Variation of cytoplasmic genome offers tremendous opportunities to evaluate the level as well the... more Variation of cytoplasmic genome offers tremendous opportunities to evaluate the level as well the structuration of molecular polymorphism in several fruit trees. The purpose of the current study is to evaluate the molecular diversity of atpB-rbcL spacer sequences of chloroplast DNA of Ficus carica cultivars. The atpB-rbcL spacer was sequenced for thirty-one fig cultivars. Sequences were submitted to NCBI GenBank and analyzed with different statistical methods. Hundred seventeen in silico enzymes were tested and only 46 had digested at the atpB-rbcL intergenic spacer. These have generated polymorphic restriction profiles. A total of 93 restriction sites were detected with 92 that were polymorphic. A genetic distance shows the presence of a large diversity between figs. The topology of the neighbor-joining dendrogram and the principal components analysis demonstrates no distinction between female trees and pollinators. The results suggest the existence of a common genetic basis between the two types of figs and show that the PCR-RFLP technique is a powerful technique and informative approach to explore cytoplasmic polymorphism of Tunisian fig trees. The expansion of this study to other regions of the genome and a higher number of cultivars would allow obtaining new molecular markers that could better appreciate the structure of the molecular diversity and organization within the local fig germplasm.
Abstract The genus Citrus L. is among the most important fruit trees in the world. In this report... more Abstract The genus Citrus L. is among the most important fruit trees in the world. In this report, cytoplasmic polymorphism of twenty seven Tunisian Citrus cultivars was explored using the chloroplast trn L- trn F intergenic spacer. Chloroplast sequences showed variation in length and nucleotide content. Haplotype and nucleotide diversity showed low variations. Molecular phylogenetic tree identifies Citrus maternal origins and demonstrates two major groups distinguishing between mandarin and pummelo groups. The trn L- trn F intergenic spacer showed one copy of pseudogene of the original trn F gene in 27 Citrus species at position 275 bp with a size varying from 49 to 63 bp. The anticodon domain was identified as the most conserved element, but one transversion (T−>C) was found in the D-domain. Meanwhile, one transversion (T−>A) and one transition (T−>G) were found in the T-domain. Neutrality tests (Tajima, Fu & Li and Fu) which revealed positive and non-significant values and Pi and θ W assume a neutral model of evolution and advocated a constant population size. The study demonstrates the resolving power of trn L- trn F sequence data to prove both pummelo and mandarin gene pool’s contribution in the development of Tunisian secondary species and inferring their genetic and phylogenetic relationships.
Populations of oak cork (Quercus suber L.) originated from different areas in Tunisia were analys... more Populations of oak cork (Quercus suber L.) originated from different areas in Tunisia were analysed based on morphological characters to assess the overall degree of phenotypic variability, to detect similarities between the genotypes and to evaluate significant forest features. One-way ANOVA analysis shows a significant difference between oak cork populations and demonstrates that parameters measured on leaves show an important degree of variability and permit to discriminate oak cork individuals. Vegetative variables are leaf length, leaf width, petioles length, number of leaf veins, petioles width, spines number, leaf area, length nipples, diameter nipples, weight nipples, and height trees. Diameter trees were scored and subjected to multivariate analysis. Results showed a considerable diversity among local germoplasme of oak cork. Principal component analysis (PCA) revealed that the characters related to the length and width of the sheets and the nipples accounted for a large proportion of the observed variability. Cluster analysis showed a typically continuous phenotypic diversity among oak cork accessions, and little associations between accessions from same geographic origin. Also, some heterogeneity within accessions that received the same denomination was evidenced. The variability observed between different populations is attached to phenotypic characters which depend primarily on two factors, gene and environment.
