Fleshy-fruited Species Research Articles

Year-round presence of Slaty Thrush (Turdus nigriceps nigriceps) in mountains of central Argentina

The migration patterns of passerine species in the Neotropical region present several gaps of knowledge. The migratory behavior of the Slaty Thrush ( Turdus nigriceps nigriceps ) has been well characterized in their central and northern distribution along eastern slopes of the Andes from Argentina to Ecuador. The Slaty Thrush was historically considered a migrant breeder in the southern extreme of their distribution. In the present study, we show new evidence of the resident status of this species in its southernmost distribution on western slopes of Sierras Grandes and Sierras de Comechingones in Cordoba Province, Argentina. There, the Slaty Thrush has a year-round presence only at sites invaded by fleshy-fruited alien plants. The main invasive plants form dense patches of vegetation and offer an abundant fruit supply that is highly consumed by this bird species during autumn–winter, when there are no native fruits available. We suggest that the Slaty Thrush was a migrant species in past decades, but the recent invasion by fleshy-fruited species could explain its actual year-round presence by providing fruit in a period of the year of food shortage and new suitable habitats.

Are birds, wind and gravity legitimate dispersers of fleshy-fruited invasive plants on Robinson Crusoe Island, Chile?

Although fleshy-fruited species are usually dispersed by animals and gravity, previous research shows that the fleshy fruits of invasive plants on Robinson Crusoe Island (RC) are also moved by wind. To determine whether a bird (Turdus falcklandii), wind, and gravity could be legitimate dispersers of fleshy fruits from the invasive plant species Aristotelia chilensis, Rubus ulmifolius and Ugni molinae, we carried out germination trials with seeds defecated by T. falcklandii and hand-cleaned in the laboratory, and added another trial in field conditions, sowing intact fruits. Whole fruits sown intact are used to represent dispersal by wind or gravity. The field trials for A. chilensis and R. ulmifolius were performed in canopy gaps and closed forests to evaluate the effect of shadow on seedling emergence. Field trials for U. molinae were only established in open shrubland, since this species does not occur in forests on RC. Laboratory trials showed gut-passed A. chilensis seeds increased the germination percentage while gut-passed seeds did not affect germination in R. ulmifolius and U. molinae. In the field, trials revealed that seeds from intact fruits germinated in a similar way to gut-passed or hand-cleaned seeds, with the exception of U. molinae, which did not germinate inside fruits. In all field treatments, the germination percentage of A. chilensis and R. ulmifolius was higher in the canopy gaps than under closed canopy. These results indicate that T. falcklandii is a legitimate disperser for the three invasive species studied on RC. Wind and gravity should also be considered legitimate dispersers of A. chilensis and R. ulmifolius. Microhabitat (i.e., canopy gaps) plays a more important role in improving the establishment of A. chilensis and R. ulmifolius than the dispersal mechanism itself.

Rapid spread of a fleshy-fruited species in abandoned subalpine meadows - formation of an unusual forest belt in the eastern Carpathians

In recent decades, most subalpine hay meadows and pastures have been abandoned, and trees have been recolonizing these sites where forest existed before agricultural activity. This study examined how woody vegetation, dominated by the deciduous fleshy-fruited tree Sorbus aucuparia (rowan), expanded on subalpine meadows in the Western Bieszczady Mountains (eastern Carpathians, Poland) after the cessation of agricultural use. The aims were to determine the abundance of rowan in the woody vegetation, to estimate the rate of rowan expansion in the studied area, and to characterize the variability of rowan stands and growth forms. Rowan dominated the current plant community of abandoned subalpine meadows, though this species is not considered a rapid colonizer of open areas and was not frequent in the uppermost forest belt before the colonization. The whole area was encroached by rowans in a very short period of time 60-70 years ago. Rowan tree density was similar throughout the elevational gradient but the growth form changed, becoming more shrub-like with increasing elevation. Rowan stands will likely be the main element of the subalpine belt in this region in the upcoming decades. At present, no tree species can be considered a rapid successor to rowan in the area.

