White Fruit Color Research Articles

Genome-wide identification and analysis of anthocyanin synthesis-related R2R3-MYB genes in Fragaria pentaphylla

BackgroundMYB transcription factors regulate anthocyanin biosynthesis across numerous plant species. However, comprehensive genome-wide investigations regarding the R2R3-MYB gene family and its involvement in regulating anthocyanin biosynthesis in the red and white fruit color morphs of Fragaria pentaphylla remain scarce.ResultsA total of 101 FpR2R3-MYB genes were identified from the F. pentaphylla genome and were divided into 34 subgroups based on phylogenetic analysis. Gene structure (exon/intron) and protein motifs were particularly conserved among the FpR2R3-MYB genes, especially members within the same subgroup. The FpR2R3-MYB genes were distributed over seven F. pentaphylla chromosomes. Analysis of gene duplication events revealed five pairs of tandem duplication genes and 16 pairs of segmental duplication genes, suggesting that segmental duplications are the major pattern for expansion of the FpR2R3-MYB gene family expansion in F. pentaphylla. Cis-regulatory elements of the FpR2R3-MYB promoters were involved in cellular development, phytohormones, environmental stress and photoresponse. Based on the analysis of the FpR2R3-MYB gene family and transcriptome sequencing (RNA-seq) data, FpMYB9 was identified as a key transcription factor involved in the regulation of anthocyanin synthesis in F. pentaphylla fruits. The expression of FpMYB9 increases significantly during the ripening stage of red fruits, as confirmed by reverse transcription quantitative real-time PCR. In addition, subcellular localization experiments further confirmed the nuclear presence of FpMYB9, supporting its role as a transcription factor involved in anthocyanin biosynthesis.ConclusionOur results showed that the FpR2R3-MYB genes are highly conserved and play important roles in the anthocyanin biosynthesis in F. pentaphylla fruits. Our results also provide a compelling basis for further understanding of the regulatory mechanism underlying the role of FpMYB9 in anthocyanin formation in F. pentaphylla fruits.

Genetic mapping and molecular marker development for white flesh color in tomato.

Fruit color significantly influences the quality of horticultural crops, which affects phytochemical diversity and consumer preferences. Despite its importance, the genetic basis of the white-colored fruit in tomatoes remains poorly understood. In this study, we demonstrate that white-fleshed tomato varieties accumulate fewer carotenoids than yellow-fleshed varieties. We developed various segregating populations by hybridizing red, yellow, and white fruit tomato cultivars. Genetic analysis revealed that the white fruit color trait is controlled by a single gene that dominates both red and yellow fruits. Bulk segregant RNA sequencing provided a preliminary map of a 3.17 Mb region on chromosome 3 associated with the white color trait. Based on kompetitive allele-specific PCR (KASP) markers, we narrowed the candidate gene region to 819 kb. Within this region, we identified a 4906-bp sequence absence variation near Phytoene Synthase 1 (SlPSY1) specific to white-colored tomatoes. Genotyping of the progeny and natural populations using a single nucleotide polymorphism adjacent to this absence of variation confirmed its key role in white fruit formation. Collectively, our findings provide insights into white fruit trait formation in tomatoes, enabling tomato breeders to precisely introduce white fruit traits for commercial exploitation.

Mutation of CsARC6 affects fruit color and increases fruit nutrition in cucumber.

A mutation of CsARC6 not only causes white fruit color in cucumber, but also affects plant growth and fruit quality. Fruit color of cucumber is a very important agronomic trait, but most of the genes affecting cucumber white fruit color are still unknow, and no further studies were reported on the effect of cucumber fruit quality caused by white fruit color genes. Here, we obtained a white fruit mutant em41 in cucumber by EMS mutagenesis. The mutant gene was mapped to a 548kb region of chromosome 2. Through mutation site analysis, it was found to be a null allele of CsARC6 (CsaV3_2G029290). The Csarc6 mutant has a typical phenotype of arc6 mutant that mesophyll cells contained only one or two giant chloroplasts. ARC6 protein was not detected in em41, and the level of FtsZ1 and FtsZ2 was also reduced. In addition, FtsZ2 could not form FtsZ ring-like structures in em41. Although these are typical arc6 mutant phenotypes, some special phenotypes occur in Csarc6 mutant, such as dwarfness with shortened internodes, enlarged fruit epidermal cells, decreased carotenoid contents, smaller fruits, and increased fruit nutrient contents. This study discovered a new gene, CsARC6, which not only controls the white fruit color, but also affects plant growth and fruit quality in cucumber.