Here, we report the nucleotide variation in two non-coding regions of the chloroplast DNA (cpDNA)... more Here, we report the nucleotide variation in two non-coding regions of the chloroplast DNA (cpDNA) to construct a possible evolutionary scenario in Ficus carica L. Our results suggest the occurrence of haplotypic and nucleotide diversity with a large variation level of chloroplast non-coding regions. Furthermore, our results demonstrated an explicit rejection of the null hypothesis that within F. carica the intron trnL and the spacer trnL-trnF evolved under a strictly neutral model of molecular evolution. Although, recent population expansion could serve as one alternative explanation for the detected excess of singleton, our results imply a positive selection and the genetic hitchhiking effect is unlikely. Parameters performed supported scenario of sweep selection and recent expansion of F. carica across Tunisia. Our results indicate that both positive selection and demographic histories have jointly contributed to the observed patterns of nucleotide diversity and haplotypes structure. Based on the results, we characterize the fig resources and provide several suggestions for effective conservation and improvement programs.
Self-incompatibility (SI) to self-compatibility (SC) transition is one of the most frequent and p... more Self-incompatibility (SI) to self-compatibility (SC) transition is one of the most frequent and prevalent evolutionary shifts in flowering plants. Prunus L. (Rosaceae) is a genus of over 200 species most of which exhibit a Gametophytic SI system. Peach [Prunus persica (L.) Batsch; 2n = 16] is one of the few exceptions in the genus known to be a fully selfcompatible species. However, the evolutionary process of the complete and irreversible loss of SI in peach is not well understood and, in order to fill that gap, in this study 24 peach accessions were analyzed. Pollen tube growth was controlled in self-pollinated flowers to verify their self-compatible phenotypes. The linkage disequilibrium association between alleles at the S-locus and linked markers at the end of the sixth linkage group was not significant (P > 0.05), except with the closest markers suggesting the absence of a signature of negative frequency dependent selection at the S-locus. Analysis of SFB1 and SFB2 protein sequences allowed identifying the absence of some variable and hypervariable domains and the presence of additional α-helices at the C-termini. Molecular and evolutionary analysis of SFB nucleotide sequences showed a signature of purifying selection in SFB2, while the SFB1 seemed to evolve neutrally. Thus, our results show that the SFB2 allele diversified after P. persica and P. dulcis (almond) divergence, a period which is characterized by an important bottleneck, while SFB1 diversified at a transition time between the bottleneck and population expansion.
We used simple sequence repeat markers and 25 morphological characters to characterize 18 Tunisia... more We used simple sequence repeat markers and 25 morphological characters to characterize 18 Tunisian fig (Ficus carica L.) cultivars. Morphological traits suggested a high level of variation in the germplasm. Principal component analysis (PCA) differentiated the studied cultivars. In the derived dendrogram the cultivars clustered independently of their geographical origin and sex of trees. Simple sequence repeat (SSR) markers were used to compare genetic polymorphism with the observed phenotypic variation. Using six microsatellite primers, 39 alleles and 59 genotypes were identified. The high values of polymorphism information content (PIC), ranging from 0.67 to 0.85, confirmed the effectiveness of microsatellite analysis for determining molecular polymorphism and characterizing the studied cultivars. Multilocus genotyping unambiguously distinguished all the cultivars. The ability of each type of feature to differentiate cultivars of this crop is discussed.
Fig, Ficus carica L., is a useful genetic resource for commercial cultivation. In this study, RAP... more Fig, Ficus carica L., is a useful genetic resource for commercial cultivation. In this study, RAPD (60), ISSR (48), RAMPO (63), and SSR (34) markers were compared to detect polymorphism and to establish genetic relationships among Tunisian fig tree cultivars. The statistical procedures conducted on the combined data show considerable genetic diversity, and the tested markers discriminated all fig genotypes studied. The identification key established on the basis of SSR permitted the unambiguous discrimination of cultivars and confirmed the reliability of SSR for fingerprinting fig genotypes. The study findings are discussed in relation to the establishment of a national reference collection that will aid in the conservation of Tunisian fig resources.