Importancia ecológica de los mamíferos frugívoros en la dinámica de regeneración de tierras abandonadas en ambientes mediterráneos

Escribano-Ávila, G., Pías, B., Escudero, A., Virgós, E. 2015. Ecological relevance of frugivorous mammals in the regeneration dynamics of old fields in Mediterranean environments. Ecosistemas 24(3): 35-42. Doi.: 10.7818/ECOS.2015.24-3.06 Two opposite tendencies govern land use worldwide: intensification and abandonment. Land abandonment represents an opportunity for ecosystem recovery, an urgent need due to the current environmental crisis. Dispersal communities play a key role in the recovery of old fields, as they mobilize seeds that serve as the primary source for the regeneration of woody plants. Recent studies have pointed out the special relevance of frugivorous mammals for seed dispersal in degraded environments such as old fields. This is due to morphological and behavioural traits of frugivorous mammals which make this dispersal guild especially effective. Frugivorous mammals are generally bigger body-sized, use bigger home ranges and are able to perform longer dispersal distances than other frugivorous, thus dispersing a greater quantity of seeds in old fields. Once a seed arrives to an old field several stages until recruitment should be overcome (post-dispersal predation, germination, survival and growth). Seed dispersal by frugivorous mammals favors the success of dispersed seeds to be recruited due to: i. At the inter-specific level, frugivorous mammals do not present gape width limitations, thereby dispersing a wide range of fleshy fruited species. At the intra-specific level they are able to consume all fruit/seed size ranges while smaller frugivorous, like small to medium sized birds, usually select small fruits which may hamper recruitment, and ii Mammal frugivorous, specially carnivores, deposit seeds in microhabitats specially suitable for woody plants recruitment (e.g. shrubs). Overall, mammal frugivorous are key members of dispersal communities promoting regeneration dynamics in old fields thereby their ecological function should be considered from a management and restoration perspective.

On the Limited Potential of Azorean Fleshy Fruits for Oceanic Dispersal.

How plants arrived to originally sterile oceanic islands has puzzled naturalists for centuries. Dispersal syndromes (i.e., diaspore traits that promote dispersal by long-distance dispersal vectors), are generally considered to play a determinant role in assisting island colonization. However, the association between diaspore traits and the potential vectors by which diaspores are dispersed is not always obvious. Fleshy fruits, in particular, are considered to have evolved to promote the internal dispersal of seeds by frugivores (endozoochory), however some fleshy fruits can also float in saltwater, and thus be potentially transported by oceanic current (thalassochory). We performed saltwater floatation and viability experiments with fruits of the 14 European fleshy-fruited species that naturally colonized the Azores archipelago (North Atlantic Ocean). We show that only Corema album (a berry) and Juniperus oxycedrus (a fleshy cone) floated for as long as 60 days, the estimated minimum time needed to reach the Azores by oceanic currents. Regardless the floatation potential, exposure to saltwater largely reduced the viability of most seeds of the 14 species (46% of viability decline within 15 days and 77% within 60 days of immersion), including those of Corema album (61%) and Juniperus oxycedrus (83%). Floatability and viability trials suggest that while some fleshy-fruited species might have arrived to the Azores by oceanic currents, such would have required extreme meteorological events that could largely reduce the duration of the trip. Thus, the alternative hypothesis that fleshy-fruited species were mostly dependent on animal dispersers (endozoochory) to colonize these remote islands is reinforced.

