Mustapha Rouaissi

Genetic diversity of nine faba bean (Vicia faba L.) populations revealed by isozyme markers

Seven isozyme systems (Sod, 6-Pgd, Me, Est, Skdh, Fdh and Gdh) representing nine loci were used to study the genetic diversity of nine faba bean populations. Seven loci revealed polymorphic bands and showed the same quaternary structure as that found in several species. They revealed a high number of phenotypes. Indeed, from 3 to 9 phenotypes per locus were investigated in this study. The percentage of polymorphic loci (P = 59.3 %) was higher than that mentioned in the autogamous species (P = 20.3 %) and less than the optimum (P=96 %) indicated for allogamous plants. Total genetic diversity (HT) and within population genetic diversity (HS) were estimated with the isozyme markers. The contribution of among population genetic diversity (DST) to total genetic diversity was 22%. Enzyme markers pointed out an average inbreeding level for whole population (FIT) and within population (FIS). Within population genetic diversity represents 78% of total diversity. Intra-population genetic diversity (HS = 0.206) was ranged with the respect of allogamous species and was clearly higher than that of among population genetic diversity (DST = 0.057) indicating an out-crossing predominance in the studied populations. The expected heterozygosity was higher than that observed heterozygosity at the allogamous species was confirmed in this study. Although, the mean estimated gene flow was less than 1(Nm=0.814), the dendrogram based on Nei’s genetic distance of the 9 populations using UPGMA method showed some genetic drift between populations.

Genetic diversity of faba bean ( Vicia faba L.) populations revealed by sequence specific amplified polymorphism (SSAP) markers

This study used sequence specifc amplifcation polymorphism (SSAP) markers to investigate the genetic diversity and population genetic structure of nine Tunisian Vicia faba populations belonging to the minor and major faba bean’s sub-species. Three primers were used (PDR1, Tps19 and Tvf4 ) in this study. These primers gave good SSAP marker profiles, high number of bands obtained per gel and a high percentage of polymorphic bands as confirmed in a previous study. Indeed, these primers provided a total of 173 amplified bands, with 123 of them being polymorphic. Shannon indexes ranges from 0.166 to 0.248 with an average of 0.207. The genetic diversity within population of 0.743 was clearly higher than that of among population genetic diversity (Dst = 0.138), indicating an out-crossing predominance in the studied populations. The Dst value showed that 15.6% of the total genetic variation resided among populations, a little lower than that of out-crossing species. The dendrogram grouping the populations by unweighted pair-group method with arithmetic averages (UPGMA) method revealed three main clusters. The local major faba bean ‘Batata’ was the most divergent population and was separated from other population.

Genetic diversity assessed by SSR markers and chemotyping of Fusarium culmorum causal agent of foot and root rot of wheat collected from two different fields in Tunisia

Fusarium culmorum is a major pathogen able to cause foot and root rot and the incitant of Fusarium head blight in wheat in Tunisia. The aims of the present study were to evaluate by PCR the type of mycotoxins produced, to determine the mating type and to analyse the genetic diversity by microsatellite markers of 82 F. culmorum isolates recovered from two separated Tunisian fields. Specific sequences in the Tri6-Tri5 intergenic region, Tri7 and Tri13 were used to identify 3-AcDON- or 15-AcDON-. All studied F. culmorum isolates, were of the 3-AcDON- type. No 15-AcDON- and NIV types were detected in this research. Both mating types MAT1-1 and MAT1-2 were recovered from the two fields in approximately equal proportions. Five polymorphic microsatellite markers were applied to F. culmorum isolates, to determine the genetic variation in and among populations. Sixty-four haplotypes were identified; the analysis of the population structure did not reveal a strong variation between fields. Total gene diversity (HT = 0.505; HS = 0.497) and analysis of molecular variance confirmed that most of the genetic variability was within populations (ΦST = 0.033; P < 0.0039). Gene flow (Nm = 31.05) indicated little differentiation among populations. Based on these results, the F. culmorum isolates collected from different fields might be part of one large panmictic population and in addition the low linkage disequilibrium values with high genetic variation within populations suggest that the population is recombining sexually.

Analysis of the diversity of Trichoderma spp. in soil horizons using digested ITS regions

We investigated the occurrence ofTrichoderma in the Oueslatia forest located in the centre-west of Tunisia, which represents a good example for studying a distribution ofTrichoderma between different soil horizons of a forest with Mediterranean bioclimate. One hundred-five isolates obtained were identified at the genus level by analysis of morphological characters. The diversity ofTrichoderma between soil horizons was evaluated by analysis of the internal transcribed spacer (ITS) of the rDNA region using restriction fragment length polymorphism (RFLP). The ITS region was first amplified by polymerase chain reaction (PCR) with specific primers and then cleaved with two restriction enzymes. Amplification products showed extensive length polymorphism and RFLP analysis generated bands ranging from 100 to 620 bp. The restriction profiles of the PCR products showed thatHaeIII enzyme has more discriminatory power thanRsaI. A high degree of polymorphism was detected in rhizosphere rather than soil. Thus the RFLP analysis produced different DNA profiles on the gels denoting significant intraspecific genetic variation. Our data confirm the potential of ITS region PCR-RFLP for the study of polymorphism amongTrichoderma population from different soil layers.

GENETIC DIVERSITY OF FABA BEAN (VICIA FABA L.) POPULATIONS ESTIMATED BY ISOZYMIC AND MOLECULAR MARKERS: RELATIONSHIP BETWEEN THE TWO METHODS

Introduction: Renal failure underlies various etiologies among which are infectious and autoimmune origins which may link directly or indirectly with blood groups. Objectives: To determine the frequency of blood groups among a sample of patients with renal failure at Royal medical services, and to investigate the association of renal function tests with blood groups. Methodology: A retrospective study design was followed to collect data from files of patients with renal failure. Files of renal patients was included if blood groups were written and kidney function tests were provided. A data sheet was made for each patient that included relevant information about renal patients. A total of 197 files were reviewed. Data were entered into excel sheet to make raw data for all patients. Data analysis was conducted using SPSS V20. Data were presented as frequencies and percentages. The relationships between blood groups and renal function tests were investigated using T-independent test. Significance was considered at alpha level 0.05), except for potassium level which was observed in its maximal level among patients with blood group A, and its minimal levels were observed among patients with blood group AB (p=0.032). Conclusions: The present study showed that renal failure patients exhibited more frequency with blood groups A and O and agreed with other studies in which blood group AB is the least associated blood group with renal failure. The level of potassium was highest in patients with blood group A and lowest in patients with blood group AB and this was statistically significant (p=0.032).