NPR1 as a transgenic crop protection strategy in horticultural species

The NPR1(NONEXPRESSOR OF PATHOGENESIS RELATED GENES1)gene has a central role in the long-lasting,broad-spectrum defense response known as systemic acquired resistance(SAR).When overexpressed in a transgenic context in Arabidopsis thaliana,this gene enhances resistance to a number of biotic and abiotic stresses.Its position as a key regulator of defense across diverse plant species makes NPR1 a strong candidate gene for genetic engineering disease and stress tolerance into other crops.High-value horticultural crops face many new challenges from pests and pathogens,and their emergence exceeds the pace of traditional breeding,making the application of NPR1-based strategies potentially useful in fruit and vegetable crops.However,plants overexpressing NPR1 occasionally present detrimental morphological traits that make its application less attractive.The practical utility of NPR-based approaches will be a balance of resistance gains versus other losses.In this review,we summarize the progress on the understanding of NPR1-centered applications in horticultural and other crop plants.We also discuss the effect of the ectopic expression of the A.thaliana NPR1 gene and its orthologs in crop plants and outline the future challenges of using NPR1 in agricultural applications.

Direct somatic embryogenesis and related gene expression networks in leaf explants of Hippeastrum ‘Bangkok Rose’

Hippeastrum, a highly diverse genus in the Amaryllidaceae family, is a valuable ornamental bulbous flowering plant. Somatic embryogenesis(SE) is an efficient method for mass production of Hippeastrum plantlets. Previous studies have been devoted to the in vitro propagation of Hippeastrum, but the SE and its regulatory networks are rarely reported. In this study, we established a direct SE method of Hippeastrum Bangkok Rose' using leaf bases as explants. MS supplemented with 1.00 mg·L^(-1)NAA +1.00 mg·L^(-1)KT + 0.25 mg·L^(-1)TDZ was the optimal medium for SE. Histological observations showed that the bipolar somatic embryo originated from the epidermal cell layer and underwent initiation,globular, scutellar and coleoptile stages. During SE, endogenous hormones of IAA, CTK, ABA, and SA were highly accumulated. Transcriptomic analysis revealed the genes encoding auxin biosynthesis/metabolic enzymes and efflux carriers were induced, while the auxin receptor of TIR1 and ARF transcriptional repressor of Aux/IAA were down-regulated and up-regulated, respectively, leading to suppression of auxin signaling. In contrast, cytokine signaling was promoted at the early stage of SE, as biosynthesis, transport, and signaling components were up-regulated.Various stress-related genes were up-regulated at the early or late stages of SE. Chromatin remodeling could also be dynamically regulated via distinct expression enzymes that control histone methylation and acetylation during SE. Moreover, key SE regulators, including WOXs and SERKs were highly expressed along with SE. Overall, the present study provides insights into the SE regulatory mechanisms of the Hippeastrum.

乙烯诱导西瓜果实的水渍化败坏(英文)

为了研究乙烯在西瓜(Citrullus lanatusThunb.Mansfeld)果实水渍化败坏过程中的作用,先将果实在5μL/L 1-甲基环丙烯(1-MCP)气体中处理18 h,然后在50 μL/L乙烯和20℃温度下贮藏。西瓜果实对乙烯处理的最初反应表现为胎座组织的电导率和游离汁液增加,同时出现组织软化和水渍化。水渍化的症状最初在靠近花萼端的内果皮中发生,在乙烯处理的第2天开始出现,ACC合成酶(ACS)和ACC氧化酶(ACO)的活性明显提高。1-MCP单独处理不产生任何明显的作用,但是会完全抑制外源乙烯诱导的水渍化败坏。没有经过 乙烯处理的西瓜果实,贮藏2 d以后出现呼吸强度和乙烯释放量的高峰,10 d以后水渍化现象也零星出现。这些结果和1-MCP的预防效果说明,西瓜果实的水渍化败坏是一种由乙烯诱导的衰老现象。

Sequential light programs shape kale (Brassica napus) sproutappearance and alter metabolic and nutrient content