Contagious seed dispersal and the spread of avian-dispersed exotic plants

Seed dispersal by avian frugivores has driven the invasive success of numerous exotic fleshy-fruited plant species around the world. Birds’ movements are often directed toward food sources, producing seed shadows that are highly structured in space. The distribution of native fleshy-fruited plants in a landscape could thus form a spatial template for the contagious spread of exotic fleshy-fruited species in the early stages of invasion. We compared seed rain beneath fleshy-fruited and dry-fruited native-tree canopies in forested habitats and open fields in southeastern Michigan. We predicted that exotic seed rain would be highest beneath the canopies of fleshy-fruited plants, and that localities with higher densities of fruit-bearing fleshy-fruited plants would receive more exotic seed rain. Our results suggest that the seed shadows of exotic fleshy-fruited species are strongly influenced by the spatial distributions of native fleshy-fruited trees, and by the local density of fleshy-fruited plants. Over 92 % of exotic seeds were dispersed beneath fleshy-fruited trees, whereas less than 8 % of exotic seeds were dispersed beneath dry-fruited trees. Exotic seed rain was positively related to the local density of fleshy-fruited plants in forest, but not in open fields. Our study shows how shared dispersal syndromes and frugivore behavior influence the seed shadows of avian-dispersed exotic plants, enabling spatially explicit predictions of invasive spread in their novel ranges.

Wide-genome QTL mapping of fruit quality traits in a tomato RIL population derived from the wild-relative species Solanum pimpinellifolium L.

QTL and candidate genes associated to fruit quality traits have been identified in a tomato genetic map derived from Solanum pimpinellifolium L., providing molecular tools for marker-assisted breeding. The study of genetic, physiological, and molecular pathways involved in fruit development and ripening has considered tomato as the model fleshy-fruited species par excellence. Fruit quality traits regarding organoleptic and nutritional properties are major goals for tomato breeding programs since they largely decide the acceptance of tomato in both fresh and processing markets. Here we report the genetic mapping of single-locus and epistatic quantitative trait loci (QTL) associated to the fruit size and content of sugars, acids, vitamins, and carotenoids from the characterization of a RIL population derived from the wild-relative Solanum pimpinellifolium TO-937. A genetic map composed of 353 molecular markers including 13 genes regulating fruit and developmental traits was generated, which spanned 1007cM with an average distance between markers of 2.8cM. Genetic analyses indicated that fruit quality traits analyzed in this work exhibited transgressive segregation and that additive and epistatic effects are the major genetic basis of fruit quality traits. Moreover, most mapped QTL showed environment interaction effects. FrW7.1 fruit size QTL co-localized with QTL involved in soluble solid, vitamin C, and glucose contents, dry weight/fresh weight, and most importantly with the Sucrose Phosphate Synthase gene, suggesting that polymorphisms in this gene could influence genetic variation in several fruit quality traits. In addition, 1-deoxy-D-xylulose 5-phosphate synthase and Tocopherol cyclase genes were identified as candidate genes underlying QTL variation in beta-carotene and vitamin C. Together, our results provide useful genetic and molecular information regarding fruit quality and new chances for tomato breeding by implementing marker-assisted selection.

Seed shattering: from models to crops.

Seed shattering (or pod dehiscence, or fruit shedding) is essential for the propagation of their offspring in wild plants but is a major cause of yield loss in crops. In the dicot model species, Arabidopsis thaliana, pod dehiscence necessitates a development of the abscission zones along the pod valve margins. In monocots, such as cereals, an abscission layer in the pedicle is required for the seed shattering process. In the past decade, great advances have been made in characterizing the genetic contributors that are involved in the complex regulatory network in the establishment of abscission cell identity. We summarize the recent burgeoning progress in the field of genetic regulation of pod dehiscence and fruit shedding, focusing mainly on the model species A. thaliana with its close relatives and the fleshy fruit species tomato, as well as the genetic basis responsible for the parallel loss of seed shattering in domesticated crops. This review shows how these individual genes are co-opted in the developmental process of the tissues that guarantee seed shattering. Research into the genetic mechanism underlying seed shattering provides a premier prerequisite for the future breeding program for harvest in crops.