Chromosome-level genome assembly of Fragaria pentaphylla using PacBio and Hi-C technologies.

Fragaria pentaphylla, a wild diploid quinquefoliolate species of Fragaria, is native to Southwest China. It has two morphs of red and white fruit color in nature and has characteristics of unique fragrance and resistance, which made it not only a valuable breeding material but also a potential model plant for molecular function researches. Here, we generate a high-quality chromosome-level genome assembly of a F. pentaphylla accession, BAAFS-FP039 employing a combination of PacBio Long-Read Sequencing, Illumina Short-Read Sequencing, and Hi-C Sequencing. The assembled genome contained 256.74 Mb and a contig N50 length of 32.38 Mb, accounting for 99.9% of the estimated genome (256.77 Mb). Based on Hi-C data, seven pseudo-chromosomes of F. pentaphylla-FP039 genome were assembled, covering 99.39% of the genome assembly. The genome was composed of 44.61% repetitive sequences and 29,623 protein-coding genes, 97.62% of protein-coding genes could be functionally annotated. Phylogenetic and chromosome syntenic analysis revealed that F. pentaphylla-FP039 was closely related to F. nubicola. This high-quality genome could provides fundamental molecular resources for evolutionary studies, breeding efforts, and exploring the unique biological characteristics of F. pentaphylla.

Genetic diversity and offspring fitness in the red and white fruit color morphs of the wild strawberry Fragaria pentaphylla

Abstract Aims Fruit color polymorphisms are widespread in plants, but what maintains them is largely unclear. One hypothesis is that some morphs are preferred by dispersers while others have higher pre- or postdispersal fitness. This leads to the prediction that fruit color morphs will differ in pre- or postdispersal fitness. Methods We compared genetic and clonal diversity, mating system, morphological traits that might be associated with resistance to freezing, and germination, survival and seed production of progeny of the red and white fruit morphs in a population of a diploid, wild strawberry, Fragaria pentaphylla, from south-central China. Important Findings The red morph was much more abundant than the white but did not show higher genetic diversity as measured by observed and effective numbers of alleles, Shannon information index, or expected or observed heterozygosities. AMOVA showed that most of the genetic variation in the population was within rather than between morphs. Morphs did not differ in mating system parameters, and no significant biparental inbreeding was found in either morph. Gene flow between two morphs was high (Nm = 6.89). Seeds of the red morph germinated about 2 days earlier and had a 40% higher rate of germination than those of the white morph, but survival of seedlings and seed production by surviving offspring did not differ between morphs. The whole postdispersal fitness of the red morph was about two times higher than that of the white morph. Red morphs had hairier petioles but not more surface wax on leaves. Overall, results showed partial evidence for difference in pre- and postdispersal fitness between fruit color morphs in F. pentaphylla. Differences in fitness independent of dispersal may thus partially account for fruit color polymorphism in all cases.

RNA sequencing and anthocyanin synthesis-related genes expression analyses in white-fruited Vaccinium uliginosum

BackgroundVaccinium uliginosum (Ericaceae) is an important wild berry having high economic value. The white-fruited V. uliginosum variety found in the wild lacks anthocyanin and bears silvery white fruits. Hence, it is a good resource for investigating the mechanism of fruit color development. This study aimed to verify the differences in the expression levels of some structural genes and transcription factors affecting the anthocyanin biosynthesis pathway by conducting high-throughput transcriptome sequencing and real-time PCR analysis by using the ripening fruits of V. uliginosum and the white-fruited variety.ResultsWe annotated 42,837 unigenes. Of the 325 differentially expressed genes, 41 were up-regulated and 284 were down-regulated. Further, 11 structural genes of the flavonoid pathway were up-regulated, whereas two were down-regulated. Of the seven genes encoding transcription factors, five were up-regulated and two were down-regulated. The structural genes VuCHS, VuF3’H, VuFHT, VuDFR, VuANS, VuANR, and VuUFGT and the transcription factors VubHLH92, VuMYB6, VuMYBPA1, VuMYB11, and VuMYB12 were significantly down-regulated. However, the expression of only VuMYB6 and VuMYBPA1 rapidly increased during the last two stages of V. uliginosum when the fruit was ripening, consistent with anthocyanin accumulation.ConclusionsVuMYB6 was annotated as MYB1 by the BLAST tool. Thus, the white fruit color in the V. uliginosum variant can be attributed to the down-regulation of transcription factors VuMYB1 and VuMYBPA1, which leads to the down-regulation of structural genes associated with the anthocyanin synthesis pathway.