Different light wavelengths have specific effects on plant growth and development.Narrow-bandwidth light-emitting diode(LED)lighting may be used to directionally manipulate size,color and metabolites in high-value fruits and vegetables.In this report,Red Russian kale(Brassica napus)seedlings were grown under specific light conditions and analyzed for photomorphogenic responses,pigment accumulation and nutraceutical content.The results showed that this genotype responds predictably to darkness,blue and red light,with suppression of hypocotyl elongation,development of pigments and changes in specific metabolites.However,these seedlings were relatively hypersensitive to far-red light,leading to uncharacteristically short hypocotyls and high pigment accumulation,even after growth under very low fluence rates(,1 mmol m^(-2) s^(-1)).General antioxidant levels and aliphatic glucosinolates are elevated by far-red light treatments.Sequential treatments of darkness,blue light,red light and far-red light were applied throughout sprout development to alter final product quality.These results indicate that sequential treatment with narrow-bandwidth light may be used to affect key economically important traits in high-value crops.

The USDA cucumber (Cucumis sativus L.) collection: genetic diversity, population structure, genome-wide association studies, and core collection development

Germplasm collections are a crucial resource to conserve natural genetic diversity and provide a source of novel traits essential for sustained crop improvement.Optimal collection,preservation and utilization of these materials depends upon knowledge of the genetic variation present within the collection.Here we use the high-throughput genotyping-by-sequencing(GBS)technology to characterize the United States National Plant Germplasm System(NPGS)collection of cucumber(Cucumis sativus L.).The GBS data,derived from 1234 cucumber accessions,provided more than 23 K high-quality single-nucleotide polymorphisms(SNPs)that are well distributed at high density in the genome(~1 SNP/10.6 kb).The SNP markers were used to characterize genetic diversity,population structure,phylogenetic relationships,linkage disequilibrium,and population differentiation of the NPGS cucumber collection.These results,providing detailed genetic analysis of the U.S.cucumber collection,complement NPGS descriptive information regarding geographic origin and phenotypic characterization.We also identified genome regions significantly associated with 13 horticulturally important traits through genome-wide association studies(GWAS).Finally,we developed a molecularly informed,publicly accessible core collection of 395 accessions that represents at least 96%of the genetic variation present in the NPGS.Collectively,the information obtained from the GBS data enabled deep insight into the diversity present and genetic relationships among accessions within the collection,and will provide a valuable resource for genetic analyses,gene discovery,crop improvement,and germplasm preservation.

A survey of FLS2 genes from multiple citrus species identifies candidates for enhancing disease resistance to Xanthomonas citri ssp. citri.

Pathogen-associated molecular patterns(PAMPs)-triggered immunity(PTI)is an important component of plant innate immunity.In a previous study,we showed that the PAMP flg22 from Xanthomonas citri ssp.citri(Xflg22),the causal agent of citrus canker,induced PTI in citrus,which correlated with the observed levels of canker resistance.Here,we identified and sequenced two bacterial flagellin/flg22 receptors(FLS2-1 and FLS2-2)from‘Duncan’grapefruit(Citrus paradisi,CpFLS2-1 and CpFLS2-2)and‘Sun Chu Sha’mandarin(C.reticulata,CrFLS2-1 and CrFLS2-2).We were able to isolate only one FLS2 from‘Nagami’kumquat(Fortunella margarita,FmFLS2-1)and gene flanking sequences suggest a rearrangement event that resulted in the deletion of FLS2-2 from the genome.Phylogenetic analysis,gene structure and presence of critical amino acid domains all indicate we identified the true FLS2 genes in citrus.FLS2-2 was more transcriptionally responsive to Xflg22 than FLS2-1,with induced expression levels higher in canker-resistant citrus than in susceptible ones.Interestingly,‘Nagami’kumquat showed the highest FLS2-1 steady-state expression levels,although it was not induced by Xflg22.We selected FmFLS2-1,CrFLS2-2 and CpFLS2-2 to further evaluate their capacity to enhance bacterial resistance using Agrobacterium-mediated transient expression assays.Both FmFLS2-1 and CrFLS2-2,the two proteins from canker-resistant species,conferred stronger Xflg22 responses and reduced canker symptoms in leaves of the susceptible grapefruit genotype.These two citrus genes will be useful resources to enhance PTI and achieve resistance against canker and possibly other bacterial pathogens in susceptible citrus types.

