Pfaffia glomerata polyploid accession compromises male fertility and fetal development.

ETHNOPHARMACOLOGICAL RELEVANCE: Pfaffia glomerata (Spreng.) Pedersen has traditionally been used as a tonic and a stimulant by the Brazilian population. It shows higher biomass accumulation and production of secondary compounds, such as the phytosterol 20-hydroxyecdysone. AIMS: The present study aimed to evaluate the effects of the hydroalcoholic extract of the root of tetraploid P. glomerata (BGEt) on testicular parenchyma, and its implications on fertility. MATERIAL AND METHODS: Adult Swiss mice were divided as: control (water) and sildenafil citrate (7 mg/kg), BGEt at 100, 200, and 400 mg/kg, and BGEtD 200 mg/kg (treated with BGE every three days). Males (n = 4/group) were mated with normal untreated adult females to assess fertility rates, while other animals (n = 6/group) were euthanized for testis, epididymis, and oxidative stress analyses. RESULTS: Increase in tubule diameter and epithelium height in the discontinuous group, in addition to an increase in the proportion of tubules with moderate pathologies was observed. The pre-implantation loss was lower in all treated groups. The post-implantation loss was significantly increased in all treated groups, except for the lowest BGEt dose. BGEt intake caused a decrease in daily sperm production, along with the number and quality of sperm in the epididymis. Changes were observed in protein carbonylation and hydrogen peroxide and nitric oxide levels, characterizing oxidative stress. CONCLUSIONS: The hydroalcoholic extract of P. glomerata tetraploid altered sperm and testicular parameters, compromising embryonic development after implantation.

Comprehensive analysis of the GALACTINOL SYNTHASE (GolS) gene family in citrus and the function of CsGolS6 in stress tolerance.

Galactinol synthase (GolS) catalyzes the first and rate-limiting step in the synthesis of raffinose family of oligosaccharides (RFOs), which serve as storage and transport sugars, signal transducers, compatible solutes and antioxidants in higher plants. The present work aimed to assess the potential functions of citrus GolS in mechanisms of stress response and tolerance. By homology searches, eight GolS genes were found in the genomes of Citrus sinensis and C. clementina. Phylogenetic analysis showed that there is a GolS ortholog in C. clementina for each C. sinensis GolS, which have evolved differently from those of Arabidopsis thaliana. Transcriptional analysis indicated that most C. sinensis GolS (CsGolS) genes show a low-level tissue-specific and stress-inducible expression in response to drought and salt stress treatments, as well as to 'Candidatus Liberibacter asiaticus' infection. CsGolS6 overexpression resulted in improved tobacco tolerance to drought and salt stresses, contributing to an increased mesophyll cell expansion, photosynthesis and plant growth. Primary metabolite profiling revealed no significant changes in endogenous galactinol, but different extents of reduction of raffinose in the transgenic plants. On the other hand, a significant increase in the levels of metabolites with antioxidant properties, such as ascorbate, dehydroascorbate, alfa-tocopherol and spermidine, was observed in the transgenic plants. These results bring evidence that CsGolS6 is a potential candidate for improving stress tolerance in citrus and other plants.

Auxin-driven ecophysiological diversification of leaves in domesticated tomato.

Heterobaric leaves have bundle sheath extensions (BSEs) that compartmentalize the parenchyma, whereas homobaric leaves do not. The presence of BSEs affects leaf hydraulics and photosynthetic rate. The tomato (Solanum lycopersicum) obscuravenosa (obv) mutant lacks BSEs. Here, we identify the obv gene and the causative mutation, a nonsynonymous amino acid change that disrupts a C2H2 zinc finger motif in a putative transcription factor. This mutation exists as a polymorphism in the natural range of wild tomatoes but has increased in frequency in domesticated tomatoes, suggesting that the latter diversified into heterobaric and homobaric leaf types. The obv mutant displays reduced vein density, leaf hydraulic conductance and photosynthetic assimilation rate. We show that these and other pleiotropic effects on plant development, including changes in leaf insertion angle, leaf margin serration, minor vein density, and fruit shape, are controlled by OBV via changes in auxin signaling. Loss of function of the transcriptional regulator AUXIN RESPONSE FACTOR 4 (ARF4) also results in defective BSE development, revealing an additional component of a genetic module controlling aspects of leaf development important for ecological adaptation and subject to breeding selection.

The hidden half comes into the spotlight: Peeking inside the black box of root developmental phases.

