Genetic diversity analysis and fingerprint construction of Korean pine (Pinus koraiensis) clonal seed orchard.

Korean pine is a native tree species in Northeast China. In order to meet the needs of germplasm resource evaluation and molecular marker-assisted breeding of Korean pine, we collected Korean pine clones from 7 populations in Northeast China, analyzed the genetic diversity and genetic structure by SSR molecular marker technology and clustered them to revealed the inter- and intrapopulation differentiation characteristics of each clone. The fingerprint profiles of 161 Korean pine clones were also constructed. 77 alleles were detected for 11 markers, and 18 genotypes were identified on average for each marker. The PIC of the different markers ranged from 0.155-0.855, and the combination of PI and PIsibs for the 11 markers was 3.1 × 10-8 and 1.14 × 10-3, respectively. MANOVA showed that genetic variation existed mainly within populations, accounting for 98% of the total variation. The level of genetic differentiation among populations was low, with an average Nm between populations of 11.036. Genetic diversity is lower in the Lushuihe population and higher in the Tieli population. The 161 Korean pine clones were divided into 4 or 7 populations, and the 7 populations were not clearly distinguished from each other, with only the Lushuihe population showing partial differentiation. There is no significant correlation between the genetic distance of Korean pine populations and the geographical distance of their superior tree sources. This result can provide recommendations for future Korean pine breeding programs. The combination of 11 markers could completely distinguish 161 clones and establish the fingerprint. Genetic diversity of Korean pine clones from the 7 populations was abundant, and the genetic distances of individuals and populations were evenly dispersed. The fingerprint map can be used for the identification of Korean pine clones.

Glutathione, carbohydrate and other metabolites of Larix olgensis A. Henry reponse to polyethylene glycol-simulated drought stress.

Drought stress in trees limits their growth, survival, and productivity and it negatively affects the afforestation survival rate. Our study focused on the molecular responses to drought stress in a coniferous species Larix olgensis A. Henry. Drought stress was simulated in one-year-old seedlings using 25% polyethylene glycol 6000. The drought stress response in these seedlings was assessed by analyzing select biochemical parameters, along with gene expression and metabolite profiles. The soluble protein content, peroxidase activity, and malondialdehyde content of L. olgensis were significantly changed during drought stress. Quantitative gene expression analysis identified a total of 8172 differentially expressed genes in seedlings processed after 24 h, 48 h, and 96 h of drought stress treatment. Compared with the gene expression profile of the untreated control, the number of up-regulated genes was higher than that of down-regulated genes, indicating that L. olgensis mainly responded to drought stress through positive regulation. Metabolite analysis of the control and stress-treated samples showed that under drought stress, the increased abundance of linoleic acid was the highest among up-regulated metabolites, which also included some saccharides. A combined analysis of the transcriptome and metabolome revealed that genes dominating the differential expression profile were involved in glutathione metabolism, galactose metabolism, and starch and sucrose metabolism. Moreover, the relative abundance of specific metabolites of these pathways was also altered. Thus, our results indicated that L. olgensis prevented free radical-induced damage through glutathione metabolism and responded to drought through sugar accumulation.

Defining the mechanism of PDI interaction with disulfide-free amyloidogenic proteins: Implications for exogenous protein expression and neurodegenerative disease.

Protein disulfide isomerase (PDI) is an important molecular chaperone capable of facilitating protein folding in addition to catalyzing the formation of a disulfide bond. To better understand the distinct substrate-screening principles of Pichia pastoris PDI (Protein disulfide isomerase) and the protective role of PDI in amyloidogenic diseases, we investigated the expression abundance and intracellular retention levels of three archetypal amyloidogenic disulfide bond-free proteins (Aß42, α-synuclein (α-Syn) and SAA1) in P. pastoris GS115 strain without and with the overexpression of PpPDI (P. pastoris PDI). Intriguingly, amyloidogenic Aß42 and α-Syn were detected only as intracellular proteins whereas amyloidogenic SAA1 was detected both as intracellular and extracellular proteins when these proteins were expressed in the PpPDI-overexpressing GS115 strain. The binding between PpPDI and each of the three amyloidogenic proteins was investigated by molecular docking and simulations. Three different patterns of PpPDI-substrate complexes were observed, suggesting that multiple modes of binding might exist for the binding between PpPDI and its amyloidogenic protein substrates, and this could represent different specificities and affinities of PpPDI toward its substrates. Further analysis of the proteomics data and functional annotations indicated that PpPDI could eliminate the need for misfolded proteins to be partitioned in ER-associated compartments.