Identification of powdery mildew resistance loci in wheat by integrating genome-wide association study(GWAS) and linkage mapping

Wheat powdery mildew(Blumeria graminis f.sp.tritici, Bgt) is a disease of increasing importance globally due to the adoption of high yielding varieties and modern sustainable farming technologies.Growing resistant cultivars is a preferred approach to managing this disease, and novel powdery mildew resistance genes are urgently needed for new cultivar development.A genome-wide association study was performed on a panel of 1292 wheat landraces and historical cultivars using 5011 single nucleotide polymorphism(SNP)markers.The association panel was evaluated for reactions to three Bgt inoculants, OKS(14)-B-3-1, OKS(14)-C-2-1, and Bgt15.Linkage disequilibrum(LD) analysis indicated that genome-wide LD decayed to 0.1 at 23 Mb, and population structure analysis revealed seven subgroups in the panel.Association analysis using a mixed linear model(MLM) identified three loci for powdery mildew resistance on chromosome 2 B, designated QPm.stars-2BL1,QPm.stars-2BL2, and QPm.stars-2BL3.To evaluate the efficacy of GWAS in gene discovery,QPm.stars-2BL2 was validated using F2 and F2:3 populations derived from PI420646 × OK1059060-126135-3.Linkage analysis delimited the powdery mildew resistance gene in PI 420646 to an interval where QPm.stars-2BL2 was located, lending credence to the GWAS results.QPm.stars-2BL1 and QPm.stars-2BL3, which were associated with four SNPs located at 457.7–461.7 Mb and two SNPs located at 696.6–715.9 Mb in the Chinese Spring reference IWGSC RefSeq v1.0, respectively, are likely novel loci for powdery mildew resistance and can be used in wheat breeding to improve powdery mildew resistance.

Growth and Yield Responses of Switchgrass Ecotypes to Temperature

Varietal differences of switchgrass in growth and development, biomass yield and partitioning in response to temperature are not well documented. A study was conducted to quantify the effect of temperature on growth, development, and feedstock quality of switchgrass cultivars, and to determine differences between upland and lowland switchgrass. Two lowland (“Alamo” and “Kanlow”) and two upland (“Caddo” and “Cave-in-Rock”) cultivars of switchgrass were grown in pots filled with pure, fine sand in growth chambers. Four different temperature treatments of 23℃/15℃, 28℃/20℃, 33℃/25℃, and 38℃/30℃ with 14/10 hours day/night were imposed at four leaf stage. High temperature significantly decreased the biomass yield across all cultivars. Stem elongation rate (SER) and leaf elongation rate (LER) decreased at the highest temperature treatment but lowland cultivars had significantly higher SER and LER across the temperature treatments. Upland cultivars produced more tillers across the temperature treatment. Both shoot/root and leaf/stem ratios increased under the highest temperature in all cultivars, but upland cultivars partitioned more to the leaf and root at higher temperature. Concentration of cellulose decreased at the highest temperature but temperature had no effect on lignin concentration of leaf and stem biomass. In conclusion, although none of the cultivars studied showed strong tolerance to high temperature, differences were observed for many traits of switchgrass in response to temperature.

Heritability estimates for seed yield and its components in Cynodon dactylon var. dactylon (L.) Pers.

Bermudagrass[Cynodon dactylon var.dactylon(L.)Pers.]is a major warm-season turf and forage grass worldwide.Seed yield is an important trait targeted for improvement in bermudagrass breeding programs because of the increased interest in seed-propagated cultivars.Understanding the nature of genetic variation for seed yield and its components in bermudagrass would aid the development of seed-propagated cultivars.The objective of this study was to estimate the genetic variation and narrow-sense heritability for seed yield and its two major components,inflorescences prolificacy and seed set percentage in bermudagrass.Twenty-five half-sib families and their respective clonal parents were evaluated at two Oklahoma locations,Perkins and Stillwater(Oklahoma,USA),over two years.Half-sib families were different for seed yield,inflorescences prolificacy and seed set percentage,indicating the expression of additive genes in controlling these traits.Family×location effects were observed for seed set percentage and seed yield.All three traits showed family×year interaction effects.There was a significant family×location×year interaction in inflorescences prolificacy and seed set percentage.Narrow-sense heritability estimates for seed yield was 0.18 based on variance component analysis among half-sib families and ranged from 0.26 to 0.68 based on parent-offspring regressions,indicating genetic complexity of seed yield.Heritability estimates were moderate(0.30−0.55)for inflorescences prolificacy and moderate to relatively high(0.41−0.78)for seed set percentage.The results indicate that sufficient magnitudes of additive genetic variation for seed set percentage and inflorescence prolificacy permit positive response to selection and conventional progeny-based genotypic evaluation is necessary for seed yield improvement.Citation:Tan C,Wu Y,Taliaferro CM,Bell GE,Martin DL,et al.2022.Heritability estimates for seed yield and its components in Cynodon dactylon var.