Efficient use of natural resources (e.g., light, water, and nutrients) can be improved with a tailored developmental program that maximizes the lifetime and fitness of plants. In plant shoots, a developmental phase represents a time window in which the meristem triggers the development of unique morphological and physiological traits, leading to the emergence of leaves, flowers, and fruits. Whereas developmental phases in plant shoots have been shown to enhance food production in crops, this phenomenon has remained poorly investigated in roots. In light of recent advances, we suggest that root development occurs in three main phases: root apical meristem appearance, foraging, and senescence. We provide compelling evidence suggesting that these phases are regulated by at least four developmental pathways: autonomous, non-autonomous, hormonal, and periodic. Root developmental pathways differentially coordinate organ plasticity, promoting morphological alterations, tissue regeneration, and cell death regulation. Furthermore, we suggest how nutritional checkpoints may allow progression through the developmental phases, thus completing the root life cycle. These insights highlight novel and exciting advances in root biology that may help maximize the productivity of crops through more sustainable agriculture and the reduced use of chemical fertilizers.

Deleterious effects of Pfaffia glomerata (Spreng.) Pedersen hydroalcoholic extract on the seminiferous epithelium of adult Balb/c mice.

Several plant species such as Pfaffia glomerata are widely used in traditional Brazilian medicine as stimulants and aphrodisiacs. In this regard, the aim of our study was to explore the effects of the long-term intake of the hydro-alcoholic root extract of P glomerata on the germ and somatic cells within the seminiferous tubules in adult Balb/c mice. The experimental groups were placed as: controls (water and DMSO), and treated with 300 and 400 mg/kg of the root extract. The number of germ and somatic cells, the proportion of pathological seminiferous tubules, and the germ cell apoptotic levels were evaluated. The volume and proportion of the seminiferous epithelium was decreased after the extract intake due to the increased germ cell apoptotic levels. Vacuolization of Sertoli cell cytoplasm was observed widely in pathological tubules, along with fully disorganized epithelia, showing multinucleated cells, which lead to decreased daily sperm production. Taken together, our results indicate that long-term intake of the P glomerata caused deleterious effects on spermatogenesis by inducing apoptosis and altering the seminiferous tubule's epithelial dynamics.

Compatibility in pollen-pistil interaction of interspecific crossings with Passiflora spp.

Intraspecies or interspecies crossings transfer relevant alleles between plants. However, some interspecies crossings involving Passiflora species impede ovule fertilization and the viable development of seeds. Thus, the purpose of this study was to verify the viability of interspecific crossings and monitor pollen tube development. The experiment had six species of Passiflora in the reciprocal crossings. Histochemical tests aimed to evaluate the percentage of intraspecies or interspecies crossings that resulted in fruit development and pollen tube development. Ovule fertilization and fruit development occurred in determined directions of crossings when controlling the female or male genitor, but only one case of reciprocal crossing had success. In crossings with no fruit development, histological analysis showed that some callus developed in the stigma and style, confirming unilateral and interspecies incompatibility in the genus Passiflora to some species and some directions of crossings.

Somatic embryogenesis in the commercial papaya hybrid UENF/Caliman 01 relying on plantlet production from sexed adult hermaphrodite donor plants.

Somatic embryogenesis from explants from hermaphrodite papaya mother plants is an alternative for the production of true-to-type plants without the need for sexing. This study aimed to analyze hormonal and osmotic inducers in different somatic embryogenesis stages in the commercial hermaphrodite hybrid papaya UENF/Caliman 01. Leaf disks from in vitro shoots originated from ex vitro hermaphrodite plants were cultured in induction medium supplemented with different concentrations of 2,4-D (6, 9, 12, 15, and 18 µM) and 4-CPA (19, 22, 25, 28, and 31 µM). After 90 days, the formation of somatic embryos was verified. The 2,4-D induced the formation of light brown calli with low frequency (20%) of somatic embryogenesis. However, 4-CPA (25 µM) induced 96% of embryogenic calli, which were transferred to maturation medium (MM) and cultured for 30 days. The MM contained ABA (0.5 µM) and AC (15 g L-1) and produced 36.6 somatic embryos callus-1, mainly on cotyledonary stage. Cotyledonary embryos were transferred to germination medium supplemented with gibberellic acid (GA3) (0.0, 1.44, 2.88, and 4.32 µM), and the conversion into plantlets was enhanced with GA3 at 2.88 µM.

Leaf heteroblasty in Passiflora edulis as revealed by metabolic profiling and expression analyses of the microRNAs miR156 and miR172.

