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Roses are important plants, and they are cultivated worldwide for their beautiful flowers, remarkable scent, and nutritious hips. In this study, we re-sequenced the whole genomes of 57 rose cultivars and one wild species that originated from different regions around the world and had different scents, aiming to evaluate their genetic structure and to detect the potential signature of the selective sweep between different scent groups with single-nucleotide polymorphism (SNP) and indel markers. The roses were sequenced at an average depth of 6× to the reference genome of Rosa 'Old blush'. A total of 2,375,949 SNPs were obtained. The SNP numbers varied among the 58 samples, with an average of 1,271,906 per sample. The phylogeny and population structure revealed that the roses could be divided into three main clusters; however, the groups were not consistent in terms of geographic origin or scent classification. These indicated that rose cultivars have a complex genetic background due to the extensive hybridization between cultivated roses or wild rosa species worldwide. A selective sweep analysis was conducted to detect the selection signatures in rose scent traits. A total of 2430 candidate genes were identified in the strong scent groups, and were at the top 5% FST compared to the moderate group. These genes were significantly enriched in the KEGG pathways of tyrosine metabolism, cyanoamino acid metabolism, alpha-linolenic acid metabolism (13 genes), and phenylpropanoid biosynthesis (30 genes). When the low-scent group was used as the control, 2604 candidate genes were identified at the top 5% FST that were significantly enriched in the KEGG pathways of alpha-linolenic acid metabolism (15 genes), and glutathione metabolism (23 genes). We also observed genes enriched in pathways including the linoleic acid metabolism (five genes), diterpenoid biosynthesis (six genes), and monoterpenoid biosynthesis (seven genes), although they were not significant. These implied a positive selection of rose cultivars with a strong fragrance in terms of fatty acid derivatives, terpenoids and benzenoids/phenylpropanoids during rose breeding. Our study establishes a foundation for the further large-scale characterization of rose germplasm, improving the genetic knowledge of the background of roses. [ABSTRACT FROM AUTHOR]

Lactiplantibacillus plantarum has a strong carbohydrate utilization ability. This characteristic plays an important role in its gastrointestinal tract colonization and probiotic effects. L. plantarum LP-F1 presents a high carbohydrate utilization capacity. The genome analysis of 165 L. plantarum strains indicated the species has a plenty of carbohydrate metabolism genes, presenting a strain specificity. Furthermore, two-component systems (TCSs) analysis revealed that the species has more TCSs than other lactic acid bacteria, and the distribution of TCS also shows the strain specificity. In order to clarify the sugar metabolism mechanism under different carbohydrate fermentation conditions, the expressions of 27 carbohydrate metabolism genes, catabolite control protein A (CcpA) gene ccpA, and TCSs genes were analyzed by quantitative real-time PCR technology. The correlation analysis between the expressions of regulatory genes and sugar metabolism genes showed that some regulatory genes were correlated with most of the sugar metabolism genes, suggesting that some TCSs might be involved in the regulation of sugar metabolism. [ABSTRACT FROM AUTHOR]

Gamma-aminobutyric acid (GABA) is widely distributed in nature and considered a potent bioactive compound with numerous and important physiological functions, such as anti-hypertensive and antidepressant activities. There is an ever-growing demand for GABA production in recent years. Lactic acid bacteria (LAB) are one of the most important GABA producers because of their food-grade nature and potential of producing GABA-rich functional foods directly. In this paper, the GABA-producing LAB species, the biosynthesis pathway of GABA by LAB, and the research progress of glutamate decarboxylase (GAD), the key enzyme of GABA biosynthesis, were reviewed. Furthermore, GABA production enhancement strategies are reviewed, from optimization of culture conditions and genetic engineering to physiology-oriented engineering approaches and co-culture methods. The advances in both the molecular mechanisms of GABA biosynthesis and the technologies of synthetic biology and genetic engineering will promote GABA production of LAB to meet people's demand for GABA. The aim of the review is to provide an insight of microbial engineering for improved production of GABA by LAB in the future. [ABSTRACT FROM AUTHOR]

Fertility preservation for male childhood cancer survivors not yet capable of producing mature spermatozoa, relies on experimental approaches such as testicular explant culture. Although the first steps in somatic maturation can be observed in human testicular explant cultures, germ cell depletion is a common obstacle. Hence, understanding the spermatogonial stem cell (SSC) niche environment and in particular, specific components such as the seminiferous basement membrane (BM) will allow progression of testicular explant cultures. Here, we revealed that the seminiferous BM is established from 6 weeks post conception with the expression of laminin alpha 1 (LAMA 1) and type IV collagen, which persist as key components throughout development. With prepubertal testicular explant culture we found that seminiferous LAMA 1 expression is disrupted and depleted with culture time correlating with germ cell loss. These findings highlight the importance of LAMA 1 for the human SSC niche and its sensitivity to culture conditions.

Streptococcus thermophilus is one of the most valuable homo-fermentative lactic acid bacteria, which, for a long time, has been widely used as a starter for the production of fermented dairy products. The key production characteristics of S. thermophilus , for example the production of extracellular polysaccharide, proteolytic enzymes and flavor substances as well as acidifying capacity etc., have an important effect on the quality of dairy products. The acidification capacity of the strains determines the manufacturing time and quality of dairy products. It depends on the sugar utilization ability of strains. The production of extracellular polysaccharide is beneficial for improving the texture of dairy products. Flavor substances increase the acceptability of dairy products. The proteolytic activity of the strain influences not only the absorption of the nitrogen source, but also the formation of flavor substances. Different strains have obvious differences in production characteristics via long-time evolution and adaptation to environment. Gaining new strains with novel and desirable characteristics is an important long-term goal for researchers and the fermenting industry. The understanding of the potential molecular mechanisms behind important characteristics of different strains will promote the screening and breeding of excellent strains. In this paper, key technological and functional properties of different S. thermophilus strains are discussed, including sugar metabolism, proteolytic system and amino acid metabolism, and polysaccharide and flavor substance biosynthesis. At the same time, diversity of genomes and plasmids of S. thermophilus are presented. Advances in research on key production characteristics and molecular levels of S. thermophilus will increase understanding of molecular mechanisms of different strains with different important characteristics, and improve the industrialization control level for fermented foods., Competing Interests: The authors declare no conflict of interest.

Plasmids are widely distributed in different sources of lactic acid bacteria (LAB) as self-replicating extrachromosomal genetic materials, and have received considerable attention due to their close relationship with many important functions as well as some industrially relevant characteristics of the LAB species. They are interesting with regard to the development of food-grade cloning vectors. This review summarizes new developments in the area of lactic acid bacteria plasmids and aims to provide up to date information that can be used in related future research.

Class IIa bacteriocins are heat-stable, unmodified peptides with a conserved amino acids sequence YGNGV on their N-terminal domains, and have received much attention due to their generally recognized as safe (GRAS) status, their high biological activity, and their excellent heat stability. They are promising and attractive agents that could function as biopreservatives in the food industry. This review summarizes the new developments in the area of class IIa bacteriocins and aims to provide uptodate information that can be used in designing future research.