Improving Rice Blast Resistance by Mining Broad-Spectrum Resistance Genes at Pik Locus

Magnaporthe oryzae is known for its genetic diversity and pathogenic variability,leading to rapid breakdown of resistance in rice.Incorporating multiple broad-spectrum blast resistance genes into rice cultivars would extend disease resistance longevity.Effective resistance breeding in rice therefore requires continual enrichment of the reservoir of resistance genes and alleles.We conducted a large-scale screen of rice blast resistance in about 2000 rice accessions.Among them,247 accessions showed at least medium resistance to the natural infection of rice blast and 7 novel Pik alleles were identified from them.Variations in gene sequences were then correlated with the phenotypic trait to enable the identification of favorable alleles.Among the seven novel Pik alleles,the resistant rate of Pik-R0/ME/7017 donors was greater than 80%,and the disease score was less than 3.Through molecular marker-assisted backcross breeding,we successfully transferred the three Pik alleles,Pik-R0/ME/7017,into an elite cultivated line Kongyu 131 to obtain BC_(3)F_(2)lines,which showed enhanced resistance to rice blast compared with the recurrent parent.Assessment of these near-isogenic lines in the greenhouse using 31 isolates of M.oryzae from Heilongjiang Province of China revealed that the resistant levels of the BC_(3)F_(2)lines with Pik-R0/ME/7017 were significantly higher than those of the established cloned resistance genes Pik-m and Pi1.Exploring such alleles will enrich our gene library for resistance to rice blast.

Cloning and Analysis of NBS-LRR Type Resistance Gene Analogues in Sweet Potato (Ipomoea batatas)

The degenerate primers were designed based on the conserved NBS-LRR motifs among the known disease-resistance genes. A fragment of about 500 bp was amplified from genomic DNA of sweet potato using the specifically designed degenerate primers. After cloning and sequencing, 20 NBS-LRR type of disease-resistance gene analogue （RGAs） in sweet potato were observed. The deduced amino acid sequence of DNA fragment contains the conserved motifs of NBS-LRR type RGAs, such as P-loop, Kinase-2α, Kinase-3α and GLPL domain. The 20 RGAs could be sorted into two subclasses, namely TIR- NBS-LRR type and non-TIR-NBS-LRR type. Compared with the known resistance genes including N, L6 and M, the percentages of homologous amino acid sequence in 10 TIR-NBS-LRR range between 21% -44%. While other 10 non-TIR-NBS-LRR assume 15% -46% homology with the known resistance genes （Prf, RPM1, RPS2, etc. ）. Consequently the RGAs may further be used as molecular marker for screening the candidate disease-resistance genes in sweet potato.

Variations of Melanocortin Receptor 1 (MC1R) Gene in Three Pig Breeds

Variations of Melanocortin Receptor 1 （MC1R） were investigated using sequencing, PCR-RFLP and PCR-SSCP, in three pig breeds, Landrace, Yorkshire, and Duroc. Five polymorphic sites were found, in which 668G→C occurred within 5＇ UTR, nt894insCC in coding region resulting in a premature stop at codon 56, and 1318C→T, 1554G→A, l197G→A in coding region resulting in Ala164Val, Ala243Thr, and Asp124Asn respectively. All individuals in Landrace and Yorkshire present homozygous 668GG, 1197AA, 1318CC, and 1554GG, and have CC insertions at the 894 site, whereas the individuals in Duroc present a contrast homozygous 668CC, 1197GG, 1318TT, and 1554AA, and have no CC insertions at the corresponding site. No heterozygote has been found at these mutation sites. Presumably, 668G→C, 1318C→T, and 1554G→A may be associated with the recessive red color in the Duroc breed, and nt894insCC making 1197G→A nonsense may be associated with the white color in Landrace and Yorkshire breeds.

Current understanding of maize and rice defense against insect herbivores

Plants have sophisticated defense systems to fend off insect herbivores. How plants defend against herbivores in dicotyledonous plants, such as Arabidopsis and tobacco, have been relatively well studied, yet little is known about the defense responses in monocotyledons. Here, we review the current un- derstanding of rice （Oryza sativa） and maize （Zea rnays） defense against insects. In rice and maize, elicitors derived from insect herbivore oral secretions or oviposition fluids activate phytohormone signaling, and transcriptomic changes mediated mainly by transcription factors lead to accumulation of defense-related secondary metabolites. Direct defenses, such as trypsin protein inhibitors in rice and benzoxazinoids in maize, have anti-digestive or toxic effects on insect herbivores. Herbivory-induced plant volatiles, such as terpenes, are indirect defenses, which attract the natural enemies of herbivores. R gene-mediated defenses against herbivores are also discussed.

