Natural genetic variation in Calligonum Tunisian genus analyzed by RAPD markers

The Calligonum genus is one of the most economically important resources of the Tunisian desert, playing an important role in the lives of desert local population. A great range of genetic diversity could be seen in diverse populations of this genus which are spread all over Tunisian areas. DNA-based molecular markers are playing increasingly important role in the analysis of genetic diversity in wide range of plants. This study is an attempt to collect, compile and collate information on the existing natural genetic diversity, at intra-specific and inter-populational levels in Calligonum genus (C.azel, C.arich and C.comosum). This study deals with 16 genotypes of Calligonum (Polygonaceae) collected from different regions of Tunisian desert using random amplified polymorphic DNA (RAPD) marker. In total, 46 polymorphic bands amplified by 4 random primers, with the polymorphic rate of 89.06% were recorded. The commercial software package SPSS 16 was used to develop similar matrices based on the Dice coefficient which is defined as 2a/2a+u, where “a” is the number of positive matches and “u” is the number of non-matches. From the analysis, it is imperative that predominantly obligate out breeding behavior of Calligonum genus, helps these diverse accessions to spread and occupy specific geographical niches in the Tunisian arid regions.Key words: Calligonum, genetic diversity, Inter-specific variation, RAPD marker, Tunisian desert

Simultaneous application of salicylic acid and calcium improves salt tolerance in two contrasting tomato (Solanum lycopersicum) cultivars

Soil salinity is one of the most important environmental factors responsible for serious agricultural problems. Tomato salt tolerance may be improved by genetic selection and by the use of adapted physiological tools. The aim of this study was to investigate the impact of exogenous application of salicylic acid (SA 0.01 mM) and calcium sulphate (CaSO4 5 mM), singly or in combination, on plant growth, photosynthetic pigments, nutritional behaviour and some metabolic parameters (total chlorophyll, carotenoids, soluble sugars, proline and lipid peroxidation) of two tomato cultivars (cv. Super Marmande and cv. Red River) exposed to salt stress (100 mM NaCl). Application of 100 mMNaCl reduced plant growth, total chlorophyll and carotenoid contents. Salt stress also induced an accumulation of Na+, a decrease in K+ and Ca2+ concentration and root sugar level, an increase in malondialdehyde (MDA) and proline concentration. Deleterious impact of salinity was related to modification in ion content rather than modification in the plant water status. Exogenous application of SA or Ca alone improved plant behaviour in the presence of NaCl. Nevertheless, the best results in terms of growth, photosynthetic pigment concentrations and mineral nutrition (limitation of Na+ accumulation and maintenance of K+ and Ca2+ content)were obtained in response to the combined SA+Ca treatment. Although the involved physiological parameters Varied depending on the considered cultivar, our results suggest that Ca2+ and SA may interact to reduce the stress experienced by the plant in the presence of NaCl

Anti-Inflammatory Potential of Compounds Isolated from Tunisian Lichens Species

The lichen's special symbiotic structure enables it to produce bioactive substances. They have historically been recognized for their aesthetic and medicinal benefits. Furthermore, in recent years, they have performed in various fields, including perfumery, dyeing, and pharmacology due to their rich secondary metabolites. From our study, four compounds were isolated from organic extracts of Parmotrema hypoleucinum, Roccella phycopsis, and Xanthoria parietina and identified by spectroscopic investigation as atranorin, (+)-iso-usnic acid, methyl orsellinate, and parietin, respectively. The anti-inflammatory effects of lichens extracts, and pure compounds were evaluated on RAW 264.7 macrophages cells at different concentrations. At 25 μg/mL all treated samples did not show any effect on cell viability. Atranorin and (+)-iso-usnic acid showed an inhibitory effect on nitric oxide (NO) levels in lipopolysaccharide (LPS)-stimulated macrophages. Nitric oxide (NO) production was measured using Griess reagent, atranorin and (+)-iso-usnic acid showed a high anti-inflammatory potential (75.99 % and 57.27 % at 25 μg/mL). On the other hand, methyl orsellinate and the organic extracts of three lichens showed good anti-inflammatory activity ranging from 29.16 % at 25 μg/mL to 86.91 % at 100 μg/mL

Acclimation to soil flooding - sensing and signal-transduction

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