Identification and characterization of microsatellite loci in the common fig (Ficus carica L.) and representative species of the genus Ficus

We developed microsatellites in fig (Ficus carica L.). A TC and TG‐enriched genomic library was screened, and after sequencing, primers were designed for 20 microsatellites. Eight primer pairs produced amplification products that were both interpretable and polymorphic in 14 fig cultivars and two French wild‐growing populations of F. carica (n₁ = 9 and n₂ = 10). Number of alleles per locus ranged from three to six. Except for one microsatellite locus, the observed heterozygosity was higher than the expected value. The F. carica microsatellites gave amplification products in 17 other Ficus species in 86% of the cases.     

Comparative Assessment of SSR and AFLP Markers for Evaluation of Genetic Diversity and Conservation of Fig, <Emphasis Type="Italic">Ficus carica</Emphasis> L., Genetic Resources in Tunisia

This study characterises the genetic variability of fig, Ficus carica L., using simple sequence repeat (SSR) and amplified fragment length polymorphism (AFLP) markers. It compares the efficiency and utility of the two techniques in detecting variation and establishing genetic relationships among Tunisian fig cultivars. Our results show that using both marker systems, the Tunisian fig germ plasm is characterised by having a large genetic diversity at the deoxyribonucleic acid level, as most of AFLP bands were detected and all SSR markers were polymorphic. In fact, 351 (342 polymorphic) and 57 (57 polymorphic) bands were detected using AFLP and SSR primers, respectively. SSR markers were the most polymorphic with an average polymorphic information content value of 0.94, while AFLP markers showed the highest effective multiplex ratio (56.9) and marker index (45.2). The effective marker index was recorded highest (4.19) for AFLP markers and lowest (0.70) for the SSR ones. Our results demonstrate that (1) independent as well as combined analyses of cluster analyses of SSR and AFLP fragments showed that cultivars are clustered independently from their geographical origin, horticultural classifications and tree sex; (2) the analysis of molecular variance allowed the partitioning of genetic variation within and among fig groups and showed greater variation within groups and (3) AFLP and SSR markers datasets showed positive correlation. This study suggests the SSR and AFLP markers are suitable for diversity analysis and cultivars fingerprinting. An understanding of the genetic diversity and population structure of F. carica in Tunisia can also provide insight into the conservation and management of this species.     

Strategies of leaf expansion in Ficus carica under semiarid conditions

Leaf area expansion, thickness and inclination, gas exchange parameters and relative chlorophyll content were analysed in field‐grown fig (Ficus carica L.) leaves over time, from emergence until after full leaf expansion (FLE). Ficus carica leaves showed a subtle change in shape during the early stages of development, and FLE was reached within ca. 30 days after emergence. Changes in leaf thickness and inclination after FLE demonstrated good adaptation to environmental conditions during summer in areas with a Mediterranean climate. Changes in gas exchange parameters and relative chlorophyll content showed that F. carica is a delayed‐greening species, reaching maximum values 20 days after FLE. Correlation analysis of datasets collected during leaf expansion, confirmed dependence among structural and functional traits in F. carica. Pn was directly correlated with stomatal conductance (Gs), transpiration (E), leaf area (LA) and relative chlorophyll content up to FLE. The effect of pruning on leaf expansion, a cultural technique commonly applied in this fruit tree, was also evaluated. Although leaf development in pruned branches gave a significantly higher relative leaf area growth rate (RGR_l) and higher LA than non‐pruned branches, no significant differences were found in other morphological and physiological traits, indicating no pruning effect on leaf development. All studied morphological and physiological characteristics indicate that F. carica is well adapted to semiarid conditions. The delayed greening strategy of this species is discussed.     

Esterase and acid phosphatase polymorphism in the fig tree (Ficus carica L.)

The genetics of two enzymatic loci, esterase (Est-D) and acid phosphatase (AcP-A), were studied by means of polyacrylamide gel electrophoresis in the fig tree (Ficus carica L.). Two codominant alleles are described at the Est-D locus and four codominant alleles at the AcP-A locus. Heterozygotes at the AcP-A locus have a hybrid band, thus showing that the AcP-A allozymes, are at least dimer molecules. Both loci are independent of the male sterility factor in F. carica. The polymorphism in four natural populations was investigated for both loci. A significant deficiency of heterozygotes was observed.     

