The Characterization of the Key Aroma Compounds in Non-Smoked Bacon by Instrumental and Sensory Methods

The aroma profiles in non-smoked bacon were investigated via GC-O-MS, GC × GC-TOFMS, and GC-IMS. GC-O-MS is advantageous for detecting aldehydes. GC × GC-TOFMS is more sensitive to hydrocarbons and alcohols, while GC-IMS detects a balanced range of categories. Only 9 of the 239 detected volatiles were identifiable by all three methods. Therefore, the combination of all three methods proved to be the most effective way to comprehensively analyze the aroma profiles of bacon. Recombination and omission tests were performed using aroma compounds with a flavor dilution (FD) factor greater than 27; five volatiles were identified as key aroma compounds in non-smoked bacon, including hexanal, (E,E)-2,4-decadienal, 1-octen-3-ol, dihydro-5-pentyl-2(3H)-furanone, and 3-methyl-butanoic acid. Among these, hexanal and 1-octen-3-ol exhibited relatively high FD factors and odor activity values (OAVs), so they were confirmed as the primary contributors. Meanwhile, seven volatiles contributed to the unique aroma of non-smoked bacon in different regions. The difference in the aroma of bacon in different regions is mainly due to the content of various volatiles rather than the type. A comprehensive analysis of the aroma in non-smoked bacon can reveal theoretical information for improving the process and quality control of the product.

Construction of Genetic Map and QTL Mapping for Seed Size and Quality Traits in Soybean (Glycine max L.)

Soybean (Glycine max L.) is the main source of vegetable protein and edible oil for humans, with an average content of about 40% crude protein and 20% crude fat. Soybean yield and quality traits are mostly quantitative traits controlled by multiple genes. The quantitative trait loci (QTL) mapping for yield and quality traits, as well as for the identification of mining-related candidate genes, is of great significance for the molecular breeding and understanding the genetic mechanism. In this study, 186 individual plants of the F2 generation derived from crosses between Changjiangchun 2 and Yushuxian 2 were selected as the mapping population to construct a molecular genetic linkage map. A genetic map containing 445 SSR markers with an average distance of 5.3 cM and a total length of 2375.6 cM was obtained. Based on constructed genetic map, 11 traits including hundred-seed weight (HSW), seed length (SL), seed width (SW), seed length-to-width ratio (SLW), oil content (OIL), protein content (PRO), oleic acid (OA), linoleic acid (LA), linolenic acid (LNA), palmitic acid (PA), stearic acid (SA) of yield and quality were detected by the multiple- d size traits and 113 QTLs related to quality were detected by the multiple QTL model (MQM) mapping method across generations F2, F2:3, F2:4, and F2:5. A total of 71 QTLs related to seed size traits and 113 QTLs related to quality traits were obtained in four generations. With those QTLs, 19 clusters for seed size traits and 20 QTL clusters for quality traits were summarized. Two promising clusters, one related to seed size traits and the other to quality traits, have been identified. The cluster associated with seed size traits spans from position 27876712 to 29009783 on Chromosome 16, while the cluster linked to quality traits spans from position 12575403 to 13875138 on Chromosome 6. Within these intervals, a reference genome of William82 was used for gene searching. A total of 36 candidate genes that may be involved in the regulation of soybean seed size and quality were screened by gene functional annotation and GO enrichment analysis. The results will lay the theoretical and technical foundation for molecularly assisted breeding in soybean.

Characterization analysis of Rongchang pig population based on the Zhongxin-1 Porcine Breeding Array PLUS

OBJECTIVE

To carry out a comprehensive production planning of the existing Rongchang pig population from both environmental and genetic aspects, and to establish a closed population with stable genetic diversity and strict pathogen control, it is necessary to fully understand the genetic background of the population.

METHODS

We genotyped 54 specific pathogen free (SPF) Rongchang pigs using the Zhongxin-1 Porcine Breeding Array PLUS, calculated their genetic diversity parameters and constructed their families. In addition, we also counted the runs of homozygosity (ROH) of each individual and calculated the value of inbreeding coefficient based on ROH for each individual.

RESULTS

Firstly, the results of genetic diversity analysis showed that the effective population size (Ne) of this population was 3.2, proportion of polymorphic markers (PN) was 0.515, desired heterozygosity (He) and observed heterozygosity (Ho) were 0.315 and 0.335. Ho was higher than He, indicating that the heterozygosity of all the selected loci was high. Secondly, combining the results of genomic relatedness analysis and cluster analysis, it was found that the existing Rongchang pig population could be divided into four families. Finally, we also counted the ROH of each individual and calculated the inbreeding coefficient value accordingly, whose mean value was 0.09.

CONCLUSION

Due to the limitation of population size and other factors, the genetic diversity of this Rongchang pig population is low. The results of this study can provide basic data to support the development of Rongchang pig breeding program, the establishment of SPF Rongchang pig closed herd and its experimental utilization.

