Mustapha Rouissi

Broomrapes (Orobanche and Phelipanche spp.) are non-achlorophyllous parasitic plants belonging to the Orobanchaceae family, with some species evolving to infest agricultural crops, causing substantial economic losses. This study focuses on Orobanche and Phelipenche species prevalent in Tunisia, particularly Orobanche crenata, Orobanche foetida and Phelipanche ramosa, which pose a significant threat to legume crops and other agronomically important plants. These parasitic species cause severe damage before their aboveground appearance, making early detection and management crucial. Successful breeding programs targeting their hosts necessitate a comprehensive understanding of the genetic variability within different broomrape populations. A plethora of molecular markers, including RAPD, ISSR, AFLP, SSR and SNPs, were employed to evaluate the genetic diversity of Orobanche spp., mainly in Mediterranean countries. This research seeks to analyze the genetic variability and structure of thirty-four (34) Tunisian Orobanche and Phelipanche populations infesting various crops and wild plants. The results demonstrated a higher genetic differentiation within populations rather than between populations and no clear differentiation based on the geographic origins of the populations. By measuring the genetic diversity of a large number of broomrape populations that affect both wild species and crops, this study aims to support efforts toward establishing effective management approaches.

Overall, 180 yeasts and bacteria isolated from the peel of citrus fruits were screened for their in vitro antagonistic activity against Penicillium digitatum and P. italicum, causative agents of green and blue mold of citrus fruits, respectively. Two yeast and three bacterial isolates were selected for their inhibitory activity on mycelium growth. Based on the phylogenetic analysis of 16S rDNA and ITS rDNA sequences, the yeast isolates were identified as Candida oleophila and Debaryomyces hansenii while the bacterial isolates were identified as Bacillus amyloliquefaciens, B. pumilus and B. subtilis. All five selected isolates significantly reduced the incidence of decay incited by P. digitatum and P. italicum on ‘Valencia’ orange and ‘Eureka’ lemon fruits. Moreover, they were effective in preventing natural infections of green and blue mold of fruits stored at 4 °C. Treatments with antagonistic yeasts and bacteria did not negatively affect the quality and shelf life of fruits. The antagonistic efficacy of the five isolates depended on multiple modes of action, including the ability to form biofilms and produce antifungal lipopeptides, lytic enzymes and volatile compounds. The selected isolates are promising as biocontrol agents of postharvest green and blue molds of citrus fruits.

Increasing interest in using rhizobia as biofertilizers in smallholder agricultural farming systems has prompted scientists to investigate rhizobia diversity, resulting in the identification of many strains. Fifty-five Rhizobium strains nodulating in the common bean (Phaseolus vulgaris L.) were isolated from soil samples from different areas of Tunisia and phenotypically characterized to determine their symbiotic nitrogen fixation capabilities. Their tolerance to pH, salinity, temperature and alkalinity, as well as their cultural and biochemical characteristics indicated wide physiological diversity. These phenotypic characteristics significantly affected rhizobia growth, and strains of interest were identified and used in inoculation trials. They were efficient and able to tolerate pH from 4 to 9, NaCl concentrations of 25 to 100 mM, temperature variation from 10 to 40 °C, and lime (CaCO₃) from 0.05 to 0.20 mM. Selected Rhizobium strains were identified as candidates for biofertilizer production for a variety of Tunisian soil types.

Faba bean (Vicia faba L.) Algerian accessions represent an essential source of traits of interest for crop improvement, especially for tackling climate change, because their genetic background and potential have not been well studied. The purpose of this research was to assess the genetic variability of 14 Algerian faba bean accessions by means of 10 agro-morphological traits and 7 simple sequence repeat markers (SSRs). ANOVA analysis showed a large significant phenotypic variation in fruit setting (FS), seed length (SL), seed width (SW), and 100-seeds weight (HSW), which arose as the main discriminant characters as revealed by principal component analysis (PCA). In addition, SSR analysis identified a total of twenty different alleles within our collection with a mean of 2.85 alleles per locus. The polymorphism information content (PIC) ranged from 0.32 to 0.58, with a mean of 0.44. Observed heterozygosity (Ho) ranged from 0.57 to 1.00 with a mean of 0.72, while the expected one (He) varied from 0.42 to 0.67, reaching a mean of 0.57. Based on agro-morphological as well as molecular data, the 14 accessions were not clustered according to the geographical pattern, as also confirmed by principal coordinate analysis (PCoA). Moreover, AMOVA highlighted that most of the overall genetic variation within our collection was the result of strong differentiation among accessions (84%). Finally, the Mantel test revealed that there was no substantial correlation between the molecular and agro-morphological traits (r = −0.025, p > 0.05). These findings represent a first step toward faba been breeding programs establishment in Algeria, indicating that our collection exhibited optimal agro- and molecular diversity to identify specific traits useful in Mediterranean environment.

