Quantitative trait loci mapping reveals the complexity of adult plant resistance to leaf rust in spring wheat ‘Copio’

The spring wheat (Triticum aestivum L.) line ‘Copio’ has exhibited high level of adult plant resistance (APR) to the leaf rust (Puccinia triticina) pathogen in Mexico during field evaluations. To elucidate the genetic basis of leaf rust resistance in Copio, 176 F4-derived F6-recombinant inbred lines (RILs) from a cross of wheat lines ‘Apav’ and Copio were phenotyped in the field for two seasons in the United States and Mexico. A total of 762 genotyping-by-sequencing (GBS) single nucleotide polymorphic (SNP) markers were used to develop linkage maps. Composite interval mapping identified seven quantitative trait loci (QTL), all contributed by Copio. Three QTL on chromosome arms 1BL (QLr.umn-1B), 2AS (QLr.umn-2A), and 3BS (QLr.umn-3B) were consistently expressed across all four environments. The QTL on 1BL represents Lr46, which is a pleiotropic APR gene, while the QTL on 2AS is colocated to the Lr37 gene in the 2NS/2AS translocation fragment. The QTL on 3BS, mapped to the Sr2/Yr30/Lr27 genomic region, is more likely to be a unique locus conferring APR to leaf rust races because all phenotyping environments had Lr27 virulent pathotypes. Moreover, the functionality of Lr27 is complimented by Lr31 on chromosome 4BS, which is lacking in both parents. Marker haplotypes identified seven RILs carrying a combination of resistance alleles at all three loci. This combination reduced leaf rust coefficient of infection up to 52 and 36% in the Mexican and U.S. environments, respectively. This study reports the complex genetic mechanism of APR to leaf rust in Copio and its importance as a potential resistance source for gene pyramiding through recombination breeding

miR-205-5p Mediated Downregulation of PTEN Contributes to Cisplatin Resistance in C13K Human Ovarian Cancer Cells

Cisplatin resistance is a major cause of treatment failure in advanced ovarian cancer. The limited evidence shows the paradoxical regulation of miR-205 on chemotherapy resistance in cancer. Herein, we found that miR-205-5p was enormously increased in cisplatin-resistant C13K ovarian cancer cells compared with its cisplatin-sensitive OV2008 parental cells using miRNA microarrays, which was further verified by quantitative PCR. Furthermore, we confirmed that inhibition of miR-205-5p upregulated PTEN and subsequently attenuated its downstream target p-AKT, which inversed C13K cells from cisplatin resistance to sensitivity. Our data suggest that miR-205-5p contributes to cisplatin resistance in C13K ovarian cancer cells may via targeting PTEN/AKT pathway

Identification and characterization of resistance loci to wheat leaf rust and stripe rust in Afghan landrace “KU3067”

Leaf rust and stripe rust are important wheat diseases worldwide causing significant losses where susceptible varieties are grown. Resistant cultivars offer long-term control and reduce the use of hazardous chemicals, which can be detrimental to both human health and the environment. Land races have been a valuable resource for mining new genes for various abiotic and biotic stresses including wheat rusts. Afghan wheat landrace “KU3067” displayed high seedling infection type (IT) for leaf rust and low IT for stripe rust; however, it displayed high levels of field resistance for both rusts when tested for multiple seasons against the Mexican rust isolates. This study focused on identifying loci-conferring seedling resistance to stripe rust, and also loci-conferring adult plant resistance (APR) against the Mexican races of leaf rust and stripe rust. A backcrossed inbred line (BIL) population advanced to the BC1F5 generation derived from the cross of KU3067 and Apav (triple rust susceptible line) was used for both, inheritance and QTL mapping studies. The population and parents were genotyped with Diversity Arrays Technology-genotyping-by-sequencing (DArT-Seq) and phenotyped for leaf rust and stripe rust response at both seedling and adult plant stages during multiple seasons in Mexico with relevant pathotypes. Mapping results identified an all-stage resistance gene for stripe rust, temporarily designated as YrKU, on chromosome 7BL. In total, six QTL-conferring APR to leaf rust on 1AS, 2AL, 4DL, 6BL, 7AL, and 7BL, and four QTL for stripe rust resistance on 1BS, 2AL, 4DL, and 7BL were detected in the analyses. Among these, pleiotropic gene Lr67/Yr46 on 4DL with a significantly large effect is the first report in an Afghan landrace-conferring resistance to both leaf and stripe rusts. QLr.cim-7BL/YrKU showed pleiotropic resistance to both rusts and explained 7.5–17.2 and 12.6–19.3% of the phenotypic variance for leaf and stripe rusts, respectively. QYr.cim-1BS and QYr.cim-2AL detected in all stripe environments with phenotypic variance explained (PVE) 12.9–20.5 and 5.4–12.5%, and QLr.cim-6BL are likely to be new. These QTL and their closely linked markers will be useful for fine mapping and marker-assisted selection (MAS) in breeding for durable resistance to multiple rust diseases