Transferability and characterization of microsatellite markers in two Neotropical Ficus species

Microsatellite markers were transferred and characterized for two Neotropical fig tree species, Ficus citrifolia and Ficus eximia. Our study demonstrated that microsatellite markers developed from different subgenera of Ficus can be transferred to related species. In the present case, 12 of the 15 primer pairs tested (80%) were successfully transferred to both of the above species. Eleven loci were polymorphic when tested across 60 F. citrifolia and 60 F. eximia individuals. For F. citrifolia, there were 4 to 15 alleles per locus, whereas expected heterozygosities ranged from 0.31 to 0.91. In the case of F. eximia, this was 2 to 12 alleles per locus and expected heterozygosities from 0.42 to 0.87.     

Development of microsatellite markers in the common fig,Ficus carica L.

We present a new set of 15 polymorphic microsatellite primer sequences developed from Ficus carica L. The variability of specific microsatellite regions was assessed in wild population of figs from the northern Adriatic coast and all 15 primer pairs showed single‐locus amplification with a total of 65 alleles and an observed heterozygosity ranging from 0.285 to 0.863. The 15 new microsatellite loci represent a significant tool for population genetic structure studies and will be further used to investigate the origin and maintenance of genetic variation within and between populations of figs along the Adriatic coastal region.     

Some pollinators are more equal than others: Factors influencing pollen loads and seed set capacity of two actively and passively pollinating fig wasps

The nursery pollination system of fig trees (Ficus) results in the plants providing resources for pollinator fig wasp larvae as part of their male reproductive investment, with selection determining relative investment into pollinating wasps and the pollen they carry. The small size of Ficus pollen suggests that the quantities of pollen transported by individual wasps often limits male reproductive success. We assessed variation in fig wasp pollen loads and its influence on seed production in actively pollinated (Ficus montana) and passively pollinated (Ficus carica) dioecious fig trees.The ratios of number of male flowers on number of female flowers in a glasshouse-maintained F. montana population were highly variable. When fig wasps were introduced into receptive female figs, the resulting seed numbers were strongly linked to the numbers of pollinators that had been seeking access to pollen, relative to the number of anthers in their natal figs. In F. carica estimates of the amounts of pollen produced per fig and the quantities of pollen carried by emerging fig wasps suggest that less than 10% of the pollen is transported. Pollinators of F. carica that emerged earlier from figs carried more pollen, and also generated more seeds when introduced into receptive female figs.We show here that all pollinators are not equally valuable and producing more pollinators is not necessarily a good option in terms of Ficus male fitness. Previous results on F. montana figs showed that only around half of the flowers where pollinators lay eggs produced adult offspring. The amount of pollen collected by young female fig wasps may be a major determinant of their reproductive success.     

Few figs for frugivores: Riparian fig trees in Zimbabwe may not be a dry season keystone resource

Most plants flower and fruit at times of year when probabilities of pollination and seedling establishment are high. Fig trees (Ficus spp.) are often considered as keystone resources for vertebrate frugivores, in part because of year-round fig production. This unusual fruiting phenology results in the maintenance of fig wasp populations, but in seasonal environments this means fruiting occurs during periods when the chances of seedling establishment are low. Under these circumstances, selection is expected to favour any individuals that reduce or eliminate fruiting at these times. Here, we describe a large-scale survey of the extent of dry season fruiting by three riparian Ficus species in Gonarezhou National Park, Zimbabwe. Few trees of two monoecious species, F. sycomorus and F. abutilifolia, had figs, and most crops of F. sycomorus were far smaller than the trees were capable of producing. Large stands of the dioecious F. capreifolia were present, but fig densities were low and no mature female (seed containing) figs were recorded. Even though fig trees may have been the only species bearing fruit, the consequences of the low investment in reproduction by the three Ficus species were clear—there were too few figs for a landscape-scale keystone role.     

Coevolution of reproductive characteristics in three dioecious fig species and their pollinator wasps

This study investigates dioecious fig species using a pollinator introduction experiment. Our aims were to determine: (1) whether there was a significant difference in foundress distribution between sexes per fig species; (2) whether fig size and foundress number affect reproductive success of dioecious figs; and (3) who is the ‘controlling partner’ in the fig/pollinator mutualism. Three dioecious fig species: Ficus semicordata, Ficus hispida and Ficus tinctoria from Xishuangbanna, China, were selected for this experiment. We found that there was no significant difference of the foundress number in female and male figs of F. semicordata, F. hispida and F. tinctoria. Also, the foundress number did not depend on the fig diameter. The numbers and the proportions of fig seeds and female wasp offspring significantly increased with more foundresses; and fig seed number was significantly higher than female wasp offspring in F. semicordata and F. hispida, but not in F. tinctoria. Our results indicate that figs are generally the ‘controlling partner’ in fig-wasp mutualisms in species with large figs, but not with small figs. Compared with published studies of reproductive success in monoecious figs, the dioecious figs seem to be more efficient in producing both seeds and wasp offspring when there is a high number of foundress.     

