Comparison of carotenoid,chlorophyll concentrations and their biosynthetic transcript levels in different coloured cauliflower

Carotenoids and chlorophylls are among the most widely distributed pigments in nature that play essential roles in the photosynthetic apparatus and confer diverse colours in plants.Among all vegetables,cauliflower(Brassica oleracea L.ssp.var.botrytis)is rich in phytochemicals and is an important crop grown all over the world.This study investigates carotenoid and chlorophyll concentrations in differently pigmented cultivars and elucidates the role of transcriptional regulation of carotenoid accumulation including lutein andβ-carotene.Here,we characterised changes in pigments by UHPLC-DAD-ToF-MS and changes in transcript levels of carotenoid metabolic genes by qRT-PCR in florets and leaves of orange(‘Jaffa'and‘Sunset'),purple(‘Di Sicilia Violetto'and‘Graffiti'),green(‘Trevi')and white(‘Clapton')cultivars.Transcript levels of all carotenoid metabolic genes showed different transcript level patterns in the leaves and florets.Compared to the other cultivars,the orange cultivars had the highest levels ofβ-carotene in the florets and lutein in the leaves resulting in changes lutein/β-carotene ratios.In the green cultivar,higher transcript levels were also found,especially for phytoene synthase and phytoene desaturase genes of the core biosynthesis pathway.However,no increased carotenoid concentrations were observed,possibly due to a higher carotenoid turnover induced by the carotenoid cleavage dioxygenase 4 in the green cultivar.In the white(‘Clapton')and purple(‘Di Sicilia Violetto'and‘Graffiti')cultivars the phytoene desaturase transcript levels as well as carotenoid concentrations were low.Chlorophyll concentrations changed in trend comparable to the carotenoid concentrations and were only significantly lower in the leaves of the orange cultivar‘Jaffa'.Also,the chlorophyll a/b ratio changed in‘Jaffa'.In florets the highest chlorophylls concentrations were observed for the green cultivar(‘Trevi')and the purple cultivar(‘Di Sicilia Violetto').Taken together,the study demonstrates the complex source-sink relationship of carotenoid accumulation in different coloured cauliflower.

Production of autotetraploid plants by in vitro chromosome engineering in Allium hirtifolium

Persian shallot has been propagated vegetatively through daughter bulbs and has a narrow genetic base.In the present study,to create genetic diversity in terms of ploidy level,the effects of in vitro polyploidization were investigated on morphological,physiological and phytochemical traits.Different colchicine treatments(0,0.3%,0.5% and 0.7% concentrations)for 24,36 and 48 h and oryzalin treatments(0,0.001%,0.002% and 0.004% concentrations)for 4,6 and 8 h were used.A sterile basal plate of bulbs was used for the induction of polyploidy in liquid and solid media.After obtaining plantlets,root tip chromosomes were counted for the determination of ploidy levels.Flow cytometry was performed to confirm the chromosome counting results.The regenerated diploid and tetraploid plantlets were transferred to ex vitro conditions.Colchicine and oryzalin were both successful in inducing polyploids and the polyploids induced were tetraploids and mixoploids.The highest induction of polyploidy was obtained in solid media using 0.5%(w/v)colchicine for 36 h(35.0% polyploidy induction)and in 0.001%(w/v)Oryzalin for 8 h(45.5% polyploidy induction).Differences in plantlet height and weight,bulblet weight,density,stomatal width and length,and chlorophyll content were observed between tetraploid and diploid plants.Chromosome duplication,as a result of tetraploid induction,significantly influenced the antioxidant content and enzyme activities.The results showed that total phenolic content,allicin,and antioxidant capacity were significantly higher in the tetraploid plantlets than that in the diploid plantlets.SRAP loci polymorphisms indicated that the 12 autotetraploid plants(with high allicin content)had different genotypes from the parental diploid plant.Besides,in vitro polyploidy induction not only duplicated chromosomes but also altered the DNA sequence in Allium hirtifolium.In vitro induction of tetraploids in A.hirtifolium can be a reliable way to obtain suitable plant material for breeding programs to generate new genotypic variations.

