kb genomic region. Comparative sequencing of four pig breeds revealed a C→T single nucleotide polymorphism (SNP) within exon 2. The allele and genotype frequencies differed significantly between indigenous Chinese Zang, Dahe, and Yanan pigs with higher frequencies of allele C and genotype CC and Yorkshire pigs with higher frequencies of allele T and genotype TT (P < 0.01). The association analysis suggested that the C<T polymorphism was associated with intramuscular fat content, indicating that the SNP is a potential molecular marker for intramuscular fat content.

On the basis of a JA-inducible EST, the full length cDNA of a putative protein kinase gene, OsSJMK1, was isolated from rice (Oryza sativa L.). The predicted protein of this gene, consisting of 498 amino acids with a predicted PI value of 8.43, contains a mitogen-activated protein kinase (MAPK) domain with a dual-phosphorylation activation motif TDY (Thr-Asp-Tyr) and a C-terminus domain that feature a typical MAPK belonging to subgroup V, OsSJMK1 showed 81% sequence identity to the reported BWMK1, a blast fungus and wounding inducible protein, in the N-terminus kinase domain but had low sequence identity in the C-terminus domain. Despite the high similarity of gene structure between OsSJMK1 and BWMK1, the expression of OsSJMK1 was weakly induced by blast fungus but not wounding, rather it was transiently induced by jasmonic acid (JA) and salicylic acid (SA) at early stages of treatment. This gene was not induced by other hormones (such as ABA) or abiotic stresses, such as drought and salinity. The low level of transcript of this gene was detected in the various tissues of rice. The results suggest that OsSJMK1 might be activated specifically by JA and SA and involved in defense signaling pathways.

A new double-haploid (rdh) rice plant with purple stigma and red seeds was discovered by tissue culture. Genetic analysis suggested that the trait of rdh purple stigma was controlled by a pair of dominant gene. Polymorphic analysis of microsatellite markers demonstrated that the purple stigma gene of rdh was located on rice chromosome 6 at 4.2 cM, 0.35 cM and 0.53 cM from microsatellite markers RM276, RM253 and RM111, respectively. It was believed that the purple stigma gene of rdh was the first mapped purple stigma gene on rice chromosome 6. This purple stigma gene was designated tentatively as Ps-4.

Relative tillering ability, available spike, biomass, and grain yield of P₁, P₂, F₁ and F_2,3 were used to study the genetic development of rice related to phosphorus efficiency with a quantitative genetic model. The results indicated that under a low-P condition, the relative tillering ability and the relative available spike were apt to the additivity-dominance-epistasis model with two couples of major genes, between which additive, dominant and epistatic effects existed, and with multi-gene modifications. Their maximum major gene effect mostly indicated additivity, but sub-maximum major gene effect mostly indicated dominance. Relative biomass and grain yield were apt to the additivity-dominance-epistasis and multi-genes model. The heritabilities of the major genes were 60.08% and 37.70%, and those of the multi-genes were 32.15% and 58.9%, respectively. This meant that the heritabilities of the relative tillering ability, the relative available spike, and the relative biomass were high, so they were ideal indexes for rice breeding tolerating to low-P stress; whereas, the heritability of the relative grain yield was low, which meant that the grain yield was easily affected by the environment.

Type 2 diabetes mellitus (T2DM) is a complex disease characterized by hyperglycemia, insulin resistance, and impaired insulin secretion. T2DM is under strong genetic control. Identification and characterization of genes involved in determining T2DM will contribute to a greater understanding of the pathogenesis of T2DM, and ultimately might lead to the development of better diagnosis, prevention and treatment strategies. Efforts to identify T2DM susceptibility genes have focused on candidate gene approach (association studies) and genome-wide scans (linkage analyses). In this article, we review the current status for mapping and identification of genes for T2DM, with a focus on some promising regions (or genes) and future prospects.