BACKGROUND AND AIMS: Juvenile-to-adult phase transition is marked by changes in leaf morphology, mostly due to the temporal development of the shoot apical meristem, a phenomenon known as heteroblasty. Sugars and microRNA-controlled modules are components of the heteroblastic process in Arabidopsis thaliana leaves. However, our understanding about their roles during phase-changing in other species, such as Passiflora edulis, remains limited. Unlike Arabidopsis, P. edulis (a semi-woody perennial climbing vine) undergoes remarkable changes in leaf morphology throughout juvenile-to-adult transition. Nonetheless, the underlying molecular mechanisms are unknown. METHODS: Here we evaluated the molecular mechanisms underlying the heteroblastic process by analysing the temporal expression of microRNAs and targets in leaves as well as the leaf metabolome during P. edulis development. KEY RESULTS: Metabolic profiling revealed a unique composition of metabolites associated with leaf heteroblasty. Increasing levels of glucose and α-trehalose were observed during juvenile-to-adult phase transition. Accumulation of microRNA156 (miR156) correlated with juvenile leaf traits, whilst miR172 transcript accumulation was associated with leaf adult traits. Importantly, glucose may mediate adult leaf characteristics during de novo shoot organogenesis by modulating miR156-targeted PeSPL9 expression levels at early stages of shoot development. CONCLUSIONS: Altogether, our results suggest that specific sugars may act as co-regulators, along with two microRNAs, leading to leaf morphological modifications throughout juvenile-to-adult phase transition in P. edulis.

The effects of an osmoregulator, carbohydrates and polyol on maturation and germination of 'Golden THB' papaya somatic embryos.

This study evaluated the effect of osmoregulators and carbohydrates on the maturation and germination of somatic embryos of papaya 'Golden THB'. Cotyledon explants from papaya seedlings germinated in vitro on basal MS medium were cultured on somatic embryogenesis induction medium (IM) containing MS salts, myo-inositol, sucrose, agar and p-chlorophenoxyacetic acid. After 50 days, embryogenic calli were transferred onto maturation media (MM) for 45 additional days. For experiment 1, a MS-based medium supplemented with abscisic acid, activated charcoal and concentrations of PEG 6000 (0; 40; 50; 60 and 70 g L-1) was used, whereas for experiment 2 malt extract concentrations (0; 0.1; 0.2; 0.3 and 0.4 g L-1) were assessed. The normal cotyledonary somatic embryos produced in experiment 2 were transferred to the germination medium (GM). The GM consisted of full-strength MS medium, sucrose, agar and was supplemented with myo-inositol at varying concentrations (0; 0.275; 0.55 and 0.825 mM). The PEG concentrations tested impaired the maturation of 'Golden THB' papaya somatic embryos. The MM, supplemented with malt extract at 0.153 g L-1, promoted the greatest development of normal somatic embryos (18.28 SE calli-1), that is, two cotyledonary leaves produced 36.56 SE calli-1. The supplementation with 0.45 mM myo-inositol provided the highest germination percentage (47.42%) and conversion to emblings.

Topological Data Analysis as a Morphometric Method: Using Persistent Homology to Demarcate a Leaf Morphospace.

Current morphometric methods that comprehensively measure shape cannot compare the disparate leaf shapes found in seed plants and are sensitive to processing artifacts. We explore the use of persistent homology, a topological method applied as a filtration across simplicial complexes (or more simply, a method to measure topological features of spaces across different spatial resolutions), to overcome these limitations. The described method isolates subsets of shape features and measures the spatial relationship of neighboring pixel densities in a shape. We apply the method to the analysis of 182,707 leaves, both published and unpublished, representing 141 plant families collected from 75 sites throughout the world. By measuring leaves from throughout the seed plants using persistent homology, a defined morphospace comparing all leaves is demarcated. Clear differences in shape between major phylogenetic groups are detected and estimates of leaf shape diversity within plant families are made. The approach predicts plant family above chance. The application of a persistent homology method, using topological features, to measure leaf shape allows for a unified morphometric framework to measure plant form, including shapes, textures, patterns, and branching architectures.

Selection and validation of reference genes for quantitative gene expression analyses in various tissues and seeds at different developmental stages in Bixa orellana L.