Gene editing of authentic Brassica rapa flavonol synthase 1 generates dihydroflavonol-accumulating Chinese cabbage

Flavonols are the major class of flavonoids of green Chinese cabbage(Brassica rapa subsp.pekinensis).The B.rapa genome harbors seven flavonol synthase genes(BrFLSs),but they have not been functionally characterized.Here,transcriptome analysis showed four BrFLSs mainly expressed in Chinese cabbage.Among them,only BrFLS1 showed major FLS activity and additional flavanone 3β-hydroxylase(F3H)activity,while BrFLS2 and BrFLS3.1 exhibited only marginal F3H activities.We generated BrFLS1-knockout(BrFLS1-KO)Chinese cabbages using CRISPR/Cas9-mediated genome editing and obtained transgene-free homozygous plants without off-target mutation in the T1 generation,which were further advanced to the T2 generation showing normal phenotype.UPLC-ESI-QTOF-MS analysis revealed that flavonol glycosides were dramatically decreased in the T2 plants,while dihydroflavonol glycosides accumulated concomitantly to levels corresponding to the reduced levels of flavonols.Quantitative PCR analysis revealed that the early steps of phenylpropanoid and flavonoid biosynthetic pathway were upregulated in the BrFLS1-KO plants.In accordance,total phenolic contents were slightly enhanced in the BrFLS1-KO plants,which suggests a negative role of flavonols in phenylpropanoid and flavonoid biosynthesis in Chinese cabbage.Phenotypic surveys revealed that the BrFLS1-KO Chinese cabbages showed normal head formation and reproductive phenotypes,but subtle morphological changes in their heads were observed.In addition,their seedlings were susceptible to osmotic stress compared to the controls,suggesting that flavonols play a positive role for osmotic stress tolerance in B.rapa seedling.In this study,we showed that CRISPR/Cas9-mediated BrFLS1-KO successfully generated a valuable breeding resource of Chinese cabbage with distinctive metabolic traits and that CRISPR/Cas9 can be efficiently applied in functional Chinese cabbage breeding.

Heterosis of Vine Decline Disease Resistance Caused by the Fungus Monosporascus cannonballus in Melons (Cucumis melo L)

Vine decline disease (VDD) constitutes a menace to melons worldwide. Especially, the one caused by the fungus Monosporascus cannonballus. Thus, resistant plant material must be released to help growers. Hence, our goal was to develop resistant plant material to VDD. More than 600 melon accessions are expected to be tested for disease resistance in M. cannonballus infested soil in Weslaco, Texas, USA, to identify resistance to VDD, and other important traits. So far, at most 7 lines were found to be resistant to VDD and some of them were used to develop elite, muskmelon inbred lines by pedigree breeding following single or double backcrosses. These elite parents were crossed to each other to develop the hybrids M3 and M4. They were also tested in the same infested field in Weslaco. The hybrids were grown using standard commercial practices followed by growers and when their fruits were ready, their roots were sampled as well as scored for disease severity to estimate high and mid-parent heterosis Our results indicate the existence of heterosis regarding resistance to VDD. Thus, resistant plant material can be developed and selection for resistance can be accomplished.

Responses of Soil Microbial Community Structure and Diversity to Agricultural Deintensification

Using a scheme of agricultural fields with progressively less intensive management (deintensification), different manage- ment practices in six agroecosystems located near Goldsboro, NC, USA were tested in a large-scale experiment, including two cash-grain cropping systems employing either tillage (CT) or no-tillage (NT), an organic farming system (OR), an integrated cropping system with animals (IN), a successional field (SU), and a plantation woodlot (WO). Microbial phos- pholipid fatty acid (PLFA) profiles and substrate utilization patterns (BIOLOG ECO plates) were measured to examine the effects of deintensification on the structure and diversity of soil microbial communities. Principle component analyses of PLFA and BIOLOG data showed that the microbial community structure diverged among the soils of the six systems. Lower microbial diversity was found in lowly managed ecosystem than that in intensive and moderately managed agro- ecosystems, and both fungal contribution to the total identified PLFAs and the ratio of microbial biomass C/N increased along with agricultural deintensification. Significantly higher ratios of C/N (P < 0.05) were found in the WO and SU systems, and for fungal/bacterial PLFAs in the WO system (P < 0.05). There were also significant decreases (P < 0.05) along with agricultural deintensification for contributions of total bacterial and gram positive (G+) bacterial PLFAs. Agricultural deintensification could facilitate the development of microbial communities that favor soil fungi over bacteria.

