Composition and Diversity of the Culturable Endophytic Community of Six Stress-Tolerant Dessert Plants Grown in Stressful Soil in a Hot Dry Desert Region.

Saudi Arabia is part of a hot dry desert region and is characterized by stressful conditions. The main goal of this research was to identify endophytic fungal (EF) community composition, diversity and abundance in relation to their plant hosts and soil stress. The above-ground parts of six wild plants (Haloxylon salicornicum, Salsola kali, Heliotropium bacciferum, Erica verticillata, Salsola imbricata and Bienertia sinuspersici) were sampled, surface-sterilized and cut into small pieces, which were cultured and incubated for 4-6 weeks. Isolates were grouped and identified by using both morphological and ITS rDNA molecular data. The diversity and community structure of plant-endophyte associations were studied. A total of 455 EF isolates were grouped into 25 different taxa; 21 of which were identified at the species level, 2 at genus level and 2 were unclassified fungi. Here, 95.65% of the identified genera were Ascomycota; of which 36.36, 31.81 and 31.81% were members of the classes Dothideomycetes, Eurotiomycetes and Sordariomycetes, respectively. S. imbricata showed the highest isolation rate and colonization frequency (CF%) of EF when compared to other plant species. Additionally, S. imbricata demonstrated the highest species richness and species diversity of the EF community predominated by the genus Fusarium. Conclusively, the core culturable EF genera of six wild plants were identified (unculturable taxa were not identified in this study). The composition of the EF community was revealed to have a strong correlation to both the electrical conductivity and pH of the soil and a moderate correlation to both the host species and the host family. The abundance and diversity of EF communities of the six plants were environment-dependent.

Effect of extreme temperature changes on phenolic, flavonoid contents and antioxidant activity of tomato seedlings (Solanum lycopersicum L.).

BACKGROUND: Climatic changes are the most important abiotic factor affecting plant growth, crop quality and nutritional value. Plants exposed to thermal stress respond by accumulation of secondary metabolites/molecules (SMs). Tomato (Solanum lycopersicum) is a cosmopolitan crop, eaten by most of the world's people because it is highly nutritious plant. It is cultivated in more than 16 thousand hectares in Saudi Arabia and thus is influenced by extreme climatic changes. OBJECTIVE: In the current study, the phytochemical effect of thermal stress was investigated in seedlings of S. lycopersicum. Such information will be very helpful in developing more tolerant tomato cultivars in a climate change scenario. METHODS: Seedlings of S. lycopersicum were subjected to heat shock; HS1 and HS2 (45 and 50 °C) and cold shock; CS (4 °C) in comparison to control; Con (25 °C). Phenolic compounds, flavonoids, total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity were estimated under the four temperature treatments. RESULTS: Using 23 standards (17 phenolic and six flavonoids), HPLC resulted in the estimation of 16, 20, 15 and 18 compounds for Con, CS, HS1 and HS2, respectively. Differences in the amounts of total phenolics, and total flavonoids were strongly correlated to thermal stress. CS plants exhibited the highest number of signals and the highest absolute quantities of total phenolics, flavonoids and sum of both. The major peaks of phenolics were (Chlorogenic acid, Resvertol), (Vanillic acid, Benzoic acid, Quinol), (Vanillic acid, Benzoic acid) and (Vanillic acid, Benzoic acid) for Con, CS, HS1 and HS2, respectively. The major peaks of flavonoids were (Quercetin, Myricetin), (Quercetin, Rutin), (Quercetin, Rutin, Catechin) and (Quercetin) for Con, CS, HS1 and HS2, respectively. CS plants contain the highest amounts of Benzoic acid (8010.37 mg/kg FW) and Quercetin (2319.48 mg/kg FW). The highest TPC (131 mg GAE/100 g FW) and TFC (61 mg QE/100 g FW) were determined in the case of CS plants. In terms of IC50s, the CS plants showed the highest antioxidant activities (lowest values) in both of DPPH (467.73 µM TE/100 g FW) and ABTS (8.97 µM TE/100 g FW) assays. CONCLUSIONS: Our findings supported that the complexity and quantity of phenolics and flavonoids in tomato's extract are strongly related to thermal stress. Additionally, the CS plants demonstrated more desirable phytochemical profile over the other treatments. CS plants exhibited higher number, absolute amounts of SMs, higher TPC and TFC than those of Con, HS1 and HS2 plants. Additionally, CS plants showed higher antioxidant activity than that of both HS1 and HS2 plants. Such results are very useful in justifying mechanism of tolerance in tomato plant to thermal stress in the context of climate change. Additional research has turned on to reveal molecular response of tomato to such thermal stress.