Toxic Fruits in the Diet of Carnivores in Poland

There is a lack of documentation on the consumption of toxic fruits by carnivores. To quantify the importance of toxic fruits in the diets of badgers (Meles meles), foxes (Vulpes vulpes) and martens (Martes sp.), we collected faeces of these animals along nine transects (total 30.4 km long, 2 m wide) during the fruiting seasons (June–November) in 2010 and 2011. From 619 faecal samples we found seeds of 16 fleshy-fruited plant species, including four species with toxic fruits. Surprisingly, the fruit of Convallaria majalis having a high content of toxic substances was also eaten by these animals. Fruits of C. majalis were found in faeces in late summer/autumn after early frost when maturing processes had reduced the content of toxic substances in the mesocarp. Toxic fruits were detected in 6.3% of all faeces sampled (n = 619). The proportion of toxic fruits in the diet was the highest (up to 10.5%) in martens as compared with that in badgers and foxes (2.2% and 0.7%, respectively).

Transcriptional Activity of the MADS Box ARLEQUIN/TOMATO AGAMOUS-LIKE1 Gene Is Required for Cuticle Development of Tomato Fruit.

Fruit development and ripening entail key biological and agronomic events, which ensure the appropriate formation and dispersal of seeds and determine productivity and yield quality traits. The MADS box gene Arlequin/tomato Agamous-like1 (hereafter referred to as TAGL1) was reported as a key regulator of tomato (Solanum lycopersicum) reproductive development, mainly involved in flower development, early fruit development, and ripening. It is shown here that silencing of the TAGL1 gene (RNA interference lines) promotes significant changes affecting cuticle development, mainly a reduction of thickness and stiffness, as well as a significant decrease in the content of cuticle components (cutin, waxes, polysaccharides, and phenolic compounds). Accordingly, overexpression of TAGL1 significantly increased the amount of cuticle and most of its components while rendering a mechanically weak cuticle. Expression of the genes involved in cuticle biosynthesis agreed with the biochemical and biomechanical features of cuticles isolated from transgenic fruits; it also indicated that TAGL1 participates in the transcriptional control of cuticle development mediating the biosynthesis of cuticle components. Furthermore, cell morphology and the arrangement of epidermal cell layers, on whose activity cuticle formation depends, were altered when TAGL1 was either silenced or constitutively expressed, indicating that this transcription factor regulates cuticle development, probably through the biosynthetic activity of epidermal cells. Our results also support cuticle development as an integrated event in the fruit expansion and ripening processes that characterize fleshy-fruited species such as tomato.

Differences in phenology and fruit characteristic between invasive and native woody species favor exotic species invasiveness

This study evaluates the idea that differences in reproductive phenology and traits between coexisting exotic and native species may promote exotic invasiveness. Reproductive phenology, proportions of flowers setting unripe fruits and ripe fruits (fruit set), abundance and morphology of fruits, and seed viability were compared between two invasive (Crataegus monogyna and Sorbus aucuparia) and six native woody fleshy-fruited species at three sites in temperate forests of northwestern Patagonia, Argentina. Flowering and the onset of fruit ripening occurred later in the exotic species than in most of the native species. The exotic species differed between them in some aspects of the reproductive process: C. monogyna had a higher fruit set, whereas S. aucuparia produced more flowers which offset its low values of fruit set. In both the exotic species and one simultaneously fruiting native species (Schinus patagonicus), high numbers of ripe fruits with a high proportion of viable seeds remained on the plants at a time when fruits of other native species were either scarce or absent (autumn–winter period). Compared to the fruits of S. patagonicus, those of both the exotic species are larger and fleshier. Therefore, the fruits of both the exotic species offer the dispersers, especially birds which were the most important frugivores in these studied temperate forests, a resource that would not be provided by the native plants. The success of these exotic species in Patagonian forests appears to be attributable in part to differences in their reproductive attributes such as fruit phenology and fruit traits such as size and fleshiness.

Fruit development and ripening.