Sensory sacrifices when we mass-produce mass produce

Plant breeders have been extremely successful at driving genetic improvements in crops.However,‘improvements’are truly a question of perspective.Over the last one-hundred years most plant genetic innovations have been driven by industry demand.Larger fruits,heavier yields,uniformity,increased resistance to disease and better shipping quality are just a few of the traits that have ensured profits on the farm and affordable food for consumers.However,these milestones have come at the expense of sensory qualities,which have been sacrificed in exchange for practical production objectives.With a base of industry-sufficient genetics,today’s breeders can now turn to the consumer for guidance in defining critical desires.New approaches to plant breeding start with the analysis of consumer preferences,and then merge them with modern genomics and analytical chemistry tools.The result is the next generation of crops that meet supply chain demands while presenting improvements in flavor,nutrition,color,aroma and texture.This review analyzes the approach of consumer-assisted selection as it has been applied to tomato and strawberry,two complementary annual crops that have been intensively bred to meet industry expectations.Current breeding efforts start with the consumer,with the objective of reclaiming lost sensory qualities.

Strawberry sweetness and consumer preference are enhanced by specific volatile compounds

Breeding crops for improved flavor is challenging due to the high cost of sensory evaluation and the difficulty of connecting sensory experience to chemical composition.The main goal of this study was to identify the chemical drivers of sweetness and consumer liking for fresh strawberries(Fragaria×ananassa).Fruit of 148 strawberry samples from cultivars and breeding selections were grown and harvested over seven years and were subjected to both sensory and chemical analyses.Each panel consisted of at least 100 consumers,resulting in more than 15,000 sensory data points per descriptor.Three sugars,two acids and 113 volatile compounds were quantified.Consumer liking was highly associated with sweetness intensity,texture liking,and flavor intensity,but not sourness intensity.Partial least square analyses revealed 20 volatile compounds that increased sweetness perception independently of sugars;18 volatiles that increased liking independently of sugars;and 15 volatile compounds that had positive effects on both.Machine learning-based predictive models including sugars,acids,and volatiles explained at least 25%more variation in sweetness and liking than models accounting for sugars and acids only.Volatile compounds such asγ-dodecalactone;5-hepten-2-one,6-methyl;and multiple medium-chain fatty acid esters may serve as targets for breeding or quality control attributes for strawberry products.A genetic association study identified two loci controlling ester production,both on linkage group 6 A.Co-segregating makers in these regions can be used for increasing multiple esters simultaneously.This study demonstrates a paradigm for improvement of fruit sweetness and flavor in which consumers drive the identification of the most important chemical targets,which in turn drives the discovery of genetic targets for marker-assisted breeding.

Comparative transcriptome analysis during early fruit development between three seedy citrus genotypes and their seedless mutants

Identification of genes with differential transcript abundance(GDTA)in seedless mutants may enhance understanding of seedless citrus development.Transcriptome analysis was conducted at three time points during early fruit development(Phase 1)of three seedy citrus genotypes:Fallglo(Bower citrus hybrid(Citrus reticulata×C.reticulata×C.paradisi)×Temple(C.reticulata×C.sinensis)),grapefruit(C.paradisi),Pineapple sweet orange(C.sinensis),and their seedless mutants.Seed abortion in seedless mutants was observed at 26 days post anthesis(Time point 2).Affymetrix transcriptomic analysis revealed 359 to 1077 probe sets with differential transcript abundance in the comparison of seedless versus seedy fruits for each citrus genotypes and time points.The GDTA identified by 18 microarray probe sets were validated by qPCR.Hierarchical clustering analysis revealed a range of GDTA associated with development,hormone and protein metabolism,all of which may reflect genes associated with seedless fruit development.There were 14,9 and 12 genes found exhibiting similar abundance ratios in all three seedless versus seedy genotype comparisons at time point 1,2 and 3,respectively.Among those genes were genes coding for an aspartic protease and a cysteine protease,which may play important roles in seedless fruit development.New insights into seedless citrus fruit development may contribute to biotech approaches to create seedless cultivars.

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.