Melanocortin-1 receptor gene variants in four Chinese ethnic populations

There is strong relationship between melanocortin-1 receptor (MCIR) gene variants and human hair color and skin type. Based on a sequencing study of MC1R gene in 50 individuals from the Uygur, Tibetan, Wa and Dai ethnic populations, we discuss the occurrence of 7 mc1r variants consisting of 5 nonsynonymous sites (Val60Leu, Arg67Gln, Val92Met, Arg163Gln and Ala299Val) and 2 synonymous sites (C414T and A942G), among which C414T and Ala299Val were reported for the first time. Confirmation and analysis were the made of 122 individuals at three common point mutations (Val92Met, Arg163Gln, A942G) using PCR-SSCP. The frequency of Arg163Gln variant varies in the four ethnic populations, with percentage of 40%, 85.0%, 66. 2% and 72.7%, respectively, while those of Val92Met and A942G are roughly similar in these four populations. The different environments, migration and admixture of various ethnic groups in China might have impact on the observed frequency of Arg163Gln.

Recent advances and emerging trends in antiviral defense networking in rice

Plants and viruses coexist in the natural ecosystem for extended periods of time,interacting with each other and even coevolving,maintaining a dynamic balance between plant disease resistance and virus pathogenicity.During virus–host interactions,plants often exhibit abnormal growth and development.However,plants do not passively withstand virus attacks but have evolved sophisticated and effective defense mechanisms to resist,limit,or undermine virus infections.It is widely believed that the initial stage of infection features the most intense interactions between the virus and the host and the greatest variety of activated signal transduction pathways.This review describes the most recent findings in rice antiviral research and discusses a variety of rice antiviral molecular mechanisms,including those based on R genes and recessive resistance,RNA silencing,phytohormone signaling,autophagy and WUSmediated antiviral immunity.Finally,we discuss the challenges and future prospects of breeding rice for enhanced virus resistance.

Cloning and Characterization of Full Length cDNA of a CC-NBS-LRR Resistance Gene in Sweetpotato

Conserved domain such as nucleotide binding site （NBS） was found in several cloned plant disease resistance genes. Based on the NBS domain, resistance gene analogues （RGAs） have been isolated. A full-length cDNA, SPR1 was obtained by rapid amplification of cDNA ends （RACE） method. Sequence analysis indicated that the length of SPR1 was 3 066 bp, including a complete open reading frame of 2 667 bp encoding SPR1 protein of 888 amino acids. Compared with known NBS-LRR genes, it presented relatively high amino acid sequence identity. The polypeptide has a typical structure of nonT1R-NBS-LRR genes, with NB-ARC, CC, and LRR domains. The SPR1-related sequences belonged to multicopy gene family in sweetpotato genome according to the result of Southern blotting. Semi-quantitative RT-PCR analysis showed SPR1 expressed in all tested tissues. The cloning of putative resistance gene from sweetpotato provides a basis for studying the structure and function of sweetpotato disease-resistance relating genes and disease resistant genetic breeding in sweetpotato. The gene has been submitted to the GenBank database, and the accession number is EF428453.

Phylogenetic Diversity of Microorganisms from Chemocline of the Meromictic Soda Lake Doroninskoe(Zabaikalie,Russia)

1 Introduction Many soda and salt lakes are characterized by the formation of the meromictic conditions under which a part of the water column is not involved in the annual process of mixing(Mac Intyre,Melack,1982).This creates an

Molecular identifi cation and population diff erentiation of Aurelia spp.ephyrae in sea cucumber aquaculture ponds of northern China