Species‐diagnostic microsatellite loci for the fig wasp genus Pegoscapus

To obtain tools for the estimation of inbreeding and assignment of offspring to matrilines, we developed 13 microsatellite loci from the fig wasps that pollinate Ficus obtusifolia. Based on morphological studies, it was thought that a single species (Pegoscapus hoffmeyeri) pollinated this fig. However, our data revealed the presence of two coexisting cryptic species. Several diagnostic microsatellite markers may be used to distinguish these two cryptic species. The new microsatellites can be used across a wide range of fig‐pollinating wasp species for both evolutionary and population genetic studies.     

BREEDING SYSTEM IN FICUS CARICA,THE COMMON FIG. I. FLORAL DIVERSITY

Coevolution in Ficus carica (Moraceae) and the fig wasp (Blastophaga psenes, Agaonidae, Chalcidoidea) has resulted in a complex breeding system involving two tree morphs (Caprifig and Edible fig), three floral forms (long-styled female, short-styled female, and male flowers) and the insect pollinator. The two female floral forms have been reported to differ only in style length and stigma shape. In the present study, we demonstrate that the two female flowers differ from inception—short-styled flower primordia are smaller and exhibit significantly greater individual variation than do those of the long-styled flower, and the relative growth rate of each flower type differs. Mature forms exhibit disparity in style length, in stigma characteristics, and in degree of fusion of stylar lobes. Female flowers of both tree morphs are unisexual from inception. Male flowers of the Caprifig tree morph are initiated as hermaphrodites and gynoecium abortion occurs before megaspore mother cell stage. A single inflorescence therefore expresses two pathways to unisexuality. Hermaphrodite flower primordia were repeatedly found in the supposedly unisexual female syconium of the Edible fig tree morph. Based on its developmental morphology, Ficus carica appears to be of gynomonoecious ancestry.     

The Ficus erecta genome aids Ceratocystis canker resistance breeding in common fig (F. carica)

Ficus erecta, a wild relative of the common fig (F. carica), is a donor of Ceratocystis canker resistance in fig breeding programmes. Interspecific hybridization followed by recurrent backcrossing is an effective method to transfer the resistance trait from wild to cultivated fig. However, this process is time consuming and labour intensive for trees, especially for gynodioecious plants such as fig. In this study, genome resources were developed for F. erecta to facilitate fig breeding programmes. The genome sequence of F. erecta was determined using single‐molecule real‐time sequencing technology. The resultant assembly spanned 331.6 Mb with 538 contigs and an N50 length of 1.9 Mb, from which 51 806 high‐confidence genes were predicted. Pseudomolecule sequences corresponding to the chromosomes of F. erecta were established with a genetic map based on single nucleotide polymorphisms from double‐digest restriction‐site‐associated DNA sequencing. Subsequent linkage analysis and whole‐genome resequencing identified a candidate gene for the Ceratocystis canker resistance trait. Genome‐wide genotyping analysis enabled the selection of female lines that possessed resistance and effective elimination of the donor genome from the progeny. The genome resources provided in this study will accelerate and enhance disease‐resistance breeding programmes in fig.     

Yeasts of Nikitsky Botanical Garden plants

Abundance and taxonomic structure of yeast communities on the surface and in the tissues of various plants of the Nikitsky Botanical Garden was studied. A total of 22 yeast species were isolated, including rare and new species. Yeast numbers on the studied plant substrates were varied within a broad range (8 × 10²?2.5 × 10⁷ CFU/g), reaching the maximum in Verbascum thapsus flowers, on the surface and inside the fruits of Rubus sp. and Ficus carica. Epiphytic and endophytic yeast communities of Ficus carica fruits were studied in dynamics, from fruit formation until their complete maturation and senescence. Specific properties of the yeast communities of the Nikitsky Botanical Garden plants and the features of the yeast communities from fig fruits are discussed in the paper.     

Occurrence of crown gall disease on Ficus benjamina in Fars and Isfahan provinces of Iran

Ficus benjamina, commonly known as weeping fig, Benjamin’s fig or Ficus tree is a species of flowering plant in the family of Moraceae. It is native to south and south-east Asia and Australia. Crown gall tumours were collected from branches of one-year-old weeping fig (F. benjamina L.) trees. A total of 50 strains of Agrobacterium tumefaciens were isolated from diseased Ficus plants and their morphological, molecular and biochemical characteristics were studied; pathogenicity tests on tomato, F. benjamina and Bryophyllum daigremontianum were also conducted. Based on the biochemical characteristics, pathogenicity test and PCR amplification of 730?bp fragment using VCR\VCF primers, the tested bacterial strains were identified as A. tumefaciens. This is the first report of crown gall on F. benjamina in Isfahan and Fars provinces of Iran.     

