DNA Extraction from a Single Seed for Marker-Assisted Selection in Squash

Marker-assisted selection is an important tool in squash (Cucurbita species) breeding. A seed-based genotyping system would not only allow selection of desirable individuals prior to planting, but also reduce the cost associated with leaf-derived DNA genotyping, such as the need for greenhouse facilities and ultra-low-temperature storage freezers. A robust seed-based genotyping system requires a non-destructive sampling method and DNA of sufficient quantity and quality for marker-assisted selection. In the current study, six cultivars representing Cucurbita pepo (Black Beauty and Yellow Crookneck), C. moschata (Butterbush and Fairytale), and C. maxima (Buttercup and Big Max) were used to develop a suitable seed-based genotyping system for squash. Seed chips for DNA extraction were sampled by removing 1/3 of the distal end, while the remnant seed-embryos were sowed to assess germination potential. Four extraction methods including two column-based commercial kits (CTAB and ENZA) and two detergent-based conventional methods (CTAB and SDS) were assessed for DNA quality and quantity. Utility of extracted DNA for downstream applications was tested by genotyping with SSR and SNP markers. There was no significant difference in germination percentage between whole and cut seeds across the six cultivars. The average DNA concentration across methods ranged from 11.6 ng/μL to 62.6 ng/μl, while the DNA quality (A260/280) ranged from 0.89 to 1.95. Although DNA was obtained for all the extraction methods, only EZNA and Favorgen methods yielded DNA of sufficient quality for marker-assisted selection.

Genetic Variation among <i>Cucurbita pepo</i>Accessions Varying in Seed Nutrition and Seed Size

Pumpkin seed (Cucurbita pepo L.) is a nutritionally valuable food and a significant source of income globally. Pumpkin seeds are rich in oil, protein, unsaturated fatty acids and tocopherols, which are associated with improved human health. Understanding the genetic diversity among pumpkin accessions varying in seed nutrition traits is necessary for designing sound breeding strategies for developing superior cultivars. In the current study, 26 simple sequence repeats (SSR) markers were used to assess genetic relatedness among 29 C. pepo accessions varying in seed oil, seed protein, seed-coat phenotype, seed size and fatty acid composition. The SSR markers revealed 102 alleles averaging 3.92 alleles per loci and mean polymorphic information content (PIC) of 0.44. Eleven of the markers had a PIC of ≥0.5. Ward dendrogram and principle component analysis based on seed traits grouped the genotypes into two major clusters corresponding to subspecies pepo and texana, with all the reduced-hull accessions grouping within the former. Collectively, this data suggests wide phenotypic (seed traits) and genotypic variation within C. pepo that may be exploited to develop superior reduced-hull cultivars.

Tunable CO_(2)enrichment on functionalized Au surface for enhanced CO_(2)electroreduction

Electrochemical conversion of carbon dioxide(CO_(2))to higher-value products provides a forward-looking way to solve the problems of environmental pollution and energy shortage.However,the low solubility of CO_(2)in aqueous electrolytes,sluggish kinetics,and low selectivity hamper the efficient conversion of CO_(2).Here,we report a Au-based hybrid nanomaterial by modifying Au nanoparticles(NPs)with the macrocyclic molecule cucurbit[6]uril(Au@CB[6]).Au@CB[6]displays the optimal selectivity of CO,with the highest CO Faraday efficiency(FECO)reaching 99.50%at−0.6 V vs.reversible hydrogen electrode(RHE).The partial current density of CO formed by Au@CB[6]increases dramatically,as 3.18 mA/cm2 at−0.6 V,which is more than ten times as that of oleylamine-coated Au NPs(Au@OAm,0.31 mA/cm2).Operando electrochemical measurement combined with density functional theory(DFT)calculations reveals that CB[6]can gather CO_(2)and lead the increased local CO_(2)concentration near metal interface,which realizes significantly enhanced electrochemical CO_(2)reduction reaction(CO_(2)RR)performance.

Expeditious Coordination-Driven Construction of Hierarchically Nanoporous Barium Salts

Organic moieties-derived salts with permanent porosity and polarized channels have shown unique features and attractive performance in the field of adsorption,separation,and conduction.However,state-of-the-art organic salts generally rely on ionic interaction and hydrogen bonding formation to maintain the porous channels.The synthesis of organic moiety-derived saltswith permanent accessible pores even after removal of the trapped guest molecules,and without the constraint of hydrogen bonding formation still remains a great challenge.Herein,we present an expeditious construction pathway to generate hierarchically nanoporous barium salts without hydrogen bonding formation.The strong ionic interaction of the bariumcation and sulfonate anions led to rapid reaction equilibrium(∼2 min),affording diverse barium-derived ionic polymer(Ba-IP)with permanent porosity and highly polarized channels.The produced Ba-IP materials with abundant cations and anions displayed high CO_(2)/N2 and CO_(2)/CH_(4)separation performance,with the selectivities reaching up to 89.5 and 280,respectively,at 273 K,surpassingmost of the organic polymers functionalized by ionic moieties.

Effects of Plant Growth-Promoting Rhizobacteria and N Source on Plant Growth and N and P Uptake by Tomato Grown on Calcareous Soils

Introducing specific microorganisms into the soil ecological system is an important strategy for improving nutrient use efficiency.Two pot experiments were conducted in the greenhouse from December 3, 2012 to January 25, 2013(Experiment 1) and March 11 to April 23, 2013(Experiment 2) to evaluate the effect of nitrogen(N) source and inoculation with plant growth-promoting rhizobacteria(PGPR) on plant growth and N and phosphorus(P) uptake in tomato(Lycopersicon esculentum Mill.) grown on calcareous soils from South Florida, USA.Treatments included urea, controlled release urea(a controlled release fertilizer, CRF) each at low and high N rates and with or without inoculation of PGPR.A mixture of PGPR strains Bacillus amyloliquefaciens IN937 a and Bacillus pumilus T4 was applied to the soil during growing periods of tomato.Treatments with PGPR inoculation increased plant height compared to treatments without PGPR in both experiments.Inoculation with PGPR increased shoot dry weight and shoot N uptake for the same N rate and N source.In both experiments, only at high N rate, CRF and urea treatments with PGPR had significantly(P < 0.05)greater shoot biomass than those without PGPR.Only at high N rate, CRF treatment with PGPR significantly increased shoot N uptake by 39.0% and 10.3% compared to that without PGPR in Experiments 1 and 2, respectively.Meanwhile, presence of PGPR in the soil increased shoot P uptake for all treatments in Experiment 1 and for most treatments in Experiment 2.In Experiment 1, only at low N rate, CRF treatment with PGPR significantly increased shoot P uptake compared with that without PGPR.In Experiment2, a significant increase in shoot P uptake by inoculation of PGPR was only observed in CRF treatment at high N rate.Results from this study indicate that inoculation with PGPR may increase plant growth and N and P uptake by tomato grown on calcareous soils.However, the effect of PGPR varied and was influenced by many factors such as N source, N rate, and soil fertility.Further investigations are warranted to confirm the effect of PGPR under different soil conditions.