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Background The livestock industry is striving to identify antibiotic alternatives to reduce the need to use antibiotics. Postbiotics, such as Saccharomyces cerevisiae fermentation product (SCFP), have been studied and proposed as potential non-antibiotic growth promoters due to their effects on animal growth and the rumen microbiome; however, little is known of their effects on the hind-gut microbiome during the early life of calves. The objective of this study was to measure the effect of in-feed SCFP on the fecal microbiome of Holstein bull calves through 4 months of age. Calves (n = 60) were separated into two treatments: CON (no SCFP added) or SCFP (SmartCare®, Diamond V, Cedar Rapids, IA, in milk replacer and NutriTek®, Diamond V, Cedar Rapids, IA, incorporated into feed), and were blocked by body weight and serum total protein. Fecal samples were collected on d 0, 28, 56, 84, and 112 of the study to characterize the fecal microbiome community. Data were analyzed as a completely randomized block design with repeated measures when applicable. A random-forest regression method was implemented to more fully understand community succession in the calf fecal microbiome of the two treatment groups. Results Richness and evenness of the fecal microbiota increased over time (P P = 0.06). Based on random-forest regression, calf age as predicted by microbiome composition was significantly correlated with the calf physiological age (R2 = 0.927, P −15). Twenty-two “age-discriminatory” ASVs (amplicon sequence variants) were identified in the fecal microbiome that were shared between the two treatment groups. Of these, 6 ASVs (Dorea-ASV308, Lachnospiraceae-ASV288, Oscillospira-ASV311, Roseburia-ASV228, Ruminococcaceae-ASV89 and Ruminoccocaceae-ASV13) in the SCFP group reached their highest abundance in the third month, but they reached their highest abundance in the fourth month in the CON group. All other shared ASVs reached their highest abundance at the same timepoint in both treatment groups. Conclusions Supplementation of SCFP altered the abundance dynamics of age discriminatory ASVs, suggesting a faster maturation of some members of the fecal microbiota in SCFP calves compared to CON calves. These results demonstrate the value of analyzing microbial community succession as a continuous variable to identify the effects of a dietary treatment.

Phenylpropanoid pathway related genes were identified and analyzed by co-expression network and expression pattern. NST1 may regulate the expression of CAD to affect the lignin deposition of ‘Liehe’ apricot endocarp. Apricot (Prunus Armeniaca L.) is a typical Rosaceae stone fruit tree. The extensive lignification of its endocarp is an important metabolic event during fruit ripening. There are abundant apricot germplasm resources in China, including a special apricot cultivar, ‘Liehe’ (LE), which has a thin, soft, cleavable endocarp with a hardness 45.84% that of the ‘Jinxihong’ (JG) apricot (with normal hardened-endocarp). To understand the molecular mechanisms behind the LE phenotype, differentially expressed genes (DEGs) encoding key enzymes involved in phenylpropanoid biosynthesis were mined from transcriptome data by the co-expression network and expression patterns. DEGs encoding key enzymes involved in phenylpropanoid biosynthesis were significantly down-regulated in LE, and the activity of these enzymes exhibited similar results. NST1 (NAC secondary wall thickening promoting factor 1) expression levels in LE were only 13.7%, 2.8%, 9.4%, and 82.5% that in JG at 9, 15, 21, and 30 days after full bloom (DAFB), respectively. CAD (Cinnamyl alcohol dehydrogenase) expression levels in LE were 1.3%, 0.7%, 0.2% and 2.7% that in JG at 15, 21, 30, 49 DAFB, respectively. CAD activity in LE was 46.4% and 63.6% that in JG at 42 and 49 DAFB, respectively. We thus used homologous cloning to determine the sequence differences of CAD and NST1 in LE and JG. Our results will help understand the molecular mechanisms underlying endocarp cleavage in LE apricot and provide a useful reference for further investigation of lignification during endocarp development. NST1 may regulate CAD which involved in the phenylpropanoid pathway and affect lignin deposition in LE endocarp.

In the subgenus Prunophora of the genus Prunus, many transitional traits presented in interspecific hybrids, the so-called ‘new species’, were frequently named due to the complicated botanical classification system. In this study, we used 16 nuclear simple sequence repeats (nSSRs) and 10 chloroplast simple sequence repeats (cpSSRs) to evaluate genetic relationships among 42 accessions, which included 15 putative interspecific hybrids, and then to reveal the speciation and differentiation in the subgenus Prunophora. In total, 231 and 27 alleles were observed in nSSRs and cpSSRs respectively; and with cpSSRs 20 haplotypes were revealed among the accessions. Furthermore, the haplotype and genetic structure analysis implied that (1) Prunus simonii Carr. might be a subspecies or a forma of Prunus salicina L., rather than an interspecific hybrid between P. salicina and Prunus armeniaca L., (2) Prunus limeixing Zhang et Wang was derived from a natural hybrid with P. salicina as its maternal progenitor and P. armeniaca as the female parent, and (3) Prunus cathayana Fu et al. (or kernel-using apricot) was an interspecific hybridization species of P. armeniaca (maternal parent) and Prunus sibirica L. (female parent). These results will be useful for clarifying the problems in the botanical classification, and facilitate the conservation and management of plum and apricot genetic resources in the Chinese National Germplasm Repository for Plums and Apricots.