Sequences of the trnL-trnF spacer and combined trnL-trnF region in chloroplast DNA of cork oak (Q... more Sequences of the trnL-trnF spacer and combined trnL-trnF region in chloroplast DNA of cork oak (Quercus suber L.) were analyzed to detect polymorphisms and to elucidate molecular evolution and demographic history. The aligned sequences varied in length and nucleotide composition. The overall ratio of transition/transversion (ti/ tv) of 0.724 for the intergenic spacer and 0.258 for the pooled sequences were estimated, and indicated that transversions are more frequent than transitions. The molecular evolution and demographic history of Q. suber were investigated. Neutrality tests (Tajima's D and Fu and Li) ruled out the null hypothesis of a strictly neutral model, and Fu's Fs and Ramos-Onsins and Rozas' R2 confirmed the recent expansion of cork oak trees, validating its persistency in North Africa since the last glaciation during the Quaternary. The observed uni-modal mismatch distribution and the Harpending's raggedness index confirmed the demographic history model for cork oak. A phylogenetic dendrogram showed that the distribution of Q. suber trees occurs independently of geographical origin, the relief of the population site, and the bioclimatic stages. The molecular history and cytoplasmic diversity suggest that in situ and ex situ conservation strategies can be recommended for preserving landscape value and facing predictable future climatic changes.
Sequence alignment of all Aurantioideae accessions for the eight chloroplast regions. (XLSX 3440Â... more Sequence alignment of all Aurantioideae accessions for the eight chloroplast regions. (XLSX 3440Â kb)
Example of diagnostic SNP mining in the region rps4-trnT in the position 49301 distinguishing the... more Example of diagnostic SNP mining in the region rps4-trnT in the position 49301 distinguishing the accessions of clade Q (A) from all other Aurantioideae accessions (G). (XLSX 38Â kb)
Cytoplasmic chloroplast DNA was explored to establish genetic relationships among Ficus carica cu... more Cytoplasmic chloroplast DNA was explored to establish genetic relationships among Ficus carica cultivars and elucidate the molecular evolution of the species. The results suggest the occurrence of haplotype and nucleotide diversity. Conserved group I intron sequence motifs were detected and showed a common secondary structure, despite the presence of some mutations on their sequences. The neighbor-joining dendrogram showed a continuous diversity that characterizes local resources. The maximum parsimony tree, with an RI index of 0.507, indicated minimal homoplasy within the data set. Furthermore, our results demonstrate that the trnL intron is the seat of numerous substitutions. Herein, new insight on the mechanism involved in the evolution of the trnL intron in the fig is presented. From the study, it appears that there is an explicit rejection of the null hypothesis in F. carica. A scenario of positive selection and recent expansion of F. carica genotypes across Tunisia seems to be retained.
Mitochondrial DNA was explored to study phylogeography of the nematode parasite Heligmosomum mixt... more Mitochondrial DNA was explored to study phylogeography of the nematode parasite Heligmosomum mixtum and elucidate molecular evolution pattern of cytochrome b gene. The size of cyt b gene ranged from 511 bp to 591 bp and the average of GC contents was 28.9%. The overall transition/transversion ratio R was 5.773 indicating that the transitions are more frequent than transversion. The aligned sequences allowed identifying 54 mtDNA haplotypes among the 119 examined individuals. The genetic divergence registered among the populations of H. mixtum was low (0.3% to 1.5%). Neighbor-joining and maximum Likelihood trees evidenced a huge polytomy and unstructured phylogeographic pattern among the studied populations. The demographic analyses tend to evidence a recent and rapid expansion of H. mixtum. Our results imply a positive selection and the genetic hitchhiking effect is unlikely. Parameters performed supported scenario of sweep selection and recent expansion of H.mixtum populations. Both positive selection and demographic histories have jointly contributed to the observed patterns of nucleotide diversity and haplotypes structure. The comparison of the phylogeographical pattern of H. mixtum with the one of its most common rodent host M. glareolus, confirmed a strong incongruence between the two species. These results strongly suggest that the parasite would not be specific to M. glareolus and that it would switch easily from one rodent species to another. The mitochondrial diversity seems to be unstructured with any biogeographic repartition of the variability and that the genetic structure of H. mixtum is probably associated with weak host specificity.