Effect of plant extracts on activity of some defense enzymes of apple fruit in interaction with Botrytis cinerea

The efficacy of seven plant extracts(neem,fennel,lavender,thyme,pennyroyal,salvia and asafetida) in controlling postharvest of apple(caused by Botrytis cinerea) was evaluated in vitro and in vivo.In vitro,all plant extracts treatments inhibited spore germination.Inhibitory rates of pore germination was 17.41 and 20.83% for neem extract treatment(methanolic and aqueous extracts,respectively) with significant difference compared to control(73.6 and 85.33%) for aqueous and methanol extracts.In the storage conditions,the application of aqueous extract of neem(at concentration of 25%) resulted in 89.11% reduction of disease severity compared with the untreated control.Results of enzymes activity showed the plant extracts can increase the activity of peroxidase,phenylalanine ammonia-lyase,β-1,3-glucanase and polyphenol oxidase in the presence of pathogens,in apple fruits.However,the results of this research revealed that application of neem extracts was more effective than the application of other plant extracts.According to this study,it could be concluded that plant extracts may be useful to control postharvest disease as a safe alternative option to chemical fungicides.

Overcoming seed dormancy of mooseer(Allium hirtifolium) through cold stratification,gibberellic acid,and acid scarification

Mooseer （Allium hirtifolium Boiss.） is bulbous perennial herb widely used in pharmaceutical and food industry in Iran. We studied germination of mooseer seeds in two separate experiments. In the first experiment, we evaluated four treatments： sulfuric acid scarification, sandpaper scarification, cold stratification, and gibberellic acid （GA3） application. In the second experiment, we evaluated combinations of these treatments. All treatments in the first experiment had no effect on seed germination, suggesting that mooseer seeds have physical and physiological dormancy. In the second experiment, the highest germina- tion percentage （86.6%） was observed after five minutes scarification with sulfuric acid （75% v/v）, followed by 60 days of cold stratification. Duration of sulfuric acid scarification （5, 10, and 20 min） did not affect germination rates, but increasing duration of cold stratification （from 15 to 60 days）, increased germination from 28.3% to 86.6%. Our study showed that mooseer seeds have both physical and physiological dormancy.

Cadmium and lead effects on chlorophyll fluorescence,chlorophyll pigments and proline of Robinia pseudoacacia

Heavy metal contamination is one of the most important abiotic stresses affecting physiological activities of plants.We investigated the effects of cadmium（Cd） and lead（Pb） on chlorophyll fluorescence（Fv/Fm,Fo,and Fm）,photosynthetic pigments（chlorophyll a and b）,and proline in one-year-old seedlings of Robinia pseudoacacia.The seedlings were treated twice over a period of 10 days with Cd and Pb at concentrations of 0,250,500,1000 and2000 mg L-1.Saline solution containing Cd and Pb was sprayed on the leaves.Chlorophyll and proline contents were measured after 10 days.Chlorophyll fluorescence of R.pseudoacacia was affected slightly by high concentrations（1000,2000 mg L-1） of Cd and Pb.Chlorophyll a and a/b increased at 1000 and 2000 mg L-1of Cd and proline content of leaves was similar in all treatments of Cd and Pb.Our results indicated that photosynthetic sensitivity of R.pseudoacacia to Cd and Pb contamination was weak.Photosystem II chlorophyll pigments were not damaged by Pb and Cd stress.We conclude that chlorophyll fluorescence along with chlorophyll and proline contents are useful indicators of Cd and Pb stresses in R.pseudoacacia which widely planted in urban polluted regions in Iran.