Bixa orellana L., popularly known as annatto, produces several secondary metabolites of pharmaceutical and industrial interest, including bixin, whose molecular basis of biosynthesis remain to be determined. Gene expression analysis by quantitative real-time PCR (qPCR) is an important tool to advance such knowledge. However, correct interpretation of qPCR data requires the use of suitable reference genes in order to reduce experimental variations. In the present study, we have selected four different candidates for reference genes in B. orellana, coding for 40S ribosomal protein S9 (RPS9), histone H4 (H4), 60S ribosomal protein L38 (RPL38) and 18S ribosomal RNA (18SrRNA). Their expression stabilities in different tissues (e.g. flower buds, flowers, leaves and seeds at different developmental stages) were analyzed using five statistical tools (NormFinder, geNorm, BestKeeper, ΔCt method and RefFinder). The results indicated that RPL38 is the most stable gene in different tissues and stages of seed development and 18SrRNA is the most unstable among the analyzed genes. In order to validate the candidate reference genes, we have analyzed the relative expression of a target gene coding for carotenoid cleavage dioxygenase 1 (CCD1) using the stable RPL38 and the least stable gene, 18SrRNA, for normalization of the qPCR data. The results demonstrated significant differences in the interpretation of the CCD1 gene expression data, depending on the reference gene used, reinforcing the importance of the correct selection of reference genes for normalization.

Somatic embryogenesis in Carica papaya as affected by auxins and explants, and morphoanatomical-related aspects

ABSTRACT The aim of this study was to evaluate somatic embryogenesis in juvenile explants of the THB papaya cultivar. Apical shoots and cotyledonary leaves were inoculated in an induction medium composed of different concentrations of 2,4-D (6, 9, 12, 15 and 18 µM) or 4-CPA (19, 22, 25, 28 and 31 µM). The embryogenic calluses were transferred to a maturation medium for 30 days. Histological analysis were done during the induction and scanning electron microscopy after maturing. For both types of auxin, embryogenesis was achieved at higher frequencies with cotyledonary leaves incubated in induction medium than with apical shoots; except for callogenesis. The early-stage embryos (e.g., globular or heart-shape) predominated. Among the auxins, best results were observed in cotyledonary leaves induced with 4-CPA (25 µM). Histological analyses of the cotyledonary leaf-derived calluses confirmed that the somatic embryos (SEs) formed from parenchyma cells, predominantly differentiated via indirect and multicellular origin and infrequently via synchronized embryogenesis. The secondary embryogenesis was observed during induction and maturation phases in papaya THB cultivar. The combination of ABA (0.5 µM) and AC (15 g L-1) in maturation medium resulted in the highest somatic embryogenesis induction frequency (70 SEs callus-1) and the lowest percentage of early germination (4%).

Somatic embryogenesis in Carica papaya as affected by auxins and explants, and morphoanatomical-related aspects.

The aim of this study was to evaluate somatic embryogenesis in juvenile explants of the THB papaya cultivar. Apical shoots and cotyledonary leaves were inoculated in an induction medium composed of different concentrations of 2,4-D (6, 9, 12, 15 and 18 µM) or 4-CPA (19, 22, 25, 28 and 31 µM). The embryogenic calluses were transferred to a maturation medium for 30 days. Histological analysis were done during the induction and scanning electron microscopy after maturing. For both types of auxin, embryogenesis was achieved at higher frequencies with cotyledonary leaves incubated in induction medium than with apical shoots; except for callogenesis. The early-stage embryos (e.g., globular or heart-shape) predominated. Among the auxins, best results were observed in cotyledonary leaves induced with 4-CPA (25 µM). Histological analyses of the cotyledonary leaf-derived calluses confirmed that the somatic embryos (SEs) formed from parenchyma cells, predominantly differentiated via indirect and multicellular origin and infrequently via synchronized embryogenesis. The secondary embryogenesis was observed during induction and maturation phases in papaya THB cultivar. The combination of ABA (0.5 µM) and AC (15 g L-1) in maturation medium resulted in the highest somatic embryogenesis induction frequency (70 SEs callus-1) and the lowest percentage of early germination (4%).

Erratum to: Morphometric analysis of Passiflora leaves: the relationship between landmarks of the vasculature and elliptical Fourier descriptors of the blade.

