Associations of Two Polymorphic Loci: A HinfⅠLocus of the Porcine Subunit C of Succinate Dehydrogenase Complex (SDHC) Gene and A MspⅠLocus of the Porcine Rod cGMP-Phosphodiesterase γ-Subunit (PDE6G) Gene

A Hinf I locus of the porcine subunit C of succinate dehydrogenase complex (SDHC) gene and a Msp I locus of the porcine rod cGMP-phosphodiesterase γ-subunit (PDE6G) gene had been reported before, but the association analysis between the different genotypes and the traits had not been done. 300 Large White × Meishan F2 pigs were used as experimental materials to performe the PCR-RFLP analysis and association analysis for the two loci, results revealed that the polymorphism of the porcine subunit C of succinate dehydrogenase complex (SDHC) gene was significantly associated with the traits which included the carcass length, the estimated lean meat percentage, the estimated backfat thickness at last rib, the estimated backfat thickness at last 3-4th rib, the fat meat weight, the fat meat percentage, the lean meat weight,the lean meat percentage, the ratio of lean meat to fat meat, the leaf fat weight, the backfat thickness at shoulder, the backfat thickness at thorax-Waist, the backfat thickness at 6-7th thorax and the average daily gain. Seven other traits, the meat color value (Biceps femoris, BF), the meat marbling (Biceps femoris, BF), the water moisture (Longissimus dorsi, LD),the bone weight, the bone percentage, the loin eye width and the loin eye area, were found to be significantly correlated with the polymorphism of the porcine rod cGMP-phosphodiesterase γ-subunit (PDE6G) gene. Based on these results, it is necessary to apply the two genes as candidate genes to marker assistant selection (MAS) in pig breeding.     

Myristic Acid （MA） Promotes Adipogenic Gene Expression and the Differentiation of Porcine Intramuscular Adipocyte Precursor Cells

Intramuscular fat （IMF） content is considered to be a key factor that affects the marbling, tenderness, juiciness and lfavor of pork. To investigate the effects of myristic acid （MA） on the differentiation of porcine intramuscular adipocytes, cells were isolated from longissimus dorsi muscle （LDM） and treated with 0, 10, 50 or 100μmol L-1 MA. The results showed that MA signiifcantly promotes the differentiation of intramuscular adipocytes in a dose-dependent manner. MA also led to a parallel increase in the expression of peroxisome proliferator activated receptor-γ（PPARγ） and adipose-related genes, such as glucose transporter 1 （GLUT1）, lipoprotein lipase （LPL）, adipocyte fatty acid binding protein 4 （FABP4/aP2）, fatty acid translocase （FAT）, acetyl-CoA carboxylaseα（ACCα）, adipose triglyceride lipase （ATGL） and fatty acid synthase （FASN）. However, no signiifcant effects of MA were observed on the expression of CAAT enhancer binding protein-α（C/EBPα） or hormone sensitive lipase （HSL）. The expression of pyruvate dehydrogenase kinase 4 （PDK4） was increased by MA during the early stages of differentiation （day 1-3）. In addition, MA also increased the absolute content of C14 （P〈0.001） and saturated fatty acids （SFA） （P〈0.05） to varying degrees, but no effects were observed on other fatty acids. These results suggest that MA might be able to enhance the IMF content of pork and increase the accumulation of myristic and myristoleic acid in muscle, which might have beneifcial implications for human health.     

Sequencing, Polymorphism and Expression Profile Analysis of Porcine Hexokinase Ⅱ （HK2） Gene

Hexokinase Ⅱ has been demonstrated to play the role of a key enzyme member in the glycolysis reaction. It catalyzes the conversion of glucose to glucose-6-phosphate, thus committing glucose to the glycolytic pathway. In this paper, the partial exons and introns 10, 11, 13 and 14 of the porcine HK2 gene were cloned and sequenced by comparative genomics. Comparative sequencing of three pig breeds revealed ten putative single-nucleotide polymorphisms （SNPs）, one of which in intron 10 with differing bases （G981A） is within the restriction site for enzyme Msp I. Distribution of Msp I -RFLP genotype and allele frequencies among different pig breeds were studied. By association analysis between Msp I PCR- RFLP polymorphism （AA, AB, BB genotypes of HK2 gene intron 10） and some meat quality and carcass traits in F2 group, which was constructed by our laboratory, a significant difference of pig average backfat at rump was found between AB and BB genotypes （P〈0 05） in F2 group. In addition, the pattern of expression of ilK2 in a variety of tissues in pig was also determined using semi-quantitative RT-PCR. The expression of HK2 mRNA was detected only in pig skeletal muscle.     