Characterization of multisugar-binding C-type lectin (SpliLec) from a bacterial-challenged cotton leafworm, Spodoptera littoralis.

BACKGROUND: Various proteins that display carbohydrate-binding activity in a Ca(2+)-dependent manner are classified into the C-type lectin family. They have one or two C-type carbohydrate-recognition domains (CRDs) composed of 110-130 amino acid residues in common. C-type lectins mediate cell adhesion, non-self recognition, and immuno-protection processes in immune responses and thus play significant roles in clearance of invaders, either as cell surface receptors for microbial carbohydrates or as soluble proteins existing in tissue fluids. The lectin of Spodoptera littoralis is still uncharacterized. METHODOLOGY: A single orf encoding a deduced polypeptide consisting of an 18-residue signal peptide and a 291-residue mature peptide, termed SpliLec, was isolated from the haemolymph of the cotton leafworm, S. littoralis, after bacterial challenge using RACE-PCR. Sequence analyses of the data revealed that SpliLec consists of two CRDs. Short-form CRD(1) and long-form CRD(2) are stabilized by two and three highly conserved disulfide bonds, respectively. SpliLec shares homology with some dipteran lectins suggesting possible common ancestor. The purified SpliLec exhibited a 140-kDa molecular mass with a subunit molecular mass of 35 kDa. The hemagglutination assays of the SpliLec confirmed a thermally stable, multisugar-binding C-type lectin that binds different erythrocytes. The purified SpliLec agglutinated microorganisms and exhibited comparable antimicrobial activity against gram (+) and gram (-) bacteria too. CONCLUSIONS: Our results suggested an important role of the SpliLec gene in cell adhesion and non-self recognition. It may cooperate with other AMPs in clearance of invaders of Spodoptera littoralis.

Identification, phylogenetic analysis and expression profile of an anionic insect defensin gene, with antibacterial activity, from bacterial-challenged cotton leafworm, Spodoptera littoralis.

BACKGROUND: Defensins are a well known family of cationic antibacterial peptides (AMPs) isolated from fungi, plants, insects, mussels, birds, and various mammals. They are predominantly active against gram (+) bacteria, and a few of them are also active against gram (-) bacteria and fungi. All insect defensins belonging to the invertebrate class have a consensus motif, C-X5₋16-C-X3-C-X9₋10-C-X4₋7-CX1-C. Only seven AMPs have already been found in different lepidopteran species. No report was published on the isolation of defensin from the Egyptian cotton leafworm, Spodoptera littoralis. RESULTS: An anionic defensin, termed SpliDef, was isolated from the haemolymph of the cotton leafworm, S. littoralis, after bacterial challenge using differential display technique. Based on sequence analyses of the data, specific primers for full length and mature peptide of defensin were designed and successfully amplified 471 and 150 bp amplicons. The integration of the results revealed that the 471 bp-PCR product has one open reading frame (orf) of 303 bp long, including both start codon (AUG) and stop codon (UGA). The deduced peptide consists of a 23-residues signal peptide, a 27-residues propeptide and a 50-residues mature peptide with the conserved six-cysteine motif of insect defensins. Both haemolymph and expressed protein exhibited antibacterial activities comparable to positive control. The RT-qPCR indicated that it was more than 41-folds up-regulated at 48 h p.i. CONCLUSION: Our results highlight an important immune role of the defensin gene in Spodoptera littoralis by cooperating with other AMPs to control bacterial infection.

