Yellow Petals Research Articles

The endemic plant species of Ebo Forest, Littoral Region, Cameroon, with a new Critically Endangered cloud forest shrub, Memecylon ebo (Melastomataceae-Olisbeoideae)

SummaryWe emphasise the urgent need to conserve the Ebo forest (Littoral Region, Cameroon), which holds 10 strict endemic plant species and 15 near endemics for a total of 25, a very high number far exceeding the threshold for its recent status as an Important Plant Area (IPA). We describe a further strict endemic species from the Ebo Forest, Memecylon ebo sp. nov. (Melastomataceae-Olisbeoideae), placed in sect. Afzeliana due to its ellipsoid, blue-green fruits. The yellow petals and jade green anther-connectives of M. ebo are unique in the genus Memecylon, which has >400 species ranging overall from Africa to the western Pacific. Memecylon ebo is assessed as Critically Endangered [CR], using the 2012 IUCN standard, due to its small range size and the extremely high and ongoing threats of logging at Ebo and also due to subsequent threats of potential oil palm plantation and mining projects. With the addition of Memecylon ebo, the tally of Critically Endangered plant species recorded from Ebo forest is now the highest of any IPA in Cameroon, equalling that of Ngovayang with 24 CR species.

Cover Image

Left: Natural habitat of the wild cotton Gossypium turneri in the coast of San Carlos, Sonora, Mexico. Right: Flower of Gossypium turneri in San Carlos, Sonora, Mexico. Flowering follows the rainy season in Sonora and the flowers are hermaphrodite with yellow petals and red spots near the base.Photos by Karla Fabiola Yescas‐Romo. Photos are courtesy of the authors of the article: Yescas‐Romo, K. F., Hayano‐Kanashiro, C., & Molina‐Freaner, F. (2024). Pollination biology of Gossypium turneri: Autonomous selfing provides reproductive assurance in an endangered wild cotton from Sonora, Mexico. Plant Species Biology, 39(5), 260–274. https://doi.org/10.1111/1442-1984.12474image

Integrative Metabolomic and Transcriptomic Analyses Reveal the Mechanism of Petal Blotch Formation in Rosa persica.

Petal blotch is a specific flower color pattern commonly found in angiosperm families. In particular, Rosa persica is characterized by dark red blotches at the base of yellow petals. Modern rose cultivars with blotches inherited the blotch trait from R. persica. Therefore, understanding the mechanism for blotch formation is crucial for breeding rose cultivars with various color patterns. In this study, the metabolites and genes responsible for the blotch formation in R. persica were identified for the first time through metabolomic and transcriptomic analyses using LC-MS/MS and RNA-seq. A total of 157 flavonoids were identified, with 7 anthocyanins as the major flavonoids, namely, cyanidin 3-O-(6″-O-malonyl) glucoside 5-O-glucoside, cyanidin-3-O-glucoside, cyanidin 3-O-galactoside, cyanidin O-rutinoside-O-malonylglucoside, pelargonidin 3-O-glucoside, pelargonidin 3,5-O-diglucoside, and peonidin O-rutinoside-O-malonylglucoside, contributing to pigmentation and color darkening in the blotch parts of R. persica, whereas carotenoids predominantly influenced the color formation of non-blotch parts. Zeaxanthin and antheraxanthin mainly contributed to the yellow color formation of petals at the semi-open and full bloom stages. The expression levels of two 4-coumarate: CoA ligase genes (Rbe014123 and Rbe028518), the dihydroflavonol 4-reductase gene (Rbe013916), the anthocyanidin synthase gene (Rbe016466), and UDP-flavonoid glucosyltransferase gene (Rbe026328) indicated that they might be the key structural genes affecting the formation and color of petal blotch. Correlation analysis combined with weighted gene co-expression network analysis (WGCNA) further characterized 10 transcription factors (TFs). These TFs might participate in the regulation of anthocyanin accumulation in the blotch parts of petals by modulating one or more structural genes. Our results elucidate the compounds and molecular mechanisms underlying petal blotch formation in R. persica and provide valuable candidate genes for the future genetic improvement of rose cultivars with novel flower color patterns.