The Tunisian durum wheat germplasm includes modern cultivars and traditional varieties that are still cultivated in areas where elite cultivars or intensive cultivation systems are not suitable. Within the frame of a collection program of the National Gene Bank of Tunisia (NGBT), durum wheat germplasm was collected from different Tunisian agro-ecological zones. The collected samples were studied using simple sequence repeats (SSRs) markers to explore the genetic diversity and evaluate the genetic structure in Tunisian germplasm. The results demonstrated significant diversity in the Tunisian durum wheat germplasm, with clear differentiation between traditional varieties and modern cultivars. The population structure analysis allowed the identification of five subpopulations, two of which appear to be more strongly represented in germplasm collected in central and southern Tunisia, where environmental conditions at critical development phases of the plant are harsher. Moreover these subpopulations are underrepresented in modern varieties, suggesting that traits of adaptation useful for breeding more resilient varieties might be present in central and southern germplasm. Moreover, our results will support, the activity of in situ on farm conservation of Tunisian durum wheat germplasm started by the National Gene Bank of Tunisia along with the ex situ approach.

According to the United States Department of Agriculture (USDA), Tunisia’s proportion of durum wheat production out of its total wheat harvest is always the highest of the Maghreb countries, comprising about 80% of Tunisia’s total wheat harvest. The goals of the Tunisian government include technology exchange, increasing certified seed usage, and reaching 120,000 ha of irrigated cereals in the short term. The new Tunisian cultivars are often characterized by high grain yield and are more responsive to increased seeding rates, added nitrogen fertilizer use, and additional supplementary irrigation and receptive to appropriate weed control techniques (Rezgui et al. 2008). However, most of the available water resources are of medium to poor quality, and the saline content is often high (Mougou et al. 2011). In arid and semiarid regions of Tunisia, the use of low-quality water for irrigation is accompanied by risks leading to plant stress and soil salinization with associated harmful consequences on plant development and yield. Salt accumulation in arable soils is mainly derived from 244irrigation water that contains trace amounts of sodium chloride (NaCl) and from seawater (Deinlein et al. 2014). In many coastal areas of Tunisia, excessive groundwater pumping from coastal freshwater wells increases saltwater intrusion, which leads to land contamination and salinization. Currently, about 50% of the total irrigated areas in Tunisia are considered at high risk for salinization (Bouksila et al. 2011). In these regions, salinity is one of the serious environmental problems, causing osmotic stress and reduction in plant growth and crop productivity. Projected climate-change impacts, rising temperature, rise in potential evapotranspiration rates, and declining rainfall exacerbate this problem of salinity.

Background. Foot mycoses are a frequent disease that represents a public health problem worldwide.Objectives. This study aims to evaluate the epidemiology of foot mycoses among Tunisian patients, in order to determine the fungal etiological agents and to identify possible risk factors.Patients and Methods. A prospective study of three hundred and ninety-two patients was undertaken during one year (2013-2014). All subjects were asked to collect demographic data related to the risk factors of foot mycoses. A complete mycological diagnosis was carried out on all patients.Results. A total of 485 samples were collected; tinea pedis and tinea unguium were confirmed in 88.2% of cases. Dermatophytes were isolated in 70.5% and the most frequent pathogen wasTrichophyton rubrum(98.1%), followed by yeasts (17.7%) commonlyCandida parapsilosis. Non-dermatophyte molds (NDMs) were observed in 8.02% cases andFusariumsp. was the frequent genus (29.1%). The main predisposing factors of fungal foot infections were practicing ritual washing (56.6%) and frequentation of communal showers (50.5%).Conclusion. This is a recent survey of foot mycoses in Tunisia. Epidemiological studies can be useful to eradicate these infections and to provide further measures of hygiene and education.

This study aims to evaluate the physiological behaviour of 50 genotypes of durum wheat (Triticum durum Desf) in salt stress conditions at germination stage. In this context, a trial was conducted in a growth chamber with controlled temperature and photoperiod. The seeds are germinated in Petri dishes containing fresh water in one case and in the presence of NaCl (10 g/l) in another case for 8 days. The measurements were for the final germination, germination kinetics, the length of the shoot and epicotyl. The results show that salt reduces the germination capacity and speed of germination, as it affected the stem and root growth of the genotypes studied. The response of seeds to salt stress varies over time with this case, given that the final percentage of germination and seedling growth differed significantly between the species studied. The variety DZA75: 93,151 has been the most tolerant to salt stress with a germination rate of 81.33% then the variety ESP-85028 has shown the most sensitive to this stress with a germination rate of order of 0.66%.