We used simple sequence repeat markers and 25 morphological characters to characterize 18 Tunisia... more We used simple sequence repeat markers and 25 morphological characters to characterize 18 Tunisian fig (Ficus carica L.) cultivars. Morphological traits suggested a high level of variation in the germplasm. Principal component analysis (PCA) differentiated the studied cultivars. In the derived dendrogram the cultivars clustered independently of their geographical origin and sex of trees. Simple sequence repeat (SSR) markers were used to compare genetic polymorphism with the observed phenotypic variation. Using six microsatellite primers, 39 alleles and 59 genotypes were identified. The high values of polymorphism information content (PIC), ranging from 0.67 to 0.85, confirmed the effectiveness of microsatellite analysis for determining molecular polymorphism and characterizing the studied cultivars. Multilocus genotyping unambiguously distinguished all the cultivars. The ability of each type of feature to differentiate cultivars of this crop is discussed.
Abstract Prunus L. (Rosaceae), a genus of over 230 species, exhibits gametophytic self-incompatib... more Abstract Prunus L. (Rosaceae), a genus of over 230 species, exhibits gametophytic self-incompatibility system (GSI). In this study, we explored the patterns of variability in Plum genotypes carrying different reproductive systems, using 36 microsatellite markers (SSRs) and the S-locus. The analysis of genetic diversity showed a rich genetic variability of the studied genotypes. Linkage Disequilibrium decayed rapidly in analyzed plums reaching the significant value (r² = 0.1) at 7.5 cM. Also, we examined the patterns of variability at the end of the sixth linkage group to emphasize the effect of the S-locus on the surrounding region. The genetic diversity in the genomic neighborhood of the S-locus is related to the negative frequency dependent selection (NFDS) which can extend the high polymorphism at the selected locus to closely linked neutral sites. We conducted a drought stress on Tunisian plum to test their response. The analysis of five morphological parameters tested under drought conditions allowed selecting five plum genotypes (one hexploid and four diploid) characterized by their important tolerance to drought stress. These genotypes may be selected as important rootstock for varietal improvement.
Variation of cytoplasmic genome offers tremendous opportunities to evaluate the level as well the... more Variation of cytoplasmic genome offers tremendous opportunities to evaluate the level as well the structuration of molecular polymorphism in several fruit trees. The purpose of the current study is to evaluate the molecular diversity of atpB-rbcL spacer sequences of chloroplast DNA of Ficus carica cultivars. The atpB-rbcL spacer was sequenced for thirty-one fig cultivars. Sequences were submitted to NCBI GenBank and analyzed with different statistical methods. Hundred seventeen in silico enzymes were tested and only 46 had digested at the atpB-rbcL intergenic spacer. These have generated polymorphic restriction profiles. A total of 93 restriction sites were detected with 92 that were polymorphic. A genetic distance shows the presence of a large diversity between figs. The topology of the neighbor-joining dendrogram and the principal components analysis demonstrates no distinction between female trees and pollinators. The results suggest the existence of a common genetic basis between the two types of figs and show that the PCR-RFLP technique is a powerful technique and informative approach to explore cytoplasmic polymorphism of Tunisian fig trees. The expansion of this study to other regions of the genome and a higher number of cultivars would allow obtaining new molecular markers that could better appreciate the structure of the molecular diversity and organization within the local fig germplasm.
Abstract The genus Citrus L. is among the most important fruit trees in the world. In this report... more Abstract The genus Citrus L. is among the most important fruit trees in the world. In this report, cytoplasmic polymorphism of twenty seven Tunisian Citrus cultivars was explored using the chloroplast trn L- trn F intergenic spacer. Chloroplast sequences showed variation in length and nucleotide content. Haplotype and nucleotide diversity showed low variations. Molecular phylogenetic tree identifies Citrus maternal origins and demonstrates two major groups distinguishing between mandarin and pummelo groups. The trn L- trn F intergenic spacer showed one copy of pseudogene of the original trn F gene in 27 Citrus species at position 275 bp with a size varying from 49 to 63 bp. The anticodon domain was identified as the most conserved element, but one transversion (T−>C) was found in the D-domain. Meanwhile, one transversion (T−>A) and one transition (T−>G) were found in the T-domain. Neutrality tests (Tajima, Fu & Li and Fu) which revealed positive and non-significant values and Pi and θ W assume a neutral model of evolution and advocated a constant population size. The study demonstrates the resolving power of trn L- trn F sequence data to prove both pummelo and mandarin gene pool’s contribution in the development of Tunisian secondary species and inferring their genetic and phylogenetic relationships.