Elucidation of the ‘Honeycrisp’ pedigree through haplotype analysis with a multi-family integrated SNP linkage map and a large apple (Malus×domestica) pedigree-connected SNP data set

The apple(Malus×domestica)cultivar Honeycrisp has become important economically and as a breeding parent.An earlier study with SSR markers indicated the original recorded pedigree of‘Honeycrisp’was incorrect and‘Keepsake’was identified as one putative parent,the other being unknown.The objective of this study was to verify‘Keepsake’as a parent and identify and genetically describe the unknown parent and its grandparents.A multi-family based dense and high-quality integrated SNP map was created using the apple 8 K Illumina Infinium SNP array.This map was used alongside a large pedigree-connected data set from the RosBREED project to build extended SNP haplotypes and to identify pedigree relationships.‘Keepsake’was verified as one parent of‘Honeycrisp’and‘Duchess of Oldenburg’and‘Golden Delicious’were identified as grandparents through the unknown parent.Following this finding,siblings of‘Honeycrisp’were identified using the SNP data.Breeding records from several of these siblings suggested that the previously unreported parent is a University of Minnesota selection,MN1627.This selection is no longer available,but now is genetically described through imputed SNP haplotypes.We also present the mosaic grandparental composition of‘Honeycrisp’for each of its 17 chromosome pairs.This new pedigree and genetic information will be useful in future pedigree-based genetic studies to connect‘Honeycrisp’with other cultivars used widely in apple breeding programs.The created SNP linkage map will benefit future research using the data from the Illumina apple 8 and 20 K and Affymetrix 480 K SNP arrays.

Harvest and Postharvest Factors Affecting Bruise Damage of Fresh Fruits

Fresh fruits are susceptible to bruising, a common type of mechanical damage during harvest and at all stages of postharvest handling. In quest of developing and adoption of strategies to reduce bruise damage, it is of utmost importance to understand major factors influencing bruise susceptibility of fresh produce at these stages. This review presents a critical discussion of factors affecting bruising during harvest and postharvest handling of fresh fruits. Excessive compression forces during harvesting by handpicking or machines, and a series of impacts during harvesting, transport and packhouse operations can cause severe bruise damage. The review has further revealed that bruising is dependent on a number of other factors such as produce maturity, ripening, harvest time(during the day or season) and time lapse after harvest. The susceptibility to bruising is partly dependent on how these factors alter the produce physiological and biochemical properties, and the environmental conditions such as temperature, humidity and several other postharvest treatments. Hence, the successful applications of harvesting techniques by use of trained personnel and proper harvesting equipment are essential to reduce both the incidence and severity of bruising.Furthermore, the careful selection of postharvest handling temperature and other treatments can increase resistance of fresh produce to bruise damage.

The Role of Cover Crops towards Sustainable Soil Health and Agriculture—A Review Paper

Cover crops are the plants which are grown to improve soil fertility, prevent soil erosion, enrichment and protection of soil, and enhance nutrient and water availability, and quality of soil. Cover crops provide several benefits to soils used for agriculture production. Cover crops are helpful in increasing and sustaining microbial biodiversity in soils. We summarized the effect of several cover crops in soil properties such as soil moisture content, soil microbial activities, soil carbon sequestration, nitrate leaching, soil water, and soil health. Selection of cover crops usually depends on the primary benefits which are provided by cover crops. Other factors may also include weather conditions, time of sowing, either legume or non-legume and timing and method of killing of a cover crop. In recent times, cover crops are also used for mitigating climate change, suppressing weeds in crops and increasing exchangeable nutrients such as Mg2+ and K+. Cover crops are also found to be economical in long-term experiment studies. Although some limitations always come with several benefits. Cover crops have some problems including the method of killing, host for pathogens, regeneration, and not immediate benefits of using them. Despite the few limitations, cover crops improve the overall health of the soil and provide a sustainable environment for the main crops.