Astragalus nallihanicus (sect. Caprini, Fabaceae), a new species from Türkiye

Some interesting Astragalus L. (Fabaceae) specimens that have short stems, long stipules and short yellow petals were collected from Nallıhan, Ankara. In the careful examination made, it was seen that the specimens resemble Astragalus ovinus Boiss., A. fabaceus M.Bieb. and A. angustiflorus K.Koch belonging to the section Caprini, but it was determined that there is a difference due especially to some generative characters. After comparison with the closest taxa, it was decided that it is new for science and was named Astragalus nallihanicus. It grows at altitudes between about 850-1050 meters a.s.l. in a pine forest clearing. The size of some morphological features such as stipules (lower ones 17-22 mm long), calyx teeth (8-9 mm long), standards (19-22 mm long), wings (16-18 mm long), legumes (8.3-10.5 mm wide) and the dimensions of the seeds (3.5-4.1 x 2.1-2.5 mm), allow Astragalus nallihanicus to be distinguished from the closest taxa. Here, a description of the new species, comparison with similar taxa, informative photographs, and some ecological preferences have been given.

Cuphea vazquezii (Lythraceae), a yellow-flowered new species from the Cerro Grande, Sierra de Manantlán, Colima, Mexico

Cuphea vazquezii (subgen. Cuphea, sect. Archocuphea, Lythraceae), a minute new species from Cerro Grande, Comala, Colima, Mexico, is described and illustrated. It is morphologically similar to C. mimuloides, from which it differs in having a none-rhizomatous habit; mostly alternate leaves and flowers; larger leaf blades; shorter pedicels; spurred floral tubes; two yellow petals; deflexed nectariferous disc; and larger seeds. According to IUCN criteria, the species was assessed as critically endangered (CR).

Comparative analysis of chloroplast genome and evolutionary history of Hemerocallis.

Members of the genus Hemerocallis have significant value as ornamental, edible, and medicinal plants, particularly in China, where they have been utilized for thousands of years as both a vegetable and Traditional Chinese Medicine. Hemerocallis species exhibit strict control over flowering time, with individuals flowering either diurnally or nocturnally. However, our understanding of the evolutionary history of this genus, especially concerning important horticultural traits, remains limited. In this study, sequencing and assembly efforts were conducted on 73 samples within the Hemerocallis genus. All accessions were classified into two distinct groups based on their diurnal (daylilies) or nocturnal (nightlilies) flowering habits. Comparative analysis of the chloroplast genomes from these two groups identified fifteen variant hotspot regions, including fourteen SNPs and one deletion, which hold promise for the development of molecular markers for interspecific identification. Phylogenetic trees, generated through both maximum-likelihood and Bayesian inference methods using 76 shared protein-coding sequences, revealed that diurnal flowering evolved prior to nocturnal flowering. The divergence between the two groups is estimated to have occurred approximately 0.82 MYA (95% CI: 0.35-1.45 MYA). The ancestral state of Hemerocallis is hypothesized to have featured diurnal flowering with orange yellow petals. This study marks the first reconstruction of the evolutionary history and ancestral state of the genus Hemerocallis. The findings contribute significantly to our understanding of the adaptation and speciation history within the genus.

<i>CAMELLIA HOABINHENSIS</i> (THEACEAE: SECT. <i>CHRYSANTHA</i>), A NEW YELLOW-FLOWERED SPECIES FROM NORTHERN VIETNAM

A new species, Camellia hoabinhensis (section Chrysantha, Theaceae), is described and illustrated based on specimens collected from a lowland forest on limestone hills in Hoa Binh Province, northern Vietnam. The species is characterized by its small habit to 4.5 m tall, large flowers 9.0–9.5 cm in diameter with 18–19 light yellow petals, and hairy filaments, ovaries, and styles. A comparison of the new species with similar species, C. euphlebia, C. impressinervis, C. phanii, and C. velutina, is provided. The IUCN conservation status of the proposed species is Data Deficient (DD).