Populations of oak cork (Quercus suber L.) originated from different areas in Tunisia were analys... more Populations of oak cork (Quercus suber L.) originated from different areas in Tunisia were analysed based on morphological characters to assess the overall degree of phenotypic variability, to detect similarities between the genotypes and to evaluate significant forest features. One-way ANOVA analysis shows a significant difference between oak cork populations and demonstrates that parameters measured on leaves show an important degree of variability and permit to discriminate oak cork individuals. Vegetative variables are leaf length, leaf width, petioles length, number of leaf veins, petioles width, spines number, leaf area, length nipples, diameter nipples, weight nipples, and height trees. Diameter trees were scored and subjected to multivariate analysis. Results showed a considerable diversity among local germoplasme of oak cork. Principal component analysis (PCA) revealed that the characters related to the length and width of the sheets and the nipples accounted for a large proportion of the observed variability. Cluster analysis showed a typically continuous phenotypic diversity among oak cork accessions, and little associations between accessions from same geographic origin. Also, some heterogeneity within accessions that received the same denomination was evidenced. The variability observed between different populations is attached to phenotypic characters which depend primarily on two factors, gene and environment.
Here, we report the nucleotide variation in two non-coding regions of the chloroplast DNA (cpDNA)... more Here, we report the nucleotide variation in two non-coding regions of the chloroplast DNA (cpDNA) to construct a possible evolutionary scenario in Ficus carica L. Our results suggest the occurrence of haplotypic and nucleotide diversity with a large variation level of chloroplast non-coding regions. Furthermore, our results demonstrated an explicit rejection of the null hypothesis that within F. carica the intron trnL and the spacer trnL-trnF evolved under a strictly neutral model of molecular evolution. Although, recent population expansion could serve as one alternative explanation for the detected excess of singleton, our results imply a positive selection and the genetic hitchhiking effect is unlikely. Parameters performed supported scenario of sweep selection and recent expansion of F. carica across Tunisia. Our results indicate that both positive selection and demographic histories have jointly contributed to the observed patterns of nucleotide diversity and haplotypes structure. Based on the results, we characterize the fig resources and provide several suggestions for effective conservation and improvement programs.
Self-incompatibility (SI) to self-compatibility (SC) transition is one of the most frequent and p... more Self-incompatibility (SI) to self-compatibility (SC) transition is one of the most frequent and prevalent evolutionary shifts in flowering plants. Prunus L. (Rosaceae) is a genus of over 200 species most of which exhibit a Gametophytic SI system. Peach [Prunus persica (L.) Batsch; 2n = 16] is one of the few exceptions in the genus known to be a fully selfcompatible species. However, the evolutionary process of the complete and irreversible loss of SI in peach is not well understood and, in order to fill that gap, in this study 24 peach accessions were analyzed. Pollen tube growth was controlled in self-pollinated flowers to verify their self-compatible phenotypes. The linkage disequilibrium association between alleles at the S-locus and linked markers at the end of the sixth linkage group was not significant (P > 0.05), except with the closest markers suggesting the absence of a signature of negative frequency dependent selection at the S-locus. Analysis of SFB1 and SFB2 protein sequences allowed identifying the absence of some variable and hypervariable domains and the presence of additional α-helices at the C-termini. Molecular and evolutionary analysis of SFB nucleotide sequences showed a signature of purifying selection in SFB2, while the SFB1 seemed to evolve neutrally. Thus, our results show that the SFB2 allele diversified after P. persica and P. dulcis (almond) divergence, a period which is characterized by an important bottleneck, while SFB1 diversified at a transition time between the bottleneck and population expansion.