Fruiting structures in the angiosperms range from completely dry to highly fleshy organs and provide many of our major crop products, including grains. In the model plant Arabidopsis, which has dry fruits, a high-level regulatory network of transcription factors controlling fruit development has been revealed. Studies on rare nonripening mutations in tomato, a model for fleshy fruits, have provided new insights into the networks responsible for the control of ripening. It is apparent that there are strong similarities between dry and fleshy fruits in the molecular circuits governing development and maturation. Translation of information from tomato to other fleshy-fruited species indicates that regulatory networks are conserved across a wide spectrum of angiosperm fruit morphologies. Fruits are an essential part of the human diet, and recent developments in the sequencing of angiosperm genomes have provided the foundation for a step change in crop improvement through the understanding and harnessing of ge...

Differential Effect of Fruit Availability on Avian Frugivore Guilds in a Moist Deciduous Forest of India

Frugivores provide a critical ecosystem service by dispersing seeds and therefore play a major role in the survival and maintenance of trees in tropical forests. Avian frugivores constitute one of the major guilds in tropical forests whose activities are significantly governed by the availability of fruits across space and time. In our current study we examined the effects of the spatial and temporal pattern of food availability on avian frugivores and various avian frugivore functional groups in particular. We found a differential effect of fruit density and number of tree species in fruiting on different functional groups of avian frugivores along both spatial and temporal scales. Total frugivore density was best explained by ‘number of tree species in fruiting’ at both special and temporal scale. The variation in large frugivore density was best explained both by ‘fruit density’ and ‘fruit density’ and ‘number of tree species in fruiting’ together. This pattern was observed at a spatial scale but not along temporal scale. Along temporal scale large frugivore density was best explained only by ‘number of tree species in fruiting’. The medium sized frugivore density was not significantly explained by either ‘fruit density’ or ‘number of tree species in fruiting’. The medium sized frugivores are dependent both on insects and fruits and variation in insect density may determine spatial and temporal variation in medium sized frugivore density. The mixed diet frugivore group with a smaller gape width is limited by the variety of fruit they consume and thus their population was significantly controlled by the number of fleshy fruited tree species in fruiting along spatial scale. We observed breeding synchronization during the time of fruiting peak and we suggest that this could be a strategy for effective seed dispersal. Our study indicated very strong dependability of the large frugivore (dependent only on fruit) population on fruit availability unlike the mixed diet frugivore guild (fruit as secondary diet).

Ethylene Regulates Apple (Malus × domestica) Fruit Softening Through a Dose × Time-Dependent Mechanism and Through Differential Sensitivities and Dependencies of Cell Wall-Modifying Genes

In fleshy fruit species that have a strong requirement for ethylene to ripen, ethylene is synthesized autocatalytically, producing increasing concentrations as the fruits ripen. Apple fruit with the ACC OXIDASE 1 (ACO1) gene suppressed cannot produce ethylene autocatalytically at ripening. Using these apple lines, an ethylene sensitivity dependency model was previously proposed, with traits such as softening showing a high dependency for ethylene as well as low sensitivity. In this study, it is shown that the molecular control of fruit softening is a complex process, with different cell wall-related genes being independently regulated and exhibiting differential sensitivities to and dependencies on ethylene at the transcriptional level. This regulation is controlled through a dose × time mechanism, which results in a temporal transcriptional response that would allow for progressive cell wall disassembly and thus softening. This research builds on the sensitivity dependency model and shows that ethylene-dependent traits can progress over time to the same degree with lower levels of ethylene. This suggests that a developmental clock measuring cumulative ethylene controls the fruit ripening process.