Aurelia spp.ephyrae have been reported to form blooms in sea cucumber aquaculture ponds in the Bohai and Yellow Seas.To identify the species,we carried out a genetic analysis of Aurelia spp.ephyrae and medusae based on mitochondrial 16 S rRNA gene.Samples offour Aurelia sp.ephyrae populations were collected in sea cucumber aquaculture ponds and samples offour Aurelia sp.medusae populations were collected in coastal waters.Using a BLASTn search,we found that both the ephyrae collected in the aquaculture ponds and medusae collected in coastal waters belong to Aurelia coerulea.Seventeen haplotypes were recovered from the 16 S rRNA gene.The overall haplotype diversity and nucleotide diversity of the 166 A.coerulea individuals were 0.686%and 0.329%,respectively,indicating high haplotype diversity and low nucleotide diversity.Moreover,the haplotype diversity of ephyrae populations were generally lower than that of medusae populations with close sampling points.The genetic differentiation between ephyrae populations collected in the sea cucumber aquaculture ponds and A.coerulea medusae collected in coastal waters was not significant,suggesting the ephyrae populations in the sea cucumber culture ponds were part of the same genetic group as the medusae populations in the coastal waters.Phylogeographic analysis of the 16 S rRNA region revealed that there was no significant correlation between the haplotypes and the geographic distribution of populations.Pairwise fixation index values showed significant genetic differentiation and limited gene flow between A.coerulea population of Weifang and other locations.

Polymorphism of Coding Sequences of IGF1R Gene in Baise Horses and Thoroughbred

[ Objective]The aim was to study polymorphism of mat-peptide sequence of IGF1 R gene in Baise horses and thoroughbred, which would af- ford reference for the further studies on the dwarf mechanism and molecular breeding in horses. [Method] A total of 57 blood samples of each breed were collected and genomic DNA was extracted by the standard phenol -chloroform method. Five DNA pools of each breed were constituted and polymorphism sites were identified by sequencing PCR products. Frequencies of genotypes and alleles at these sites of each breed were checked by PCR-RFLP. [Result] Four polymorphism sites were identified in exon 2, 5 and 16, including mutations of T406C, T179 627C, G212 077A and G2.12 110A. No difference was found in the frequency of T179 627C between the Baise horses and thoroughbred. The mutation （3212 077A was only found in the thorou- ghbred, and the mutations, T406C and G212 110A, were only checked out in the Baise horses. [ Conclusion] Whether these mutations are associated with horse growth needs further studies.

Complement Gene Mutation and Ehlers-Danlos Syndrome

Background: Dental complications of Ehlers-Danlos syndrome (EDS) include periodontitis with gum fragility and inflammation, enamel hypoplasia with frequent caries, high palate with dental crowding, TMJ instability, sutural dehiscence or scarring, and insensitivity to anesthetics. Objective: Determine if EDS dental complications always define a specific type and genetic cause or if they can arise as a general consequence of altered inflammatory response in EDS. Method: We compared findings of a 58-year-old female with complement component 1R (C1R) gene mutation (c.1553A > T, p.Asp518Val) found by whole exome sequencing to 43 patients with C1R gene mutations ascertained because of periodontal disease and to 710 EDS patients conventially ascertained because of joint and skin laxity. Result: Female patients ascertained as periodontal EDS showed the expected higher frequency of periodontitis (96% versus 14%) but had similar frequencies of hypermobility (81% versus 90%) and some skin findings (84% versus 92% with skin fragility) as the general group and our female patient who shared their C1R gene change. Her oromandibular bone loss rather than gum disease may reflect the more carboxy-terminal position of her C1R gene mutation compared to those in the patients identified as periodontal EDS. Conclusion: While mutation of the C1R gene may predict more frequent periodontal, skin, and vascular complications, focus on an articulo-autonomic dysplasia process that includes mast-cell activation and altered inflammatory response rather than extreme EDS types will help dentists and other subspecialists identify all EDS patients and anticipate their frequent oral manifestations.

Cloning and Expression Level Analysis of Melanocyte-stimulating Hormone Receptor 1 Gene(MC1R) in Alpacas with Different Coat Color

Specific primers for the MC1R gene of alpacas(GenBank EU1358800) were designed to amplify the cDNA sequence using RT-PCR to seek variation in the sequence and explore the relationship between the expression level of MC1R gene and alpaca coat color.The MC1R gene from white alpaca was cloned successfully and sequence analysis verified that the MC1R gene,encoding 317 amino acids,was 1081 bp in length.Compared with the existing sequence in GenBank,sequence identity was 99.9%and 7 mutations were found.Primers,designed from the sequence obtained,were used to assess the relative expression of MC1R in alpacas of different coat color using QRT-PCR and SPSS 13.0 software.Relative expression of MC1R in the skin of brown alpacas was 4.32 times higher than that in white alpacas after normalization with GAPDH(P【0.01),indicating that MC1R expression may be related to coat color of alpacas.