The strawberry genome:a complicated past and promising future

Within the juicy red flesh of the commercial strawberry lies a deep history that spans at least three continents and hundreds of thousands of years.The genetic heritage of this prized dessert fruit was crafted by nature,with its modern improvement driven by the indigenous Mapuche people of South America,a seafaring a French spy,and a plant-loving teenager that gathered fruits to present to a king.The many stories that punctuate the history of the modern strawberry relate to its contemporary cultivation as well as origins that span a significant portion of the globe1,2.

Weed Control Efficacy and Citrus Response to Flazasulfuron Applied Alone or in Combination with Other Herbicides

Field experiments were conducted to evaluate the phytotoxicity of flazasulfuron on citrus species and efficacy on weeds when applied alone or in combination with other herbicides. Grapefruit was the most sensitive and tangerine was the least sensitive to flazasulfuron. Injury to grapefruit was 70% with the application of flazasulfuron at 0.20 kg a.i. ha–1 at 60 DAT and was reduced (5%) when flazasulfuron at 0.05 kg a.i. ha–1 was tank mixed with glyphosate at 0.84 kg·a.i.· ha–1. Flazasulfuron alone at all rates did not control grass weeds and common ragweed. Florida/Brazil pusley was moderately controlled with high rates of flazasulfuron from 30 to 45 DAT;however, control did not exceed 75%. There was good control of Spanishneedles (78% - 85%) and horseweed (73% - 81%) with flazasulfuron at all rates at 30 DAT but control declined later in the season. Tank mix of flazasulfuron with glyphosate improved flazasulfuron efficacy on grass and broadleaf weeds. Flazasulfuron at 0.07 kg a.i. ha–1 plus glyphosate at 1.70 kg a.i. ha–1 was more effective in controlling grass weeds (83%) at 60 DAT and provided the highest control (79%) of Florida/Brazil pusley at 45 DAT. There was excellent control (75% to 94%) of Spanishneedles and adequate control of eastern black nightshade and common ragweed with flazasulfuron tank mixed with glyphosate or diuron. This study showed that flazasulfuron alone does not adequately control grasses and some broadleaf weeds in citrus and tank mixing it with glyphosate or diuron improved flazasulfuron’s efficacy. However, injury to grapefruit was observed at rates which effectively controlled weeds. Further studies are needed to determine the most suitable flazasulfuron rate that could be used to manage weeds in grapefruit.

The impact of Persian oak (Quercus brantii Lindl.) on soil characteristics in a declining forest

Root activity has an important impact on soil development but we have little knowledge of the interaction of the root zone and soil genetic horizons.The aim of this investigation was to study the interactions between soil chemical characteristics and root zone processes in a declining Persian oak forest(Quercus brantii Lindl.).A randomized complete block design was used to investigate the long-term eff ect of Persian oak on soil horizons,and the chemical and biological properties in two soil zones(under and outside the canopy).Results indicate that the rhizosphere zone had signifi cantly higher total organic carbon(TOC)than outside the canopy soil in the upper soil horizons.In subsurface horizons,water-extractable organic carbon values were signifi cantly higher in rhizosphere than in non-rhizospheric zone.Microbial biomass carbon(MBC)values in the rhizospheric zone decreased from the fi rst to the second horizon.The MBC/TOC ratio indicated signifi-cant diff erences between the rhizosphere and soils outside of the canopy,with the exception of the subsurface horizon.In the subsurface horizon of the rhizosphere,there was greater respiration of organic carbon(ΣCO 2/TOC)than in outside of canopy soil.In addition,root processes infl uenced pH,nitrogen fractions,and availability of phosphorus,potassium,iron,zinc and manganese.Diff erences in soil characteristics between rhizospheric and non-rhizospheric zones were signifi cant in surface horizons due to higher root density than in deeper soil layers.The fi ndings indicate that Persian oak(Quercus brantii Lindl.)roots infl uenced the main soil chemical properties,even in calcareous soils.