Stigma receptivity and flower development stage during emasculation in tomato affect artificial hybridization

ABSTRACT Determination of appropriate stages of flower emasculation and flower development when self-pollination occurs in tomato (Solanum lycopersicum L.) flowers is important to increase the degree of success of cross pollination. The experiment was conducted from July 2015 to June 2017. Seven tomato varieties (as female parents) and 1 genotype (as pollen source) were evaluated. Stages of flower emasculation (3 levels) were: 1) emasculation of immature flowers (light yellow petal) (Stage I); 2) emasculation of mature flowers (dark yellow petal, and/or petal not opened) (Stage II); and 3) emasculation of mature flowers (dark yellow petal, and/or petal partially opened) (Stage III). Complete success of cross fertilization was for the interaction of Stage II (dark yellow petal, and/or petal not opened) flower emasculation with pollination of emasculated flower after 24 h. The lowest (1.8%) percent of success of cross fertilization was at stage I (light yellow petal) flower emasculation with pollination of emasculated flower within 12 h. The low range, 1.8–5.3% of success of cross fertilization was at flower stage III (dark yellow petal, and/or petal partially opened) emasculation with no pollination of emasculated flower, indicating occurrence of an accidental self-fertilization. Stage of flower development stage I (light yellow petal) and pollination of emasculated flowers after 48 h could give the optimum percent of success of cross fertilization and avoid accidental self-pollination.

Metabolome and Transcriptome Analyses Reveal Flower Color Differentiation Mechanisms in Various Sophora japonica L. Petal Types.

Sophora japonica L. is an important landscaping and ornamental tree species throughout southern and northern parts of China. The most common color of S. japonica petals is yellow and white. In this study, S. japonica flower color mutants with yellow and white flag petals and light purple-red wing and keel petals were used for transcriptomics and metabolomics analyses. To investigate the underlying mechanisms of flower color variation in S. japonica 'AM' mutant, 36 anthocyanin metabolites were screened in the anthocyanin-targeting metabolome. The results demonstrated that cyanidins such as cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside in the 'AM' mutant were the key metabolites responsible for the red color of the wing and keel petals. Transcriptome sequencing and differentially expressed gene (DEG) analysis identified the key structural genes and transcription factors related to anthocyanin biosynthesis. Among these, F3'5'H, ANS, UFGT79B1, bHLH, and WRKY expression was significantly correlated with the cyanidin-type anthocyanins (key regulatory factors affecting anthocyanin biosynthesis) in the flag, wing, and keel petals in S. japonica at various flower development stages.

Phylogeny of PmCCD Gene Family and Expression Analysis of Flower Coloration and Stress Response in Prunus mume.

The CCD gene family plays a crucial role in the cleavage of carotenoids, converting them into apocarotenoids. This process not only impacts the physiology and development of plants but also enhances their tolerance toward different stresses. However, the character of the PmCCD gene family and its role in ornamental woody Prunus mume remain unclear. Here, ten non-redundant PmCCD genes were identified from the P. mume genome, and their physicochemical characteristics were predicted. According to the phylogenetic tree, PmCCD proteins were classified into six subfamilies: CCD1, CCD4, CCD7, CCD8, NCED and CCD-like. The same subfamily possessed similar gene structural patterns and numbers of conserved motifs. Ten PmCCD genes were concentrated on three chromosomes. PmCCD genes exhibited interspecific collinearity with P. armeniaca and P. persica. Additionally, PmCCD genes had obvious specificity in different tissues and varieties. Compared with white-flowered 'ZLE', PmCCD1 and PmCCD4 genes were low-expressed in 'HJH' with yellow petals, which suggested PmCCD1 and PmCCD4 might be related to the formation of yellow flowers in P. mume. Nine PmCCD genes could respond to NaCl or PEG treatments. These genes might play a crucial role in salt and drought resistance in P. mume. Moreover, PmVAR3 and PmSAT3/5 interacted with PmCCD4 protein in yeast and tobacco leaf cells. This study laid a foundation for exploring the role of the PmCCD gene family in flower coloration and stress response in P. mume.

Unraveling Seasonal Allocation of Soluble Sugars, Starch and Proline in Sternbergia lutea.