We used simple sequence repeat markers and 25 morphological characters to characterize 18 Tunisia... more We used simple sequence repeat markers and 25 morphological characters to characterize 18 Tunisian fig (Ficus carica L.) cultivars. Morphological traits suggested a high level of variation in the germplasm. Principal component analysis (PCA) differentiated the studied cultivars. In the derived dendrogram the cultivars clustered independently of their geographical origin and sex of trees. Simple sequence repeat (SSR) markers were used to compare genetic polymorphism with the observed phenotypic variation. Using six microsatellite primers, 39 alleles and 59 genotypes were identified. The high values of polymorphism information content (PIC), ranging from 0.67 to 0.85, confirmed the effectiveness of microsatellite analysis for determining molecular polymorphism and characterizing the studied cultivars. Multilocus genotyping unambiguously distinguished all the cultivars. The ability of each type of feature to differentiate cultivars of this crop is discussed.
Fig, Ficus carica L., is a useful genetic resource for commercial cultivation. In this study, RAP... more Fig, Ficus carica L., is a useful genetic resource for commercial cultivation. In this study, RAPD (60), ISSR (48), RAMPO (63), and SSR (34) markers were compared to detect polymorphism and to establish genetic relationships among Tunisian fig tree cultivars. The statistical procedures conducted on the combined data show considerable genetic diversity, and the tested markers discriminated all fig genotypes studied. The identification key established on the basis of SSR permitted the unambiguous discrimination of cultivars and confirmed the reliability of SSR for fingerprinting fig genotypes. The study findings are discussed in relation to the establishment of a national reference collection that will aid in the conservation of Tunisian fig resources.
Sequences of the trnL-trnF spacer and combined trnL-trnF region in chloroplast DNA of cork oak (Q... more Sequences of the trnL-trnF spacer and combined trnL-trnF region in chloroplast DNA of cork oak (Quercus suber L.) were analyzed to detect polymorphisms and to elucidate molecular evolution and demographic history. The aligned sequences varied in length and nucleotide composition. The overall ratio of transition/transversion (ti/ tv) of 0.724 for the intergenic spacer and 0.258 for the pooled sequences were estimated, and indicated that transversions are more frequent than transitions. The molecular evolution and demographic history of Q. suber were investigated. Neutrality tests (Tajima's D and Fu and Li) ruled out the null hypothesis of a strictly neutral model, and Fu's Fs and Ramos-Onsins and Rozas' R2 confirmed the recent expansion of cork oak trees, validating its persistency in North Africa since the last glaciation during the Quaternary. The observed uni-modal mismatch distribution and the Harpending's raggedness index confirmed the demographic history model for cork oak. A phylogenetic dendrogram showed that the distribution of Q. suber trees occurs independently of geographical origin, the relief of the population site, and the bioclimatic stages. The molecular history and cytoplasmic diversity suggest that in situ and ex situ conservation strategies can be recommended for preserving landscape value and facing predictable future climatic changes.
Sequence alignment of all Aurantioideae accessions for the eight chloroplast regions. (XLSX 3440Â... more Sequence alignment of all Aurantioideae accessions for the eight chloroplast regions. (XLSX 3440Â kb)
Example of diagnostic SNP mining in the region rps4-trnT in the position 49301 distinguishing the... more Example of diagnostic SNP mining in the region rps4-trnT in the position 49301 distinguishing the accessions of clade Q (A) from all other Aurantioideae accessions (G). (XLSX 38Â kb)
Cytoplasmic chloroplast DNA was explored to establish genetic relationships among Ficus carica cu... more Cytoplasmic chloroplast DNA was explored to establish genetic relationships among Ficus carica cultivars and elucidate the molecular evolution of the species. The results suggest the occurrence of haplotype and nucleotide diversity. Conserved group I intron sequence motifs were detected and showed a common secondary structure, despite the presence of some mutations on their sequences. The neighbor-joining dendrogram showed a continuous diversity that characterizes local resources. The maximum parsimony tree, with an RI index of 0.507, indicated minimal homoplasy within the data set. Furthermore, our results demonstrate that the trnL intron is the seat of numerous substitutions. Herein, new insight on the mechanism involved in the evolution of the trnL intron in the fig is presented. From the study, it appears that there is an explicit rejection of the null hypothesis in F. carica. A scenario of positive selection and recent expansion of F. carica genotypes across Tunisia seems to be retained.