Effect of Various Soil Media on Disease Severity of <i>Fusarium</i>Wilt in Watermelon

Fusarium wilt is a major disease of watermelon (Citrullus lanatus) caused by Fusarium oxysporum f. sp. niveum (Fon). Use of host resistance is the most effective management strategy for the disease, and a major objective for breeding programs. Screening assays rely on the ability to discriminate resistant and susceptible genotypes in segregating populations. However, complex interactions between Fon and the soil environment can influence symptom development and disease severity rating. In the current study, severity of Fusarium wilt (race 1) in sand-peat (1:1 v/v), sand-perlite (1:1), sand-peat-vermiculite (4:1:1), peat-perlite (1:1) and Fafard 3B potting media was compared among five watermelon cultivars: Calhoun Gray (resistant), SunSugar (resistant), Allsweet (moderately resistant), Sugar Baby (susceptible) and Charleston Gray (susceptible). Plant biomass (average dry weight/plant) was lowest in peat-perlite (1.67 g) and sand-peat (2.16 g), and was significantly different (α = 0.05) from that of sand-perlite (3.48 g), sand-peat-vermiculite (4.94 g) and Fafard 3B (6.90 g). Conversely, disease severity [area under disease progress curve (AUDPC)] across cultivars was significantly higher in peat-perlite (AUDPC = 62.96) and sand-peat (AUDPC = 40.87), than in sand-perlite (AUDPC = 11.55), sand-peat-vermiculite (AUDPC = 10.67) and Fafard 3B (AUDPC = 9.29). Consistent discrimination (α = 0.05) of resistant and susceptible cultivars was realized in sand-peat-vermiculite and Fafard 3B, but was not possible in peat-perlite, sand-peat and sand-perlite. Collectively, these findings support suitability of sand-peat-vermiculite and Fafard 3B for routine screening of Fusarium wilt resistance in watermelon.

<i>Agrobacterium</i>-Mediated Transformation of Mexican Lime (<i>Citrus aurantifolia</i>Swingle) Using Optimized Systems for Epicotyls and Cotyledons

Transgenic Mexican lime (Citrus aurantifolia Swingle) was produced through two explant sources, each using systems previously optimized for each source. One used epicotyls segments, which was the predominant explant for transgenic Citrus production following co-cultivation with Agrobacterium, and has a well-established protocol. The other procedure used embryo cotyledons from mature seeds, which was developed in our lab as an alternative for stable Citrus transformation. Cotyledon transformation and regeneration protocols were optimized by comparing variables in culture medium composition on shoot regeneration and four parameters in transient transformation. The optimized protocols were compared, and frequency of regeneration, frequency of transgenic plant-recovery and stable transformation efficiency indicated the superiority of the cotyledon protocol for Agrobacterium-mediated genetic transformation in Mexican lime. The tissue choice resulted in marked improvement in shoot regeneration (14.1% of explants producing shoots in epicotyls;55.8% in cotyledons), stable transformation frequency (11.4% of epicotyls explants;40.2% in cotyledons), and frequency of transgenic plant-recovery (37.9% in epicotyl explants;92.6% in cotyledons). Thus, easy availability of explants using embryo cotyledons from mature seeds, technical simplicity, shortening of transformation time-course, and higher transformation and regeneration frequencies makes this new system an attractive alternative over the previously published Citrus transformation protocols. In the course of this project, we generated Mexican lime with a Recombinase Mediated Exchange Cassette landing pad, which was designed for stacking transgenes.

Low-Cost Strategies for Development of Molecular Markers Linked to Agronomic Traits in<i>Prunus</i>

Evaluation of agronomic traits in Prunus breeding programs is a tedious process because of the long juvenile period of trees, the influence of juvenility and the existence of climatic factors affecting the expression of the trait. For these reasons, marker-assisted selection (MAS) strategies are particularly useful in these cases. The objective of this work is the analysis of alternative low- cost strategies for development of molecular markers linked to agronomic traits in Prunus including the application of modified Bulked segregant analysis (BSA) using Simple sequence repeat (SSRs) markers and the application of Random amplified polymorphism microsatellite (RAMP) markers. First BSA results showed that two SSR loci were found to be tightly linked to flowering time in almond. On the other hand, RAMP analysis has been demonstrated to be a potentially valuable molecular marker for the study of genetic relationships in Prunus. Results showed the dominant nature of these markers with a great abundance and transferability although with a reduced polymorphism. In addition, RAMP application in F1 progenies showed its suitability for molecular characterization and mapping, and later Quantitative trait loci (QTL) or BSA analysis.