This study focuses on Sternbergia lutea (L.) Ker Gawl. ex Spreng., a bulbous, perennial, autumnal flowering geophyte mainly distributed around the Mediterranean Basin. The seasonal content of total sugars, starch and proline in above- and below-ground plant parts in this study, which has hitherto not been the subject of a published study. Geophytes possess underground storage organs that support sprouting, leaf growth and flowering. Furthermore, their buds remain protected below the soil surface during periods of dormancy. Understanding the fluctuation of these compounds in S. lutea contributes to our knowledge of its adaptation to the Mediterranean ecosystem. It seems likely that monthly fluctuations in proline accumulation, sugar and starch content in both above- and below-ground tissues of S. lutea correspond to the distinct seasonality of the Mediterranean ecosystem. Elevated starch content was investigated in the bulbs, while lower starch content was estimated in the leaves. Substantial values of soluble sugar content have been detected in bulbs and leaves. Additionally, elevated sugar content was detected in the yellow petals of S. lutea in October. Pronounced proline accumulation was detected in the leaves and bulbs of S. lutea during its active and dormant phase, respectively.

Chromosome-scale genome assembly provides insights into flower coloration mechanisms of Canna indica

Canna indica, which produce conspicuous and colorful flowers, are widely appreciated as ornamental plants. We used Pacific Biosciences sequencing (PacBio) and chromosome conformation capture (Hi-C) genome scaffolding to build a high-quality chromosome-scale genome assembly of C. indica and the genome assembly was 821Mb with a contig N50 of 48Mb assembled into nine chromosomes. The genome of C. indica was predicted to contain 31,130 genes and 30,816 genes were functionally annotated. Genome annotation identified 522 Mb (63.59 %) as repetitive sequences. Genome evolution analysis showed that whole-genome duplication occurred 53.4 million years ago. Transcriptome analysis revealed that petal coloration was linked with the expression of genes encoding enzymes involved in anthocyanin biosynthesis, carotenoid biosynthesis, and the methylerythritol phosphate (MEP) pathway. Furthermore, modules of co-expressed genes and hub genes were identified via weighted gene co-expression network analysis. These results suggested that, in Canna indica, deep red petal coloration was regulated by CHS2 and yellow petal coloration was associated with expression of ARF6 and NAC14. Considered together, the current study revealed a high-quality reference genome which may provide new insights into the molecular basis of flower coloration in Canna indica and help enhance the conservation and breeding of ornamental plants in general.

Characterization Variation of the Differential Coloring Substances in Rapeseed Petals with Different Colors Using UPLC-HESI-MS/MS.

Rapeseed's (Brassica napus L.) colorful petals have important ornamental values. However, the mechanisms of regulating petals coloration in rapeseed are still unknown. In our study, we investigated the key differential coloring substances in nine rapeseed cultivars with different petal colors, and 543 metabolites were detected and characterized through UPLC-HESI-MS/MS. Among them, the kinds and contents of flavonols, flavones, and anthocyanidins were the main contributors to petals' coloration. Tamarixetin-, quercetin-, butin-, naringenin- and luteolin-derivates were the main pigment bases in white and yellow petals. Peonidin-3,5-O-diglucoside, peonidin-3-O-(6″-O-caffeoyl)glucoside, and quercetin-derivatives were the main coloring substances in pink petals. Acylated cyanidin derivatives might lead to a series of different purple petal colors. Glycosylated anthocyanins were responsible for the coloration of rapeseed red petals, and peonidin-3-O-glucoside and kaempferol-derivatives were mainly detected from the red petals. These results provide comprehensive insights into the difference in flavonoid metabolites in rapeseed petals with different colors and supply theoretical supports for the breeding of novel colorful rapeseed cultivars.