Differential response of tomato genotypes to Xanthomonas-specific pathogen-associated molecular patterns and correlation with bacterial spot (Xanthomonas perforans) resistance

Plants depend on innate immune responses to retard the initial spread of pathogens entering through stomata,hydathodes or injuries.These responses are triggered by conserved patterns in pathogen-encoded molecules known as pathogen-associated molecular patterns(PAMPs).Production of reactive oxygen species(ROS)is one of the first responses,and the resulting‘oxidative burst’is considered to be a first line of defense.In this study,we conducted association analyses between ROS production and bacterial spot(BS;Xanthomonas spp.)resistance in 63 genotypes of tomato(Solanum lycopersicum L.).A luminol-based assay was performed on leaf tissues that had been treated with a flagellin 22(flg22),flagellin 28 and a Xanthomonas-specific flg22(flg22-Xac)peptide,to measure PAMP-induced ROS production in each genotype.These genotypes were also assessed for BS disease response by inoculation with Xanthomonas perforans,race T4.Although there was no consistent relationship between peptides used and host response to the BS,there was a significant negative correlation(r=−0.25,P<0.05)between foliar disease severity and ROS production,when flg22-Xac was used.This response could potentially be used to identify the Xanthomonas-specific PRR allele in tomato,and eventually PAMP-triggered immunity loci could be mapped in a segregating population.This has potential significance in tomato improvement.

Iran supports a great share of biodiversity and floristic endemism for Fritillaria spp.(Liliaceae)：A review

Iran supports a great share of exotic and/or endemic plant genera and species. The genus Fritillaria(Liliaceae) is a precious part of this botanical richness with 19 species, of which 10 are endemic to the country. However, signs are mounting that the country is truly at a crossroads when it comes to preservation of this national wealth. In this regard, an effective conservation strategy should thoroughly consider the classification of Fritillaria, as conservation practices are compromised by knowledge gaps in systematics and taxonomy. As published studies on Fritillaria in Iran have been sporadic and limited in scope, the aim of this review is to provide information necessary to help bridge these information gaps.Our objective is to facilitate increased understanding of the geographic, taxonomic, cytogenetic and phylogenetic status of Iranian Fritilloria, which is vital to meeting the goal of sustainable conservation of the genus in Iran and neighboring areas.

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.

Fermentation of mulberry leaves with Cordyceps militaris enhanced anti-adipogenesis activity in 3T3-L1 cells through down-regulation of PPAR-γ pathway signaling

Objective:To establish an efficacious and efficient fermentation method of enhancing the anti-adipogenesis effect of mulberry(Morus alba) leaves using Cordyceps militais.Methods:Dried mulberry leaves,dried mulberry leaves with50% raw silkworm pupa and raw silkworm pupa were fermented with Cordyceps militais for 4 weeks at 25℃,after which the dried mulberry leaves and fermented product were extracted with 70%ethanol and subjected to high performance liquid chromatography(HPLC).The contents of cordycepin,pelargonidin,chlorogenic acid,iso-quercetin and caffeic acid were determined.We then used the 3 T3-L1 cells to investigate whether extracts of fermentation enhanced anti-adipogenesis activity in vitro.Results:HPLC showed that fermentation changed the contents of cordycepin,pelargonidin,chlorogenic acid,iso-quercetin and caffeic acid.Furthermore,fermented dried mulberry leaves with 50% raw silkworm pupa had a better efficacy of anti-adipogenesis than dried mulberry leaves,fermented dried mulberry leaves and fermented silkworm pupa and inhibited triglycerides accumulation and glucose consumption.Additionally,fermented dried mulberry leaves with50% raw silkworm pupa inhibited PPAR-γ signaling.Conclusions:Fermentation with Cordyceps militaris enhanced antiadipogenesis efficacy of mulberry leaves.

Inheritance and allelism of morphological traits in eastern redbud (Cercis canadensis L.)