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.

Blueberry and cranberry pangenomes as a resource for future genetic studies and breeding efforts

Domestication of cranberry and blueberry began in the United States in the early 1800s and 1900s,respectively,and in part owing to their f lavors and health-promoting benefits are now cultivated and consumed worldwide.The industry continues to face a wide variety of production challenges(e.g.disease pressures),as well as a demand for higher-yielding cultivars with improved fruit quality characteristics.Unfortunately,molecular tools to help guide breeding efforts for these species have been relatively limited compared with those for other high-value crops.Here,we describe the construction and analysis of the first pangenome for both blueberry and cranberry.Our analysis of these pangenomes revealed both crops exhibit great genetic diversity,including the presence-absence variation of 48.4%genes in highbush blueberry and 47.0%genes in cranberry.Auxiliary genes,those not shared by all cultivars,are significantly enriched with molecular functions associated with disease resistance and the biosynthesis of specialized metabolites,including compounds previously associated with improving fruit quality traits.The discovery of thousands of genes,not present in the previous reference genomes for blueberry and cranberry,will serve as the basis of future research and as potential targets for future breeding efforts.The pangenome,as a multiple-sequence alignment,as well as individual annotated genomes,are publicly available for analysis on the Genome Database for Vaccinium-a curated and integrated web-based relational database.Lastly,the core-gene predictions from the pangenomes will serve useful to develop a community genotyping platform to guide future molecular breeding efforts across the family.

Application of biostimulants to improve tomato yield in Florida

Biostimulants are shown to increase crop production.This study was conducted to investigate the effects of individual biostimulants on tomato('Phoenix')growth and yield.Five biostimulants:CP_(1),CP_(2),BS,CP_(2)+BS,Competitor,and Water(control)were foliar applied at three different stages:pre-blooming,fruit setting,and color changing.The concentration of calcium(Ca),potassium(K),magnesium(Mg),and phosphorus(P)in leaves and roots were also determined.The results showed that plants treated with biostimulants had greater concentrations of Ca,K,Mg,and P compared to those treated with water only.Competitor and CP_(2)+BS significantly increased yield,plant height,and stem diameter by 76%and 41%,42%and 34%,and 29%and 24%.Likewise,leaf greenness,net photosynthetic rate(Pn),relative water content(RWC),nitrate level in petiole sap,and fruit quality(citric acid,malic acid,tartaric acid,soluble solid concentration,and fruit firmness)were also improved by Competitor.In addition,enzymatic activities of nitrate reductase(NR)and nitrite reductase(NiR)were significantly increased by biostimulants compared to the control.Statistically,Competitor and CP_(2)+BS showed the greatest augmentation in plant height,stem diameter,leaf greenness,PN,RWC,nitrate level in petiole sap,and fruit yield and quality.Similarly,Competitor-treated plants also increased NR,NiR,leaf Ca,leaf K,leaf Mg,and leaf P by 34%,70%,22%,26%,27%,and 45%,respectively.Based on the findings of this study,application of Competitor or CP2+BS showed promising results and may be used as a BMP tool for tomato production in Florida.

Genomics Approaches to Domestication Studies of Horticultural Crops

The majority of crops we eat today are derived from the domestication of their wild progenitors. Crop domestication satisfies the human need for food and nutrition. Characterization of the history and genetic basis of crop domestication is essential for us to conduct modern breeding practices. Genomics provide unprecedented opportunities for us to study domestication. In this review, the typical domestication syndromes of horticultural crops will be introduced. Using the tomato as a typical example, we will discuss how genetic and genomic data were used to decipher the origins, progenitors, and domestication processes of this crop. In the domestication exploration of the genetic basis especially,genome-scaled diversity scanning approaches have gained great popularity. Combining these approaches with QTL(Quantitative trait locus)-mapping, GWAS(Genome wide association study), metabolomics and homology-based searches as well as pan-genomics have demonstrated tremendous advantages and significantly contribute to our understanding of domestication. Genomics studies will accelerate domestication research and further breeding of crops.