Development and characterization of microsatellite markers for a fig‐pollinating wasp (Ceratosolen sp. 1) of Ficus septica

For an undescribed fig‐pollinating wasp (Ceratosolen sp. 1) of Ficus septica, we isolated 15 polymorphic microsatellite markers from a genomic library partially enriched for GATA and CAG repeats. Polymorphism of these loci was evaluated by genotyping 40 female individuals collected from different fruits of host trees in southern Taiwan. The number of alleles per locus ranged from three to 15 and the observed heterozygosity of each locus ranged from 0.100 to 0.775. These loci would be suitable for further studies concerning population genetics, hybridization and sex ratio adjustment of the coexisting fig‐pollinating wasps.     

THE STABILITY OF THE SYMBIOSIS BETWEEN DIOECIOUS FIGS AND THEIR POLLINATORS: A STUDY OF FICUS CARICA L. AND BLASTOPHAGA PSENES L.

Each Ficus species depends on a specific mutualistic wasp for pollination. The wasp breeds on the fig, each larva destroying a female flower. It is, however, not known why the wasps have not evolved the ability to use all female flowers. In “dioecious” figs, the wasp can only breed in the female flowers of the “male” trees, so that pollination of a female tree is always lethal. The wasps should therefore be selected to avoid female trees. Field data is presented showing that the fruiting phenology of the dioecious fig Ficus carica is such that this selection does not occur: syconia are not receptive at the same time on “male” and female trees. Most wasps are forced to emerge from the syconia of “male” trees at a time when they will not be able to reproduce, whether they avoid female trees or not. This aspect of the life cycle of the wasp, although noticed, has been obscured in most previous studies. It is shown that the fruiting phenology of Ficus carica, which stabilizes the symbiosis, is the result of short-term selective pressures on the male function of the trees. Such selective pressures suggest a possible pathway from monoecy to dioecy in Ficus under seasonal climates.     

Development of 17 microsatellite markers for Ceratosolen constrictus, the pollinating fig wasp of Ficus fistulosa

The obligate mutualism between figs (Ficus) and fig pollinating wasps (Agaonidae) is regarded as a classic example of mutualism. Seventeen polymorphic microsatellite loci were developed for Ceratosolen constrictus, the pollinating wasp of the dioecious fig Ficus fistulosa. The number of alleles per locus ranged from two to 15 and the observed and expected heterozygosities ranged from 0.040 to 0.846 and from 0.040 to 0.916, respectively. These microsatellite loci offer a powerful tool for evolutionary and population genetic studies in C. constrictus, and gene flow of F. fistulosa.     

Development and characterization of microsatellite markers for two dioecious Ficus species

Microsatellite markers for Ficus montana and Ficus septica were developed using genomic libraries enriched for di‐, tri‐ and tetranucleotide repeats. The subsets of five and three best scorable primer pairs were characterized on 24 F. montana and 36 F. septica individuals, respectively. For F. montana, loci showed five to 14 alleles per locus and expected heterozygosities ranged between 0.23 and 0.87. For F. septica, loci showed three to five alleles per locus and expected heterozygosities ranged between 0.36 and 0.49. Four primer pairs (two from each subset) cross‐amplified in the other species, indicating transportability of the markers within the genus Ficus.     

Phenological Adaptations in Ficus tikoua Exhibit Convergence with Unrelated Extra-Tropical Fig Trees

Flowering phenology is central to the ecology and evolution of most flowering plants. In highly-specific nursery pollination systems, such as that involving fig trees (Ficus species) and fig wasps (Agaonidae), any mismatch in timing has serious consequences because the plants must balance seed production with maintenance of their pollinator populations. Most fig trees are found in tropical or subtropical habitats, but the dioecious Chinese Ficus tikoua has a more northerly distribution. We monitored how its fruiting phenology has adapted in response to a highly seasonal environment. Male trees (where fig wasps reproduce) had one to three crops annually, whereas many seed-producing female trees produced only one fig crop. The timing of release of Ceratosolen fig wasps from male figs in late May and June was synchronized with the presence of receptive figs on female trees, at a time when there were few receptive figs on male trees, thereby ensuring seed set while allowing remnant pollinator populations to persist. F. tikoua phenology has converged with those of other (unrelated) northern Ficus species, but there are differences. Unlike F. carica in Europe, all F. tikoua male figs contain male flowers, and unlike F. pumila in China, but like F. carica, it is the second annual generation of adult wasps that pollinate female figs. The phenologies of all three temperate fig trees generate annual bottlenecks in the size of pollinator populations and for female F. tikoua also a shortage of fig wasps that results in many figs failing to be pollinated.