Inheritance of purple,gold,and variegated foliage types,weeping architecture,and double flower was explored in F1,F2,and backcross families resulting from controlled hybridization of eastern redbud(Cercis canadensis L.).Potential allelic relationships were explored when possible.Inheritance analysis in families derived from controlled hybridization of‘Covey’(green leaf)and‘Forest Pansy’(purple leaf)suggest that purple leaf color and weeping architecture are both controlled by single recessive genes,for which the symbols pl1 and wp1 are proposed,respectively.Inheritance of gold leaf was explored in families of‘Covey’(green leaf)בHearts of Gold’(gold leaf).Interpretation of inheritance of gold leaf in these families was confounded by the recovery of a leaf color phenotype in the F2 family unlike either parent.However,data suggested the action of a single locus controlling gold leaf color in‘Hearts of Gold’,and that instability of gold leaf expression may be based on transposable element activity.Segregation of gold leaf in the F2 families of‘Texas White’[green leaf(C.canadensis var.texensis)]בJN2’[gold leaf(The Rising Sun)]did not fit a Mendelian ratio.Analysis of progeny of‘Silver Cloud’and‘Floating Clouds’(both showing white/green leaf variegation)with non-variegated cultivars demonstrated that variegation in‘Silver Cloud’is controlled by a single recessive nuclear gene,while variegation in‘Floating Clouds’is controlled by cytoplasmic factors.The symbol var1 is proposed for the gene controlling variegation in‘Silver Cloud’.Double flower in progeny derived from‘Flame’(double flower)suggested that double flower is dominant to single flower,and that‘Flame’is heterozygous at the double-flower locus,for which the symbol Df1 is proposed.Allelism studies showed that the gene controlling purple leaf in‘Forest Pansy’is allelic to the purple leaf gene in‘Greswan’and that the gene controlling weeping phenotype in‘Traveller’(C.canadensis var.texensis)is non-allelic to the weeping gene found in‘Covey’.Allelism of the gold leaf trait in‘Hearts of Gold’and‘JN2’was investigated,but no clear conclusions regarding allelism could be made due to recovery of leaf color phenotypes unlike either parent.

Effect of post-harvest UV-C irradiation and calcium chloride on enzymatic activity and decay of tomato(Lycopersicon esculentum L.)fruit during storage

Tomato is one of the extensively consumed vegetable crops worldwide. The regular consumption of tomato decreases the incidence of chronic degenerative diseases such as certain types of cancer and cardiovascular diseases. The objective of this study was to find an appropriate method that not only reduces tomatoes decay, but also maintains its post-harvest quality. A factorial experiment based on randomized complete block design with three replications was conducted to evaluate effects of ultraviolet（UV）-C and CaCl_2 applications on tomato during storage. The traits studied included ethylene, polygalacturonase（PG） activity, pectin methyl esterase（PME） activity, firmness, total phenol content, and fungal-induced decay were measured weekly during 35 days of storage. Both UV-C and CaCl_2 treatments had positive effects on tomato quality as compared to control treatment. The 3 and 4.5 k J m^（-2） levels of UV-C and 2% CaCl_2 had positive effects on quality characteristics, respectivly. Fruits treated by UV-C and CaCl_2 had higher phenol and firmness, and less PME activity, PG activity, ethylene production, and decay than the control fruits. In conclusion, increasing in storage duration significantly affected the fruits quality by increasing in ethylene, PME activity, PG activity, decay and decreasing the phenol content and firmness. But UV-C and CaCl_2 led to significant decrease in this adverse impact relative to control treatment.

High-density linkage map construction and identification of loci regulating fruit quality traits in blueberry

Fruit quality traits play a significant role in consumer preferences and consumption in blueberry(Vaccinium corymbosum L).The objectives of this study were to construct a high-density linkage map and to identify the underlying genetic basis of fruit quality traits in blueberry.A total of 287 F_(1) individuals derived from a cross between two southern highbush blueberry cultivars,‘Reveille’and‘Arlen’,were phenotyped over three years(2016–2018)for fruit quality-related traits,including titratable acidity,pH,total soluble solids,and fruit weight.A high-density linkage map was constructed using 17k single nucleotide polymorphisms markers.The linkage map spanned a total of 1397 cM with an average inter-loci distance of 0.08 cM.The quantitative trait loci interval mapping based on the hidden Markov model identified 18 loci for fruit quality traits,including seven loci for fruit weight,three loci for titratable acidity,five loci for pH,and three loci for total soluble solids.Ten of these loci were detected in more than one year.These loci explained phenotypic variance ranging from 7 to 28% for titratable acidity and total soluble solid,and 8-13% for pH.However,the loci identified for fruit weight did not explain more than 10%of the phenotypic variance.We also reported the association between fruit quality traits and metabolites detected by Proton nuclear magnetic resonance analysis directly responsible for these fruit quality traits.Organic acids,citric acid,and quinic acid were significantly(P<0.05)and positively correlated with titratable acidity.Sugar molecules showed a strong and positive correlation with total soluble solids.Overall,the study dissected the genetic basis of fruit quality traits and established an association between these fruit quality traits and metabolites.