Genotyping of red and white fruited strawberry (Fragaria L.) accessions and hybrids based on microsatellite markers and on the genetic diversity in the allergen genes fra a 1 and fra a 3

Despite the beneficial nutritional value of strawberries, there is a potential risk of allergic reactions in consuming strawberries, especially for people with Bet v 1 allergy. Allergen content varies in the fruits depending on environmental and genetic backgrounds, also involving the fruit color. Diploid strawberry varieties on the European market, bearing white and red colored fruits (‘Blanc Ameliore’, ‘Weise Hagmann’, ‘Weise Solemacher’, ‘Yellow Wonder’, ‘Rote Baron Solemacher’, ‘Walderdbeere’) in addition to a new accession VM2012 were characterized by microsatellite analyses. Three strawberry varieties with white colored fruits, ‘Weise Hagmann’, ‘Weise Solemacher’, ‘Yellow Wonder’, were very similar to each other, but ‘Blanc Ameliore’ and VM2012 could be distinguished from the other varieties. The allergen genes fra a 1 and fra a 3 of diploid red and white colored strawberry varieties and VM2012 were identical on genomic level. Of the eight gene variants described for fra a 1 in octoploid strawberries (Fragaria × ananassa) only the gene variant fra a 1 A2 was highly conserved present in the diploid varieties of Fragaria vesca, indicating a role of F. vesca in the phylogeny of octoploid strawberries. For fra a 3, the sequence differed only in a single nucleotide exchange T503C from the octoploid sequence of the variety ‘Camarosa’, with no effect on the protein sequence. No complementation with regard to the fruit color was observed in crosses between VM2012 and the white colored diploid varieties ‘Weise Hagmann’ and ‘Weise Solemacher’ indicating that the genetic cause behind the white fruit color might be similar.

Inheritance of light pigmentation in squash

ABSTBACT: The Inheritance of light external fruit pigmentation of squash {Cucurttta pepo L.) was studied at two stages of growth: 2-5 days past anthesls (dpa) (young, edible summer squash stage) and 18-22 dpa (Intermediate stage of fruit development). Four cuitivars and their F,s and Fjs were studied: Early Prolific Stralghtneck (EPS), Slhl Lavan (= White Bush) (SLA), Bennlng's Green Tint (BGT), and Vegetable Spaghetti (VSP), all four of which are lightly pigmented 2-5 dpa and all except the first remain lightly pigmented throughout growth. The results Indicated that the four cuitivars carry the same gene (/) for light pigmentation at 2-5 dpa. Two of the four cuttlvars, SLA and VSP, also carry gene r that in concert with / determines light fruit pigmentation at 18-22 dpa. EPS and BGT carry R that conditions Intense fruit pigmentation at 1822 dpa. BGT is lightly pigmented at 18-22 dpa because It carries W (white fruit color), which Is epistatic to ft The genotypes of the four cuitivars are EPS, II RR wv^BCJ, II RR WW; and SLA and VSP, llrrww.

Studies of Grape Leafroll in California

Transmission experiments from Mission vines to Emperor indicators showed that Mission can Be infected with the grape leafroll virus. Foliar symptoms of leafroll are more distinct in Mission than in Emperor, and appear sooner following inoculation. Inoculation of mature red-fruited Emperor will produce fruit symptoms, or inoculation of Mission cuttings will produce leaf symptoms of the leafroll virus within 6 months. A white fruit color in varieties that normally produce red fruit, a premature reddening of leaves in varieties that produce red or black fruit, a downward rolling of the leaf margins, and an early burning of grape foliage were all shown by graft transmission tests to Emperor and Mission indicator vines fo be symptoms of grape leafroll. Surveys based on leafroll symptoms indicate that the incidence of leafroll may be 80 percent or more in many California vineyards, particularly wine-grape vineyards in the coastal counties, though not all California vineyards are so seriously affected and some are completely free of the disease. Indexing of a small sample of wine-grape varieties from coastal vineyards indicated that over half of the vines were infected with grape leafroll virus. Indexing of vines of grape rootstocks and grape varieties and selections growing on rootstocks obtained from experimental plantings at Davis and Oakville, California, showed that about 34 percent of the vines were infected with grape leafroll virus. Problems arising from leafroll virus infection and factors influencing the spread of leafroll are discussed.