A Neurobiological Examination of Environmental, Subjective, Peripheral and Central Taste Sensation Processing Variances Associated with Taste Alterations: A Case Study Method

This study examines a common phenomenon that is greatly ignored by the clinical community for numerous reasons. Many people for a multitude of reasons experience taste alterations. The supertaster phenomenon is an alteration of taste that requires more investigation. In this study, a proband was examined for subjective reports of a taste alteration to determine its nature through a medical history examination and interview as well as any recollections of the taste disorder in her life. Through this examination, it was found that medical history examination and interview of the proband that many members of her nuclear family showed traits of the same taste disorder or in the case of one family member being a suspect for the taste alteration and one member not showing any signs because of genetic diversity as a half-sibling. Taste disorders are heritable, have multiple health and mental health consequences, influence life choices including mate choice, avoidance behaviors, social choices, alcohol use/abuse, smoking, food choices, and more. More awareness is needed in the research and clinical community into taste alterations as well as calls for future research from neuroscience, biomedical science, life science, and allied science community to investigate taste alterations.

Management of the Case of a Young Female Patient with Multiple Malignancies and Germline R24P CDKN2A Gene Mutation

The case of a young female patient with metachronous primary melanomas, advanced breast and pancreatic cancers is reported. The 5 different tumors diagnosed within six years, were managed with curative intent. Genetic analysis revealed the mutation of the R24P CDKN2A gene in a heterozygote form in both the patient and her father. Careful tertiary prevention during the follow-up of the patient is needed.

An atypical NLR gene confers bacterial wilt susceptibility in Arabidopsis

Quantitative disease resistance(QDR)remains the most prevalent form of plant resistance in crop fields and wild habitats.Genome-wide association studies(GWAS)have proved to be successful in deciphering the quantitative genetic basis of complex traits such as QDR.To unravel the genetics of QDR to the devastating worldwide bacterial pathogen Ralstonia solanacearum,we performed a GWAS by challenging a highly polymorphic local mapping population of Arabidopsis thaliana with four R.solanacearum type III effector(T3E)mutants,identified as key pathogenicity determinants after a first screen on an A.thaliana core collection of 25 accessions.Although most quantitative trait loci(QTLs)were highly specific to the identity of the T3E mutant(ripAC,ripAG,ripAQ,and ripU),we finely mapped a common QTL located on a cluster of nucleotide-binding domain and leucine-rich repeat(NLR)genes that exhibited structural variation.We functionally validated one of these NLRs as a susceptibility factor in response to R.solanacearum,named it Bacterial Wilt Susceptibility 1(BWS1),and cloned two alleles that conferred contrasting levels of QDR.Further characterization indicated that expression of BWS1 leads to suppression of immunity triggered by different R.solanacearum effectors.In addition,we showed a direct interaction between BWS1 and RipAC T3E,and BWS1 and SUPPRESSOR OF G2 ALLELE OF skp1(SGT1b),the latter interaction being suppressed by RipAC.Together,our results highlight a putative role for BWS1 as a quantitative susceptibility factor directly targeted by the T3E RipAC,mediating negative regulation of the SGT1-dependent immune response.

The Genetic and Molecular Basis of Plant Resistance to Pathogens

Plant pathogens have evolved numerous strategies to obtain nutritive materials from their host, and plants in turn have evolved the preformed physical and chemical barriers as well as sophisticated two-tiered immune system to combat pathogen attacks. Genetically, plant resistance to pathogens can be divided into qualitative and quantitative disease resistance, conditioned by major gene（s） and multiple genes with minor effects, respectively. Qualitative disease resistance has been mostly detected in plant defense against biotrophic pathogens, whereas quantitative disease resistance is involved in defense response to all plant pathogens, from biotrophs, hemibiotrophs to necrotrophs. Plant resistance is achieved through interception of pathogen-derived effectors and elicitation of defense response. In recent years, great progress has been made related to the molecular basis underlying host--pathogen interactions. In this review, we would like to provide an update on genetic and molecular aspects of plant resistance to pathogens.