Evolution of the MLO gene families in octoploid strawberry(Fragaria×ananassa)and progenitor diploid species identified potential genes for strawberry powdery mildew resistance

Powdery mildew(PM)caused by Podosphaera aphanis is a major fungal disease of cultivated strawberry.Mildew Resistance Locus O(MLO)is a gene family described for having conserved seven-transmembrane domains.Induced loss-of-function in specific MLO genes can confer durable and broad resistance against PM pathogens.However,the genomic structure and potential role of MLO genes for PM resistance have not been characterized yet in the octoploid cultivated strawberry.In the present study,MLO gene families were characterized in four diploid progenitor species(Fragaria vesca,F.iinumae,F.viridis,and F.nipponica)and octoploid cultivated(Fragaria×ananassa)strawberry,and potential sources of MLO-mediated susceptibility were identified.Twenty MLO sequences were identified in F.vesca and 68 identified in F.×ananassa.Phylogenetic analysis divided diploid and octoploid strawberry MLO genes into eight different clades,in which three FveMLO(MLO10,MLO17,and MLO20)and their twelve orthologs of FaMLO were grouped together with functionally characterized MLO genes conferring PM susceptibility.Copy number variations revealed differences in MLO composition among homoeologous chromosomes,supporting the distinct origin of each subgenome during the evolution of octoploid strawberry.Dissecting genomic sequence and structural variations in candidate FaMLO genes revealed their potential role associated with genetic controls and functionality in strawberry against PM pathogen.Furthermore,the gene expression profiling and RNAi silencing of putative FaMLO genes in response to the pathogen indicate the function in PM resistance.These results are a critical first step in understanding the function of strawberry MLO genes and will facilitate further genetic studies of PM resistance in cultivated strawberry.

Genome-wide SNP discovery and core marker sets for assessment of genetic variations in cultivated pumpkin(Cucurbita spp.)

Three pumpkin species Cucurbita maxima,C.moschata,and C.pepo are commonly cultivated worldwide.To identify genome-wide SNPs in these cultivated pumpkin species,we collected 48 F1 cultivars consisting of 40 intraspecific hybrids(15 C.maxima,18 C.moschata,and 7 C.pepo)and 8 interspecific hybrids(C.maxima x C.moschata).Genotyping by sequencing identified a total of 37,869 confident SNPs in this collection.These SNPs were filtered to generate a subset of 400 SNPs based on polymorphism and genome distribution.Of the 400 SNPs,288 were used to genotype an additional 188 accessions(94 F1 cultivars,50 breeding lines,and 44 landraces)with a SNP array-based platform.Reliable polymorphisms were observed in 224 SNPs(78.0%)and were used to assess genetic variations between and within the four predefined populations in 223 cultivated pumpkin accessions.Both principal component analysis and UPGMA clustering found four major clusters representing three pumpkin species and interspecific hybrids.This genetic differentiation was supported by pairwise Fst and Nei’s genetic distance.The interspecific hybrids showed a higher level of genetic diversity relative to the other three populations.Of the 224 SNPs,five subsets of 192,96,48,24,and 12 markers were evaluated for variety identification.The 192,96,and 48 marker sets identified 204(91.5%),190(85.2%),and 141(63.2%)of the 223 accessions,respectively,while other subsets showed<25%of variety identification rates.These SNP markers provide a molecular tool with many applications for genetics and breeding in cultivated pumpkin.