The R2R3-MYB transcription factor GaPC controls petal coloration in cotton

Although a few cases of genetic epistasis in plants have been reported, the combined analysis of genetically phenotypic segregation and the related molecular mechanism remains rarely studied. Here, we have identified a gene (named GaPC) controlling petal coloration in Gossypium arboreum and following a heritable recessive epistatic genetic model. Petal coloration is controlled by a single dominant gene, GaPC. A loss-of-function mutation of GaPC leads to a recessive gene Gapc that masks the phenotype of other color genes and shows recessive epistatic interactions. Map-based cloning showed that GaPC encodes an R2R3-MYB transcription factor. A 4814-bp long terminal repeat retrotransposon insertion at the second exon led to GaPC loss of function and disabled petal coloration. GaPC controlled petal coloration by regulating the anthocyanin and flavone biosynthesis pathways. Expression of core genes in the phenylpropanoid and anthocyanin pathways was higher in colored than in white petals. Petal color was conferred by flavonoids and anthocyanins, with red and yellow petals rich in anthocyanin and flavonol glycosides, respectively. This study provides new insight on molecular mechanism of recessive epistasis, also has potential breeding value by engineering GaPC to develop colored petals or fibers for multi-functional utilization of cotton.

Analysis of Physiological and Biochemical Factors Affecting Flower Color of Herbaceous Peony in Different Flowering Periods

Herbaceous peony (Paeonia lactiflora Pall.) is a famous ornamental plant, and the study of its flower color is of great significance for cultivating new flower varieties. To explore the factors driving the formation and change of herbaceous peony flower color, we selected five herbaceous peony varieties at four flowering stages to determine the change in flower color, petal area, and microstructure. We also examined the composition and content of petal pigments, soluble sugar and soluble protein content, pH value of cell fluid, and water content. Finally, we analyzed the correlations between each factor. We found that Pn3G5G, Pg3G5G, and Cy3G5G were the main anthocyanin components in red and purple petals. Qu3G, Qu7G, Is3G, and lutein play important roles in yellow petal formation. The change in herbaceous peony flower color during the flowering process is directly caused by changes in the anthocyanin and carotenoid content in petals. In addition, changes in other physiological indices also influence the change in flower color. This study explored the physiological and biochemical factors affecting the color of herbaceous peony petals, which has an important practical significance for studying the physiological mechanism of herbaceous peony flower color formation and color breeding of new flowers.

Yellow Petal locus GaYP promotes flavonol biosynthesis and yellow coloration in petals of Asiatic cotton (Gossypium arboreum)

Yellow Petal locus GaYP is located on chromosome 11 and encodes a Sg6 R2R3-MYB transcription factor, which promotes flavonol biosynthesis and yellow coloration in Asiatic cotton petals. Petal color is pivotal to ornamental value and reproduction of plants. Yellow coloration in plant petals is mainly attributed to colorants including carotenoids, aurones and some flavonols. To date, the genetic regulatory mechanism of flavonol biosynthesis in petals is still to be elucidated. Here, we employed Asiatic cottons with or without deep yellow coloration in petals to address this question. Multi-omic and biochemical analysis revealed significantly up-regulated transcription of flavonol structural genes and increased levels of flavonols, especially gossypetin and 6-hydroxykaempferol, in yellow petals of Asiatic cotton. Furthermore, the Yellow Petal gene (GaYP) was mapped on chromosome 11 by using a recombinant inbred line population. It was found that GaYP encoded a transcriptional factor belonging to Sg6 R2R3-MYB proteins. GaYP could bind to the promoter of flavonol synthase gene (GaFLS) and activate the transcription of downstream genes. Knocking out of GaYP or GaFLS homologs in upland cotton largely eliminated flavonol accumulation and pale yellow coloration in petals. Our results indicated that flavonol synthesis, up-regulated by the R2R3-MYB transcription activator GaYP, was the causative factor for yellow coloration of Asiatic cotton petals. In addition, knocking out of GaYP homologs also led to decrease in anthocyanin accumulation and petal size in upland cotton, suggesting that GaYP and its homologs might modulate developmental or physiological processes beyond flavonol biosynthesis.

Maxillaria luizotavioi (Orchidaceae: Maxillariinae): a new species from the Oriental Brazilian Amazon

We describe and illustrate Maxillaria luizotavioi, a new orchid species from the Brazilian Amazon belonging to Maxillaria sect. Rufescens. The new species can be distinguished from Maxillaria cruentata from Colombia, the morphologically most similar species, by having pale yellow sepals and petals, lanceolate lateral sepals and dark vinous lip with rounded to obtuse apex. Additionally, we provide an identification key to the species of the section that occurs in Brazil.