Major Gene Identification and Quantitative Trait Locus Mapping for Yield- Related Traits in Upland Cotton （Gossypium hirsutum L.）

Segregation analysis of the mixed genetic model of major gene plus polygene was used to identify the major genes for cotton yield-related traits using six generations P1, P2, F1, B1, B2, and F2 generated from the cross of Baimian 1 x TM-1. In addition to boll size and seed index, the major genes for the other five traits were detected： one each for seed yield, lint percentage, boll number, lint index; and two for lint yield. Quantitative trait locus/loci （QTL） mapping was performed in the F2 and F2：3 populations of above cross through molecular marker technology, and a total of 50 QTL （26 suggestive and 24 significant） for yield-related traits were detected. Four common QTL were discovered： qLP-3b（F2）/qLP-3（F2：3） and qLP-19b （F2）/qLP-19（F2：3） for lint percentage, qBN-17（F2）/qBN-17（F2：3） for boll number, and qBS-26b（F2）/qBS-26（F2：3） for boll size. Especially, qLP- 3b（Fz）/qLP-3（F2：3）, not only had LOD scores 〉3 but also exceeded the permutation threshold （5.13 and 5.29, respectively）, correspondingly explaining 23.47 and 29.55% of phenotypic variation. This QTL should be considered preferentially in marker assisted selection （MAS）. Segregation analysis and QTL mapping could mutually complement and verify, which provides a theoretical basis for genetic improvement of cotton yield-related traits by using major genes （QTL）.     

Identification of Molecular Markers Linked to the Wilt Resistance Gene FuJ7（t） in Flax

A cross between wilt resistant flax variety Jinya7 and susceptible variety Jinyal was made for mapping wilt resistance gene(s). The inoculation test of F1 and F2 progeny proved that the resistance of Jinya7 to wilt is controlled by two dominant genes. With 48 EcoRⅠ /MseⅠ primer combinations, amplified fragment length polymorphisms (AFLP) analysis was performed on two parents and their F2 resistance and susceptibility bulks. A total of about 3 300 distinguishable bands were amplified, of which three bands had stable differences. The genetic linkage analysis of the three polymorphic DNA fragments with the resistance gene(s) was made in the F2 segregating population derived from the cross between Jinya7 and Jinyal. The DNA fragment AG/CAG was found closely linked to one of the wilt-resistant genes, which with a genetic distance of 5.2cm, was tentatively named FuJ7(t). The cloned fragment AG/CAG was sequenced and then converted successfully to a sequence characterized amplified region (SCAR) marker, which can be used more conveniently in the identification and marker-assisted selection for the wilt resistance gene FuJ7(t) to flax wilt.     

Characterization of Porcine Matrix Metalloproteinase 23 （pMMP-23） Gene and Its Association with Litter Size Traits

The matrix metalloproteinase 23 (MMP-23), which might play a role in ovulation in mammals, was one of the promising candidate genes for litter size traits in pigs. In the present research, partial sequence of porcine MMP-23 (pMMP-23) gene, including exons 2-8 (GenBank: EU360790), was obtained. Real-time PCR analysis revealed that pMMP-23 gene was highly expressed in ovary. PCR-Sau3A I-RFLP and PCR-Acc II-RFLP assay were established to detect a C/T mutation in exon 3 (EU360790: g. 269C>T) and an A/G mutation in exon 4 (EU360790: g. 505A>G), respectively. Association study for these two SNPs with litter size was assessed in three independent populations (Minzhu, Landrace I and Landrace II). Statistical analysis demonstrated that for second and subsequent litters, TT sows produced more TNB than CC pigs in Landrace breed (P<0.05) at g. 269C>T locus, and the additive effect was significant (P<0.05); GG sows produced more TNB and NBA than AA pigs in Minzhu (P<0.01) and Landrace breeds (P<0.05) at g. 505A>G locus, and the additive effect was significant (P<0.01 or P<0.05). Our study suggested that the pMMP-23 gene might be a novel candidate gene for litter size traits, and g. 505A>G locus might be a useful molecular marker for marker assisted selection (MAS).     