Preparation of norovirus GII loop mediated isothermal amplification freeze-drying microsphere reagents and its application in an on-site integrated rapid detection platform

Norovirus is an infectious disease that can cause non-bacterial gastroenteritis,which has a low infectious dose,rapid onset,and strong transmission ability;therefore,rapid and sensitive detection is essential to reduce the transmission of gastroenteritis.In the study,a norovirus GII loop-mediated isothermal amplification assay was developed and prepared into freeze-drying microspheres,and a closed-cassette-based,integrated,reagent-ambient storage,on-site instant detection platform for norovirus GII was constructed using a commercial,fully automated nucleic acid analyzer with integrated magnetic bearing based nuclear acid extraction and nucleic acid detection,with a sensitivity of 10 copies/μL,with no cross-reactivity with other 5 viruses.For 28 simulated samples,the integrated assay platform was consistent with the experimental results of reverse transcription-quantitative polymerase chain reaction(RT-qPCR)assays after conventional laboratory nucleic acid extraction.The entire process can be finished in about 1 h,which is ideal for immediate rapid detection.

Research progress of severe acute respiratory syndrome coronavirus 2 on aerosol collection and detection

The outbreak of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)in late 2019 has negatively affected people's lives and productivity.Because the mode of transmission of SARS-CoV-2 is of great concern,this review discusses the sources of virus aerosols and possible transmission routes.First,we discuss virus aerosol collection methods,including natural sedimentation,solid impact,liquid impact,centrifugal,cyclone and electrostatic adsorption methods.Then,we review common virus aerosol detection methods,including virus culture,metabolic detection,nucleic acid-based detection and immunology-based detection methods.Finally,possible solutions for the detection of SARS-CoV-2 aerosols are introduced.Point-of-care testing has long been a focus of attention.In the near future,the development of an instrument that integrates sampling and output results will enable the real-time,automatic monitoring of patients.

Novel aerosol detection platform for SARS–CoV–2:Based on specific magnetic nanoparticles adsorption sampling and digital droplet PCR detection

The SARS–CoV–2 virus is released from an infectious source(such as a sick person)and adsorbed on aerosols,which can form pathogenic microorganism aerosols,which can affect human health through airborne transmission.Efficient sampling and accurate detection of microorganisms in aerosols are the premise and basis for studying their properties and evaluating their hazard.In this study,we built a set of sub-micron aerosol detection platform,and carried out a simulation experiment on the SARS–CoV–2 aerosol in the air by wet-wall cyclone combined with immunomagnetic nanoparticle adsorption sampling and ddPCR.The feasibility of the system in aerosol detection was verified,and the influencing factors in the detection process were experimentally tested.As a result,the sampling efficiency was 29.77%,and extraction efficiency was 98.57%.The minimum detection limit per unit volume of aerosols was 250 copies(102copies/m L,concentration factor 2.5).

Yield-height correlation and QTL localization for plant height in two lowland switchgrass populations

Switchgrass(Panicum virgatum L.), as a model herbaceous crop species for bioenergy production,is targeted to improve biomass yield and feedstock quality.Plant height is a major component contributing to biomass yield. Accordingly, the objectives of this research were to analyze phenotypic variation for biomass and plant height and the association between them and to localize associated plant height QTLs. Two lowland switchgrass mapping populations, one selfed and another hybrid population established in the field at Perkins and Stillwater,Oklahoma, were deployed in the experiment for two years post establishment. Large genetic variation existed for plant biomass and height within the two populations. Plant height was positively correlated with biomass yield in the selfed population(r = 0.39, P < 0.0001) and the hybrid population(r = 0.41, P < 0.0001). In the selfed population,a joint analysis across all environments revealed 10 QTLs and separate analysis for each environment, collectively revealed 39 QTLs related to plant height. In the hybrid population, the joint analysis across overall environments revealed 35 QTLs and the separate analysis for each environment revealed 38 QTLs. The findings of this research contribute new information about the genetic control for plant height and will be useful for future plant breeding and genetic improvement programs in lowland switchgrass.