The Effects of Mega-Herbivore Extinctions on Seed Dispersal and Community Structure in An East African Savanna

Herbivory is a prominent top-down force shaping the landscape of semiarid savannas in East Africa. Herbivores participate in seed dispersal both by ingesting and defecating the seeds of endozoochorously-dispersed plants and by translocating the seeds of exozoochorously-dispersed plants. In this study, we sought to determine how the extinction of large mammalian herbivores would affect the abundance of five focal species of plants that use fruiting as their primary dispersal mechanism. We also examined how the absence of large mammalian herbivores affected seed predation by small mammals. We counted the number of individual plants for each of the five species in three short-term (5 year old) exclusion blocks and one long-term (15 year old) exclusion block. We found that total abundance of fleshy-fruited species increased as successive levels of large mammalian herbivores were excluded and as the duration of herbivore exclusion increased. Within species, we found that C. orthacantha and S. campylacanthum increased in the absence of herbivores, while O. stricta decreased in the absence of herbivores. B. aegyptiaca and B. albitrunca did not exhibit differences in abundance between different levels of herbivore exclosure. We found that small mammals demonstrated a preference for B. albitrunca and O. stricta seeds, which were consumed primarily by the fringe-tailed gerbil, Gerbilliscus robustus. Understanding the interactions between herbivores and vegetation is vital to conserving plant communities as well as understanding how they may change in the future.

Ecosystem impacts of folivory and frugivory by Japanese macaques in two temperate forests in Yakushima

Comparing animal consumption to plant primary production provides a means of assessing an animal's impact on the ecosystem and an evaluation of resource limitation. Here, we compared annual fruit and leaf consumption by Japanese macaques (Macaca fuscata) relative to the annual production of these foods in the lowlands and highlands of Yakushima Island, Japan. We estimated consumption by macaques by the direct observation of macaque groups for 1 year in each habitat. We estimated leaf production as the sum of leaf litter fall (corrected for the effect of translocated organic and inorganic matter) and folivory by insects (assumed to be 10%) and by macaques. We estimated fruit production as the sum of fruit litter fall and consumption by birds (estimated by the seed fall) and macaques. The impact of macaque folivory at the community level was negligible relative to production (∼0.04%) compared with folivory by insects (assumed to be 10%); however, for some species, macaque folivory reached up to 10.1% of production. Tree species on which macaques fed did not decline in abundance over 13 years, suggesting that their folivory did not influence tree species dynamics. For the three major fleshy-fruited species in the highland site, macaques consumed a considerable portion of total fruit production (6-40%), rivaling the consumption by birds (32-75%). We conclude that at the community level, macaque folivory was negligible compared with the leaf production, but frugivory was not.

Life history traits and patterns of diversification in oceanic archipelagos: a meta-analysis

Ecological conditions, such as high habitat diversity and the absence of competitors, have been proposed as key determinants of the patterns of speciation observed in oceanic island floras. However, the relationship between plant traits and lineage diversification has received less attention. Here, we review 120 published phylogenetic and population genetic studies of three well-studied oceanic archipelagos (Canary Islands, Galapagos and Hawai'i) to investigate potential associations between life history characters (growth form and fruit type) and patterns of diversification. The available data suggest that the phenotypic syndrome 'herbaceous-dry fruited' was predominant among ancestors of species-rich lineages, although the Hawaiian flora also shows a substantial proportion of 'woody-fleshy fruited' ancestors. Growth form, unlike fruit type, is shown to be a labile character strongly selected for woodiness, particularly in radiating lineages. Dry fruits, although representative of diverse dispersal modes and efficacies, are generally associated with a low incidence of inter-island colonization, and the analysis of population genetic data confirms strong genetic differentiation among islands for dry fruited species of radiating lineages. In contrast, fleshy fruited species of monotypic lineages typically show widespread distributions coupled with extensive gene flow among islands, which probably impedes speciation. Our analyses suggest that fruit types associated with limited evidence of dispersal promote recurrent speciation within lineages, although particular character states related to speciation appear to be context dependent. This study reinforces the idea that plant traits associated with island colonization and population persistence are, in addition to ecological conditions, important factors in understanding the patterns of diversification on islands. © 2013 The Linnean Society of London.