Genomic Characterization and High Prevalence of Bocaviruses in Swine

Using random PCR amplification followed by plasmid subcloning and DNA sequencing, we detected bocavirus related sequences in 9 out of 17 porcine stool samples. Using primer walking, we sequenced the nearly complete genomes of two highly divergent bocaviruses we provisionally named porcine bocavirus 1 isolate H18 (PBoV1-H18) and porcine bocavirus 2 isolate A6 (PBoV2-A6) which differed by 51.8% in their NS1 protein. Phylogenetic analysis indicated that PBoV1-H18 was very closely related to a ∼2 Kb central region of a porcine bocavirus-like virus (PBo-LikeV) from Sweden described in 2009. PBoV2-A6 was very closely related to the porcine bocavirus genomes PBoV-1 and PBoV2 from China described in 2010. Among 340 fecal samples collected from different age, asymptomatic swine in five Chinese provinces, the prevalence of PBoV1-H18 and PBoV2-A6 related viruses were 45–75% and 55–70% respectively, with 30–47% of pigs co-infected. PBoV1-A6 related strains were highly conserved, while PBoV2-H18 related strains were more diverse, grouping into two genotypes corresponding to the previously described PBoV1 and PBoV2. Together with the recently described partial bocavirus genomes labeled V6 and V7, a total of three major porcine bocavirus clades have therefore been described to date. Further studies will be required to elucidate the possible pathogenic impact of these diverse bocaviruses either alone or in combination with other porcine viruses

A Multi-functional st-ELR Scaffold for Dentin Regeneration

University of Minnesota Ph.D. dissertation. 2018. Major: Oral Biology. Advisor: Conrado Aparicio. 1 computer file (PDF); 163 pages.Pulpitis is one of the most widespread diseases in the world. Current advances in dental tissue engineering have provided an interesting alternative therapeutic approach in the field of regenerative endodontics. However, there remains a strong need to develop an optimized scaffold for supporting dentin regeneration. The objective of this PhD project is to develop a dental scaffold using elastin-like recombinamers(ELRs) to stimulate dentin regeneration while exhibiting antimicrobial ability to control potential re-infection of the pulp cavity. To provide a biomimetic scaffold that resembles the extracellular matrix in dentin tissue, we fabricated fibrous scaffold of ELRs using electrospinning technique and analyzed its ability in inducing biomimetic mineralization using the polymer-induced liquid precursor (PILP) process. The ELR scaffolds exhibited intra- and extra-fibrous mineralization, which highly mimicked the structure of mineralized native collagen in dentin. The scaffold is expected to be applied in the pulp cavity with direct contact with the pulp tissue. Therefore, we investigated the interaction between the mineralized ELR scaffold that contains statherin-derived peptide (st-ELR) and human dental pulp stem cells (hDPSCs). Proliferation and odontogenic differentiation of hDPSCs were analyzed and the study indicated that biomimetically mineralized st-ELR scaffold supported the proliferation and odontogenic differentiation of hDPSCs. Bacterial infection is considered as the major reason for the failure of implanted materials. Therefore, we functionalized st-ELR scaffold with antimicrobial peptides to prevent the potential infection caused by oral bacteria. A cysteine modified antimicrobial peptide GL13K(Cys-GL13K) was used in this study to achieve site-specific modification on the developed scaffold. First, we tethered Cys-GL13K peptides on titanium surface to analyze the properties and antimicrobial ability of immobilized peptides. A homogenous and strong coating of peptides was obtained. The tethered peptides exhibited promising antimicrobial ability against S. mutans, S. gordonii and E. faecalis. Furthermore, we bio-conjugated the peptides to st-ELR membranes using the same modification technique. Successful peptide modification was achieved, and the peptide functionalized st-ELR membrane exerted antimicrobial ability against S. mutans and S. gordonii. This research sheds light on the development and functionalization of scaffolds for the application of regenerating hard tissues such as dentin and bone. It allows the scaffold to highly resemble the architecture and physical properties of extracellular matrix in mineralized tissues. In addition, this research provides a new approach to modify the scaffold with diverse bioactive molecules to obtain multiple functions, while maintaining good interaction with native tissues