Multiomics analysis reveals the mechanisms underlying the different floral colors and fragrances of Rosa hybrida cultivars

The color and fragrance of rose flowers affect their commercial value. However, several rose varieties with new floral colors developed by the bud mutation method lost their fragrance during the breeding process, raising the question: Is there a relationship between floral color and aroma traits? Rose cultivar ‘Yellow Island’ (YI) with intensely aroma and yellow petals, while its bud mutant ‘Past Feeling’ (PF) with light aroma and pink petals mixing some yellow, two cultivars were used to explore this question using multiomics approaches. We investigated the genomic polymorphisms between PF and YI by whole−genome resequencing. 71 differentially abundant metabolites and 155 related differentially expressed genes identified in petals between PF and YI. From this, we constructed a model of metabolic changes affecting floral color and fragrance integrating shikimate, terpenoid, carotenoid, and green leaf volatile metabolites and predicted the associated key genes and transcription factors. This study provides a reference for understanding the molecular mechanism of variation in rose floral color and aroma traits.

Mapping a mutation causing pale yellow petals in Brassica rapa.

Petal color is an important trait for both ornamental purposes and also for attracting pollinators. Here, we report a mutation of Brassica rapa R-o-18 with pale yellow petals that we retrieved from an EMS population and named whiter shade of pale ( wsp ). Phenotypic segregation ratio of an F2 mapping population indicates the phenotype is controlled by a single recessive gene. Mapping data from the whole genome sequencing coupled with allele frequency analysis suggests the mutation is located in a ~2 Mbp interval on chromosome 2. The interval contains a putative esterase/lipase/thioesterase protein previously demonstrated to account for floral color in B. rapa . We demonstrate that wsp carries a G to A missense mutation causing an aspartate to asparagine substitution within the putative lysophospholipid acyltransferase domain.

Transcriptome profiling reveals the roles of pigment formation mechanisms in yellow Paeonia delavayi flowers

The yellow colour of ornamental varieties of tree peony originated from Paeonia delavayi. However, but P. delavayi and Paeonia suffruticosa belong to different subgroups, so hybridization is difficult and results in a long breeding cycle. However, no comprehensive transcriptomic profiling has focused on the colour formation mechanisms of yellow tree peony petals. Analysing the colour formation mechanism of yellow petals in P. delavayi is very important for directional molecular breeding. In this study, the transcriptional map of yellow pigment development in petals was used to analyse the mechanism of petal colour formation. We analysed the genes related to the metabolism of flavonoids and carotenoids and the transcription factors (TFs) involved in P. delavayi var. lutea (pure yellow individual) yellow pigment development using transcriptome sequence profiling. Transcriptome sequence profiles revealed three and four differentially expressed transcripts (DETs) involved in flavonoid biosynthesis and carotenoid biosynthesis, respectively. An analysis of DETs in the flavonoid pathway showed that chalcone synthase (CHS) and chalcone 2´-glucosyltransferases (THC2’GT) act in synergy to synthesize isosalipurposide (ISP). CHS and flavonol synthase (FLS) synergistically synthesize quercetin and kaempferol. DEG analysis of the carotenoid pathway revealed that phytoene synthase (PSY), carotenoid isomerase (CRTISO) and β-carotene hydroxylases (CHYB) play a key role in regulating lutein formation, and carotenoid cleavage dioxygenase (CCD) plays an important role in the degradation of carotenoids. These two pathways may be regulated by TF families such as bHLH, ARF, and MYB. The results of the transient overexpression of genes showed that CHS and CHI are regulated by PdMYB2. In this study, the molecular mechanism of ISP synthesis was analysed in depth, and the complete metabolic pathway of carotenoids in Paeonia L. was reported for the first time. By studying the formation mechanism of yellow pigment in P. delavayi petals, a breeding strategy for improving flavonol and carotenoid contents and reducing anthocyanin synthesis by genetic engineering was suggested.