How fruit developmental biology makes use of flow cytometry approaches

Fleshy fruit species such as tomato are important because of their nutritional and economic value. Several stages of fruit development such as ovary formation, fruit set, and fruit maturation have already been the subject of many developmental studies. However, fruit growth per se has been much less addressed. Fruit growth like all plant organs depends upon the developmental processes of cell division and cell expansion. The activity of cell divisions sets the number of cells that will compose the fruit; the cell expansion activity then determines its final size. Among the various mechanisms that may influence the determination of cell size, endopolyploidy by the means of endoreduplication, i.e. genome amplification in the absence of mitosis, appears to be of great importance in fleshy fruits. In tomato fruit, endoreduplication is associated with DNA-dependent cell expansion: cell size can reach spectacular levels such as hundreds of times its initial size (e.g. >0.5 mm in diameter), with as much as a 256-fold increase in nuclear DNA content. Using tomato fruit development as a model, recent investigations combining the use of flow cytometry, cellular imaging and molecular analyses have provided new data in favor of the long-standing karyoplasmic ratio theory, stating that cells tend to adjust their cytoplasmic volume to the nuclear DNA content. By establishing a highly structured cellular system where multiple physiological functions are integrated, endoreduplication acts as a morphogenetic factor supporting cell growth during tomato fruit development. In the context of plant breeding, deciphering the mechanisms controlling fruit growth, in particular those connecting the process of nuclear endoreduplication with modulation of gene expression, the regulation of cell size and final fruit size and composition, is necessary to understand better the establishment of fleshy fruit quality traits.

Comparative ecology of bird-pollinated and bird-dispersed New Zealand plants

I observed birds forage for flowers and fruits for six consecutive years in a North Island forest to compare patterns in nectivory and frugivory in plants that rely on birds for both mutualistic services. Birds visited fewer flowering plant species (n=9) than fleshy fruited plant species (n=23). Four ‘bird plant’ species were identified (i.e., plant species that are co-dependent on birds for both pollination and seed dispersal). Visitation rates to flowers produced by bird plants were correlated with visitation rates to fruits, indicating that if a bird plant relied heavily on a particular bird species to visit its flowers, it tended to rely on the same bird species to visit its fruits. Coupled rates nectivory and frugivory raises a significant conservation concern, as it indicates that the loss of specific bird species may have a two-fold, negative effect on the reproductive fitness of plants that rely on birds for both pollination and seed dispersal.

Cell number regulator genes in Prunus provide candidate genes for the control of fruit size in sweet and sour cherry

Striking increases in fruit size distinguish cultivated descendants from small-fruited wild progenitors for fleshy fruited species such as Solanum lycopersicum (tomato) and Prunus spp. (peach, cherry, plum, and apricot). The first fruit weight gene identified as a result of domestication and selection was the tomato FW2.2 gene. Members of the FW2.2 gene family in corn (Zea mays) have been named CNR (Cell Number Regulator) and two of them exert their effect on organ size by modulating cell number. Due to the critical roles of FW2.2/CNR genes in regulating cell number and organ size, this family provides an excellent source of candidates for fruit size genes in other domesticated species, such as those found in the Prunus genus. A total of 23 FW2.2/CNR family members were identified in the peach genome, spanning the eight Prunus chromosomes. Two of these CNRs were located within confidence intervals of major quantitative trait loci (QTL) previously discovered on linkage groups 2 and 6 in sweet cherry (Prunus avium), named PavCNR12 and PavCNR20, respectively. An analysis of haplotype, sequence, segregation and association with fruit size strongly supports a role of PavCNR12 in the sweet cherry linkage group 2 fruit size QTL, and this QTL is also likely present in sour cherry (P. cerasus). The finding that the increase in fleshy fruit size in both tomato and cherry associated with domestication may be due to changes in members of a common ancestral gene family supports the notion that similar phenotypic changes exhibited by independently domesticated taxa may have a common genetic basis.Electronic supplementary materialThe online version of this article (doi:10.1007/s11032-013-9872-6) contains supplementary material, which is available to authorized users.