Identification and Expression Analysis of the Phosphoenolpyruvate Carboxylase Gene Family in Peanut （Arachis hypogaea L.）

Phosphoenolpyruvate carboxylase （PEPC） is widely distributed in plants and bacteria, and catalyzes the carboxylation of phosphoenolpyruvate to form oxaloacetate and inorganic phosphate. To investigate the molecular mechanisms of the regulation and control of peanut oil, with the degenerated primers and RACE-PCR approach, five PEPC genes were cloned from peanut, and designated as AhPEPC1, AhPEPC2, AhPEPC3, AhPEPC4, and AhPEPC5, respectively. The structure and phylogenetic analysis of PEPC protein indicated that AhPEPC1-4 genes encoded a typical plant-type PEPC-enzyme, and AhPEPC5 a bacterial-type. By real-time quantitative RT-PCR approach the expression pattern of each gene was detected in various tissues of normal and high oil-content peanut varieties. It was found that there was a lower expression level of AhPEPCs genes except for the AhPEPC2 in high-oil peanut than normal-oil peanut line. The results provide some fundamental information for the further investigation of plant PEPC proteins and their role in regulation of oil-content in peanut seeds.     

Long Chain Acyl-Coenzyme A Synthetase 4 （BnLACS4） Gene from Brassica napus Enhances the Yeast Lipid Contents

Long-chain acyl-Coenzyme A （CoA） synthetases （LACSs） catalyze the formation of long-chain acyl-CoA, and play important roles in fatty acid metabolism including phospholipids, triacylglycerol （TAG） biosynthesis and fatty acid 13-oxidation. Here, we report the characterization of a LACS gene from Brassica napus. It is highly homologous to Arabidopsis LACS4 and thus designated as BnLACS4. The cloned gene BnLACS4 could complement a LACS-deficient yeast strain YB525. It is mainly expressed in flowers and developing seeds where lipid biosynthesis is at high rate in Brassiea napus. When transiently expressed in tobacco leaves, BnLACS4 is localized in endoplasmic reticulum （ER）, the common site for eukaryotic pathway of lipid biosynthesis. Expression of BnLACS4 in the yeast strain pep4 increased its lipid content. Taken together, our results suggest that BnLACS4 may be involved in lipid biosynthesis in B. napus.     

Chromosomal Location of the Genes Associated with Photosynthesis of Lophopyrum elongatum （Host） A.Loeve in Chinese Spring Background

Researches on the relationship between photosynthesis and wheat yield have equally attracted the attention of both domestic and overseas scholars. No report has existed so far on the study of the effects of exogenous chromosomes on photosynthesis using the substitution series as materials. In this research, Triticum aestivum cv. Chinese Spring-Lophopyrum elongatum （Host） A.Loeve disomic substitution series were used as materials and flag leaves as the measuring position. And the CI-310 Portable Photosynthesis System made by CID Co. in USA was used to measure the net rate of photosynthesis of flag leaves in different developing stages and also to correlate photosynthesis with yield. Results showed that, out of the whole developing stages, at the anthesis stage the line of DS2Ee （2A） had the highest photosynthetic rate, therefore it could be used in improving process of the character of kernel number. The flag leaves of DS4Ee （4A, 4B, 4D） lines demonstrated certain high net photosynthetic rate from heading to grain filling stage, so it is valuable in the researh of promoting the yield index like 1 000-grain weight through improvement of the photosynthetic rate at grain filling stage.     

Cloning of TaCYP707A 1 Gene that Encodes ABA 8′-Hydroxylase in Common Wheat（Triticum aestivum L.）

The plant hormone abscisic acid （ABA） regulates many important physiological and developmental processes in plants. The objective of this study was to clone the ABA 8′-hydroxylase gene in common wheat. In the present study, we used the eDNA sequence of barley HvCYP707A1 gene （GenBank accession no. AB239299） as a probe for BLAST search against the common wheat （Triticum aestivum L.） EST database in GenBank. All wheat ESTs sharing high similarity with the reference gene were subjected to contig assembly. Primers were designed based on the constructed contigs to clone the wheat CYP707A1 gene, designated as TaCYP707A1. The genomic DNA sequence of TaCYPTO7A1 gene comprised five exons and four introns, with a size of 2225 bp. The corresponding cDNA sequence of TaCYP707A1 was 1737 bp, containing an open reading frame （ORF） of 1431 bp, a 42-bp 5′-untranslated region （UTR） and a 264-bp 3′UTR, with 94.9% of identical sequences to HvCYP707A1 gene （AB239299）. The neighbor joining tree indicated that the deduced amino acid sequences of TaCYP707A1 gene was highly similar to those of barley and rice. The TaCYP707A1 gene was located on chromosome 6BL using a set of Chinese Spring nullisomic-tetrasomic lines and ditelosomic line 6BS. These results will be of high importance in understanding of molecular mechanism of ABA catabolism.