Background: Leaf shape among Passiflora species is spectacularly diverse. Underlying this diversity in leaf shape are profound changes in the patterning of the primary vasculature and laminar outgrowth. Each of these aspects of leaf morphology-vasculature and blade-provides different insights into leaf patterning. Results: Here, we morphometrically analyze >3300 leaves from 40 different Passiflora species collected sequentially across the vine. Each leaf is measured in two different ways: using 1) 15 homologous Procrustes-adjusted landmarks of the vasculature, sinuses, and lobes; and 2) Elliptical Fourier Descriptors (EFDs), which quantify the outline of the leaf. The ability of landmarks, EFDs, and both datasets together are compared to determine their relative ability to predict species and node position within the vine. Pairwise correlation of x and y landmark coordinates and EFD harmonic coefficients reveals close associations between traits and insights into the relationship between vasculature and blade patterning. Conclusions: Landmarks, more reflective of the vasculature, and EFDs, more reflective of the blade contour, describe both similar and distinct features of leaf morphology. Landmarks and EFDs vary in ability to predict species identity and node position in the vine and exhibit a correlational structure (both within landmark or EFD traits and between the two data types) revealing constraints between vascular and blade patterning underlying natural variation in leaf morphology among Passiflora species.

Morphometric analysis of Passiflora leaves: the relationship between landmarks of the vasculature and elliptical Fourier descriptors of the blade.

Background: Leaf shape among Passiflora species is spectacularly diverse. Underlying this diversity in leaf shape are profound changes in the patterning of the primary vasculature and laminar outgrowth. Each of these aspects of leaf morphology-vasculature and blade-provides different insights into leaf patterning. Results: Here, we morphometrically analyze >3300 leaves from 40 different Passiflora species collected sequentially across the vine. Each leaf is measured in two different ways: using 1) 15 homologous Procrustes-adjusted landmarks of the vasculature, sinuses, and lobes; and 2) Elliptical Fourier Descriptors (EFDs), which quantify the outline of the leaf. The ability of landmarks, EFDs, and both datasets together are compared to determine their relative ability to predict species and node position within the vine. Pairwise correlation of x and y landmark coordinates and EFD harmonic coefficients reveals close associations between traits and insights into the relationship between vasculature and blade patterning. Conclusions: Landmarks, more reflective of the vasculature, and EFDs, more reflective of the blade contour, describe both similar and distinct features of leaf morphology. Landmarks and EFDs vary in ability to predict species identity and node position in the vine and exhibit a correlational structure (both within landmark or EFD traits and between the two data types) revealing constraints between vascular and blade patterning underlying natural variation in leaf morphology among Passiflora species.

Divergent leaf shapes among Passiflora species arise from a shared juvenile morphology.

Not only does leaf shape vary between Passiflora species, but between sequential nodes of the vine. The profound changes in leaf shape within Passiflora vines reflect the temporal development of the shoot apical meristem from which leaves are derived and patterned, a phenomenon known as heteroblasty. We perform a morphometric analysis of more than 3,300 leaves from 40 different Passiflora species using two different methods: homologous landmarks and Elliptical Fourier Descriptors (EFDs). Changes in leaf shape across the vine are first quantified in allometric terms; that is, changes in the relative area of leaf subregions expressed in terms of overall leaf area. Shape is constrained to strict linear relationships as a function of size that vary between species. Statistical analysis of leaf shape, using landmarks and EFDs, reveals that species effects (regardless of node) are the strongest, followed by interaction effects between species and heteroblasty (i.e., species-specific patterns in leaf shape across nodes) and that heteroblasty effects across nodes (regardless of species) are negligible. The ability of different nodes to predictively discriminate species and the variability of landmark and EFD traits at each node is then analyzed. Heteroblastic trajectories, the changes in leaf shape between the first and last measured leaves in a vine, are then compared between species in a multivariate space. Leaf shape diversity among Passiflora species is expressed in a heteroblastic-dependent manner, unique to each species. Leaf shape is constrained by linear, allometric relationships related to leaf size that vary between species. There is a strong species × heteroblasty interaction effect for leaf shape, suggesting that different leaf shapes between species arise through changes in shape across nodes specific to each species. The first leaves in the series are not only more like each other, but are also less variable across species. From this similar, shared leaf shape, subsequent leaves in the heteroblastic series follow divergent morphological trajectories. The disparate leaf shapes characteristic of Passiflora species arise from a shared, juvenile morphology.

Positive selection on the K domain of the AGAMOUS protein in the Zingiberales suggests a mechanism for the evolution of androecial morphology.