Mitochondrial DNA was explored to study phylogeography of the nematode parasite Heligmosomum mixt... more Mitochondrial DNA was explored to study phylogeography of the nematode parasite Heligmosomum mixtum and elucidate molecular evolution pattern of cytochrome b gene. The size of cyt b gene ranged from 511 bp to 591 bp and the average of GC contents was 28.9%. The overall transition/transversion ratio R was 5.773 indicating that the transitions are more frequent than transversion. The aligned sequences allowed identifying 54 mtDNA haplotypes among the 119 examined individuals. The genetic divergence registered among the populations of H. mixtum was low (0.3% to 1.5%). Neighbor-joining and maximum Likelihood trees evidenced a huge polytomy and unstructured phylogeographic pattern among the studied populations. The demographic analyses tend to evidence a recent and rapid expansion of H. mixtum. Our results imply a positive selection and the genetic hitchhiking effect is unlikely. Parameters performed supported scenario of sweep selection and recent expansion of H.mixtum populations. Both positive selection and demographic histories have jointly contributed to the observed patterns of nucleotide diversity and haplotypes structure. The comparison of the phylogeographical pattern of H. mixtum with the one of its most common rodent host M. glareolus, confirmed a strong incongruence between the two species. These results strongly suggest that the parasite would not be specific to M. glareolus and that it would switch easily from one rodent species to another. The mitochondrial diversity seems to be unstructured with any biogeographic repartition of the variability and that the genetic structure of H. mixtum is probably associated with weak host specificity.
We used simple sequence repeat markers and 25 morphological characters to characterize 18 Tunisia... more We used simple sequence repeat markers and 25 morphological characters to characterize 18 Tunisian fig (Ficus carica L.) cultivars. Morphological traits suggested a high level of variation in the germplasm. Principal component analysis (PCA) differentiated the studied cultivars. In the derived dendrogram the cultivars clustered independently of their geographical origin and sex of trees. Simple sequence repeat (SSR) markers were used to compare genetic polymorphism with the observed phenotypic variation. Using six microsatellite primers, 39 alleles and 59 genotypes were identified. The high values of polymorphism information content (PIC), ranging from 0.67 to 0.85, confirmed the effectiveness of microsatellite analysis for determining molecular polymorphism and characterizing the studied cultivars. Multilocus genotyping unambiguously distinguished all the cultivars. The ability of each type of feature to differentiate cultivars of this crop is discussed.
Abstract Prunus L. (Rosaceae), a genus of over 230 species, exhibits gametophytic self-incompatib... more Abstract Prunus L. (Rosaceae), a genus of over 230 species, exhibits gametophytic self-incompatibility system (GSI). In this study, we explored the patterns of variability in Plum genotypes carrying different reproductive systems, using 36 microsatellite markers (SSRs) and the S-locus. The analysis of genetic diversity showed a rich genetic variability of the studied genotypes. Linkage Disequilibrium decayed rapidly in analyzed plums reaching the significant value (r² = 0.1) at 7.5 cM. Also, we examined the patterns of variability at the end of the sixth linkage group to emphasize the effect of the S-locus on the surrounding region. The genetic diversity in the genomic neighborhood of the S-locus is related to the negative frequency dependent selection (NFDS) which can extend the high polymorphism at the selected locus to closely linked neutral sites. We conducted a drought stress on Tunisian plum to test their response. The analysis of five morphological parameters tested under drought conditions allowed selecting five plum genotypes (one hexploid and four diploid) characterized by their important tolerance to drought stress. These genotypes may be selected as important rootstock for varietal improvement.
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Papers by Ghada Baraket