Transcriptomic and Metabolomic Analyses Reveal the Key Genes Related to Shade Tolerance in Soybean

Soybean (Glycine max) is an important crop, rich in proteins, vegetable oils and several other phytochemicals, which is often affected by light during growth. However, the specific regulatory mechanisms of leaf development under shade conditions have yet to be understood. In this study, the transcriptome and metabolome sequencing of leaves from the shade-tolerant soybean 'Nanxiadou 25' under natural light (ND1) and 50% shade rate (SHND1) were carried out, respectively. A total of 265 differentially expressed genes (DEGs) were identified, including 144 down-regulated and 121 up-regulated genes. Meanwhile, KEGG enrichment analysis of DEGs was performed and 22 DEGs were significantly enriched in the top five pathways, including histidine metabolism, riboflavin metabolism, vitamin B6 metabolism, glycerolipid metabolism and cutin, suberine and wax biosynthesis. Among all the enrichment pathways, the most DEGs were enriched in plant hormone signaling pathways with 19 DEGs being enriched. Transcription factors were screened out and 34 differentially expressed TFs (DETFs) were identified. Weighted gene co-expression network analysis (WGCNA) was performed and identified 10 core hub genes. Combined analysis of transcriptome and metabolome screened out 36 DEGs, and 12 potential candidate genes were screened out and validated by quantitative real-time polymerase chain reaction (qRT-PCR) assay, which may be related to the mechanism of shade tolerance in soybean, such as ATP phosphoribosyl transferase (ATP-PRT2), phosphocholine phosphatase (PEPC), AUXIN-RESPONSIVE PROTEIN (IAA17), PURPLE ACID PHOSPHATASE (PAP), etc. Our results provide new knowledge for the identification and function of candidate genes regulating soybean shade tolerance and provide valuable resources for the genetic dissection of soybean shade tolerance molecular breeding.

Insight into the Interaction of Malondialdehyde with Rabbit Meat Myofibrillar Protein: Fluorescence Quenching and Protein Oxidation

This research explored the effects of oxidative modification caused by different malondialdehyde (MDA) concentrations on rabbit meat myofibrillar protein (MP) structural characteristics and the interactions between MDA and MP. The fluorescence intensity of MDA-MP adducts, and surface hydrophobicity increased, whereas the intrinsic fluorescence intensity and free-amine content of MPs decreased as MDA concentration and incubation time increased. The carbonyl content was 2.06 nmol/mg for native MPs, while the carbonyl contents increased to 5.17, 5.57, 7.01, 11.37, 13.78, and 23.24 nmol/mg for MP treated with 0.25 to 8 mM MDA, respectively. When the MP was treated with 0.25 mM MDA, the sulfhydryl content and the α-helix content decreased to 43.78 nmol/mg and 38.46%, while when MDA concentration increased to 8 mM, the contents for sulfhydryl and α-helix decreased to 25.70 nmol/mg and 15.32%. Furthermore, the denaturation temperature and ΔH decreased with the increase in MDA concentration, and the peaks disappeared when the MDA concentration reached 8 mM. Those results indicate MDA modification resulted in structural destruction, thermal stability reduction, and protein aggregation. Besides, the first-order kinetics and Stern-Volmer equation fitting results imply that the quenching mechanism of MP by MDA may be mainly driven by dynamic quenching.

Complete mitochondrial genome of Thuja sutchuenensis and its implications on evolutionary analysis of complex mitogenome architecture in Cupressaceae

BACKGROUND

The complex physical structure and abundant repeat sequences make it difficult to assemble the mitogenomes of seed plants, especially gymnosperms. Only approximately 33 mitogenomes of gymnosperms have been reported. However, as the most widely distributed and the second largest family among gymnosperms, Cupressaceae has only six assembled mitogenomes, including five draft mitogenomes and one complete mitogenome, which has greatly hindered the understanding of mitogenome evolution within this large family, even gymnosperms.

RESULTS

In this study, we assembled and validated the complete mitogenome of Thuja sutchuenensis, with a size of 2.4 Mb. Multiple sequence units constituted its complex structure, which can be reduced to three linear contigs and one small circular contig. The analysis of repeat sequences indicated that the numbers of simple sequence repeats increased during the evolutionary history of gymnosperms, and the mitogenome of Thuja sutchuenensis harboured abundant extra-long repeats (more than 5 kb). Additionally, the longest repeat sequence identified in these seven gymnosperms also came from the mitogenome of Thuja sutchuenensis, with a length of up to 47 kb. The analysis of colinear blocks and gene clusters both revealed that the orders of mitochondrial genes within gymnosperms was not conserved. The comparative analysis showed that only four tRNAs were shared by seven gymnosperms, namely, trnD-GUC, trnE-UUC, trnI-CAU and trnY-GUA. Furthermore, four genes have undergone potential positive selection in most gymnosperm species, namely, atp8, ccmB, mttB and sdh4.

CONCLUSION

We successfully assembled the second complete mitogenome within Cupressaceae and verified that it consisted of multiple sequence units. Our study also indicated that abundant long repeats may contribute to the generation of the complex conformation of the mitogenome of Thuja sutchuenensis. The investigation of Thuja sutchuenensis's mitogenome in our study provides new insight into further understanding the complex mitogenome architecture within gymnosperms.