BACKGROUND: The ABC model of flower development describes the molecular basis for specification of floral organ identity in model eudicots such as Arabidopsis and Antirrhinum. According to this model, expression of C-class genes is linked to stamen and gynoecium organ identity. The Zingiberales is an order of tropical monocots in which the evolution of floral morphology is characterized by a marked increase in petaloidy in the androecium. Petaloidy is a derived characteristic of the ginger families and seems to have arisen in the common ancestor of the ginger clade. We hypothesize that duplication of the C-class AGAMOUS (AG) gene followed by divergence of the duplicated AG copies during the diversification of the ginger clade lineages explains the evolution of petaloidy in the androecium. In order to address this hypothesis, we carried out phylogenetic analyses of the AG gene family across the Zingiberales and investigated patterns of gene expression within the androecium. RESULTS: Phylogenetic analysis supports a scenario in which Zingiberales-specific AG genes have undergone at least one round of duplication. Gene duplication was immediately followed by divergence of the retained copies. In particular, we detect positive selection in the third alpha-helix of the K domain of Zingiberales AGAMOUS copy 1 (ZinAG-1). A single fixed amino acid change is observed in ZinAG-1 within the ginger clade when compared to the banana grade. Expression analyses of AG and APETALA1/FRUITFULL (AP1/FUL) in Musa basjoo is similar to A- and C-class gene expressions in the Arabidopsis thaliana model, while Costus spicatus exhibits simultaneous expression of AG and AP1/FUL in most floral organs. We propose that this novel expression pattern could be correlated with the evolution of androecial petaloidy within the Zingiberales. CONCLUSIONS: Our results present an intricate story in which duplication of the AG lineage has lead to the retention of at least two diverged Zingiberales-specific copies, ZinAG-1 and Zingiberales AGAMOUS copy 2 (ZinAG-2). Positive selection on ZinAG-1 residues suggests a mechanism by which AG gene divergence may explain observed morphological changes in Zingiberales flowers. Expression data provides preliminary support for the proposed mechanism, although further studies are required to fully test this hypothesis.

Antigen production using heterologous expression of dengue virus-2 non-structural protein 1 (NS1) in Nicotiana tabacum (Havana) for immunodiagnostic purposes.

KEY MESSAGE: Expression of dengue-2 virus NS1 protein in Nicotiana tabacum plants for development of dengue immunodiagnostic kits. Dengue is one of the most important diseases caused by arboviruses in the world. A significant increase in its geographical distribution has been noticed over the last 20 years, with continuous transmission of several serotypes and emergence of the hemorrhagic fever in areas where the disease was previously not prevalent. Although the methodological processes for dengue diagnosis are in deep development and improvement, a limitation for the realization of dengue diagnostic tests is the difficulty of large-scale production of the antigen to be used in diagnostic tests. Due to this demand, the purpose of this study was to obtain the non-structural protein 1 (NS1) from dengue-2 serotype by heterologous expression in Nicotiana tabacum (Havana). After confirmation of the NS1 protein gene integration in the plant genome, the heterologous protein was characterized using SDS-PAGE and immunoblotting. In an immunoenzymatic test, the recombinant NS1 protein presents an antigen potential for development of dengue immunodiagnostic kits.

Characterization and developmental expression of genes encoding the early carotenoid biosynthetic enzymes in Citrus paradisi Macf.

In the present study, the full-length cDNA sequences of PSY, PDS, and ZDS, encoding the early carotenoid biosynthetic enzymes in the carotenoid pathway of grapefruit (Citrus paradisi), were isolated and characterized for the first time. CpPSY contained a 1311-bp open reading frame (ORF) encoding a polypeptide of 436 amino acids, CpPDS contained a 1659-bp ORF encoding a polypeptide of 552 amino acids, and CpZDS contained a 1713-bp ORF encoding a polypeptide of 570 amino acids. Phylogenetic analysis indicated that CpPSY shares homology with PSYs from Citrus, tomato, pepper, Arabidopsis, and the monocot PSY1 group, while CpPDS and CpZDS are most closely related to orthologs from Citrus and tomato. Expression analysis revealed fluctuations in CpPSY, CpPDS, and CpZDS transcript abundance and a non-coordinated regulation between the former and the two latter genes during fruit development in albedo and juice vesicles of white ('Duncan') and red ('Flame') grapefruits. A 3× higher upregulation of CpPSY expression in juice vesicles of red-fleshed 'Flame' as compared to white-fruited 'Duncan' was observed in the middle stages of fruit development, which correlates with the well documented accumulation pattern of lycopene in red grapefruit. Together with previous data, our results suggest that the primary mechanism controlling lycopene accumulation in red grapefruit involves the transcriptional upregulation of CpPSY, which controls the flux into the carotenoid pathway, and the downregulated expression of CpLCYB2, which controls the step of cyclization of lycopene in chromoplasts during fruit ripening. A correlation between CpPSY expression and fruit color evolution in red grapefruit is demonstrated.