Creation and judicious application of a wheat resistance gene atlas

Disease-resistance(R)gene cloning in wheat(Triticum aestivum)has been accelerated by the recent surge of genomic resources,facilitated by advances in sequencing technologies and bioinformatics.However,with the challenges of population growth and climate change,it is vital not only to clone and functionally characterize a few handfuls of R genes,but also to do so at a scale that would facilitate the breeding and deployment of crops that can recognize the wide range of pathogen effectors that threaten agroecosystems.Pathogen populations are continually changing,and breeders must have tools and resources available to rapidly respond to those changes if we are to safeguard our daily bread.To meet this challenge,we propose the creation of a wheat R-gene atlas by an international community of researchers and breeders.The atlas would consist of an online directory from which sources of resistance could be identified and deployed to achieve more durable resistance to the major wheat pathogens,such as wheat rusts,blotch diseases,powdery mildew,and wheat blast.We present a costed proposal detailing how the inter-acting molecular components governing disease resistance could be captured from both the host and the pathogen through biparental mapping,mutational genomics,and whole-genome association genetics.We explore options for the configuration and genotyping of diversity panels of hexaploid and tetraploid wheat,as well as their wild relatives and major pathogens,and discuss how the atlas could inform a dynamic,durable approach to R-gene deployment.Set against the current magnitude of wheat yield losses worldwide,recently estimated at 21%,this endeavor presents one route for bringing R genes from the lab to the field at a considerable speed and quantity.

The association between PPP1R3 gene polymorphisms and type 2 diabetes mellitus

Objective To detect the relationship between the polymorphism of the glycogen-targeting regulatory subunit of the skeletal muscle glycogen-associated protein phosphatase 1 (PPP1R3) gene and type 2 diabetes by case-control study. Methods We genotyped the PPP1R3 gene Asp905Tyr polymorphism and a common 3'-untranslated region AT (AU)-rich element (ARE) polymorphism in 101 type 2 diabetic patients and 101controls by oligonucleotide ligation assay (OLA) and polyacrylamide gel elecrophoresis, respectively. Results Subjects with Tyr/Tyr genotypes whose body mass index (BMI)<25 were used as the reference group. Those whose BMI25 with Asp905 had a 3.66-fold increase (95% CI: 1.48-9.06, P=0.005) in type 2 diabetes risk. No association was found between 3'UTR ARE polymorphism and type 2 diabetes mellitus (OR=1.15; 95% CI: 0.62-2.14, P=0.65). Conclusion A joint effect between the Asp905 and BMI increases the risk of type 2 diabetes, and Asp905Tyr and ARE polymorphism of PPP1R3 gene are not the major diabetogenic gene variants in Chinese population.

Plant NLRs: The Whistleblowers of Plant Immunity

The study of plant diseases is almost as old as agriculture itself. Advancements in molecular biology havegiven us much more insight into the plant immune system and how it detects the many pathogens plantsmay encounter. Members of the primary family of plant resistance (R) proteins, NLRs, contain three distinctdomains, and appear to use several different mechanisms to recognize pathogen effectors and trigger immunity. Understanding the molecular process of NLR recognition and activation has been greatly aided byadvancements in structural studies, with ZAR1 recently becoming the first full-length NLR to be visualized.Genetic and biochemical analysis identified many critical components for NLR activation and homeostasiscontrol. The increased study of helper NLRs has also provided insights into the downstream signaling pathways of NLRs. This review summarizes the progress in the last decades on plant NLR research, focusing onthe mechanistic understanding that has been achieved.

The chromosome-level genome assembly of Astragalus sinicus and comparative genomic analyses provide new resources and insights for understanding legume-rhizobial interactions

The legume species Astragalus sinicus(Chinese milk vetch[CMV])has been widely cultivated for centuries in southern China as one of the most important green manures/cover crops for improving rice productivity and preventing soil degeneration.In this study,we generated the first chromosome-scale reference genome of CMV by combining PacBio and Illumina sequencing with high-throughput chromatin conformation capture(Hi-C)technology.The CMV genome was 595.52 Mb in length,with a contig N50 size of 1.50 Mb.Long terminal repeats(LTRs)had been amplified and contributed to genome size expansion in CMV.CMV has undergone two whole-genome duplication(WGD)events,and the genes retained after the WGD shared by Papilionoideae species shaped the rhizobial symbiosis and the hormonal regulation of nodulation.The chalcone synthase(CHS)gene family was expanded and was expressed primarily in the roots of CMV.Intriguingly,we found that resistance genes were more highly expressed in roots than in nodules of legume species,suggesting that their expression may be increased to bolster plant immunity in roots to cope with pathogen infection in legumes.Our work sheds light on the genetic basis of nodulation and symbiosis in CMV and provides a benchmark for accelerating genetic research and molecular breeding in the future.