Role of Culex and Anopheles mosquito species as potential vectors of rift valley fever virus in Sudan outbreak, 2007.

BACKGROUND: Rift Valley fever (RVF) is an acute febrile arthropod-borne viral disease of man and animals caused by a member of the Phlebovirus genus, one of the five genera in the family Bunyaviridae. RVF virus (RVFV) is transmitted between animals and human by mosquitoes, particularly those belonging to the Culex, Anopheles and Aedes genera. METHODS: Experiments were designed during RVF outbreak, 2007 in Sudan to provide an answer about many raised questions about the estimated role of vector in RVFV epidemiology. During this study, adult and immature mosquito species were collected from Khartoum and White Nile states, identified and species abundance was calculated. All samples were frozen individually for further virus detection. Total RNA was extracted from individual insects and RVF virus was detected from Culex, Anopheles and Aedes species using RT-PCR. In addition, data were collected about human cases up to November 24th, 2007 to asses the situation of the disease in affected states. Furthermore, a historical background of the RVF outbreaks was discussed in relation to global climatic anomalies and incriminated vector species. RESULTS: A total of 978 mosquitoes, belonging to 3 genera and 7 species, were collected during Sudan outbreak, 2007. Anopheles gambiae arabiensis was the most frequent species (80.7%) in White Nile state. Meanwhile, Cx. pipiens complex was the most abundant species (91.2%) in Khartoum state. RT-PCR was used and successfully amplified 551 bp within the M segment of the tripartite negative-sense single stranded RNA genome of RVFV. The virus was detected in female, male and larval stages of Culex and Anopheles species. The most affected human age interval was 15-29 years old followed by > or = 45 years old, 30-44 years old, and then 5-14 years old. Regarding to the profession, housewives followed by farmers, students, shepherd, workers and the free were more vulnerable to the infection. Furthermore, connection between human and entomological studies results in important human case-vulnerability relatedness findings. CONCLUSION: Model performance, integrated with epidemiologic and environmental surveillance systems should be assessed systematically for RVF and other mosquito-borne diseases using historical epidemiologic and satellite monitoring data. Case management related interventions; health education and vector control efforts are extremely effective in preparedness for viral hemorrhagic fever and other seasonal outbreaks.

Preventive effect of the flavonoid, quercetin, on hepatic cancer in rats via oxidant/antioxidant activity: molecular and histological evidences.

BACKGROUND: The incidence of hepatocellular carcinoma is increasing in many countries. The estimated number of new cases annually is over 500,000, and the yearly incidence comprises between 2.5 and 7% of patients with liver cirrhosis. The incidence varies between different geographic areas, being higher in developing areas; males are predominantly affected, with a 2:3 male/female ratio METHODS: Experiments were designed to examine the effect of N-Nitrosodiethylamine (NDEA) as cancer-inducer compound and to confirm the preventive effect of the flavonoid quercetin on hepatocellular carcinoma in rats. Briefly, thirty six male albino rats of Wistar strain were divided into 3 groups: the 1st group was administered NDEA alone (NDEA-treated), the 2nd group was treated simultaneously with NDEA and quercetin (NDEA+Q) and the 3rd group was used as control (CON). Randomly amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) as well as p53-specifi PCR assays were employed to determine genomic difference between treated, and control animals. Histological confirmation as well as oxidant/antioxidant status of the liver tissue was done. RESULTS: RAPD analysis of liver samples generated 8 monomorphic bands and 22 polymorphic bands in a total of 30-banded RAPD patterns. Cluster analysis and statistical analyses of RAPD data resulted in grouping control and NDEA+Q samples in the same group with 80% similarity cut-off value. NDEA-treated samples were clustered in a separate group. Specific PCR assay for polymorphism of P53 gene revealed a uniform pattern of allele separation in both control and NDEA+Q samples. Quercetin anticancer effect was exhibited in significant decrease of oxidative stress and significant decrease of antioxidant activity. Histopathological studies showed normal liver histology of the NDEA+Q samples. Meanwhile, several cancer-induced features were clearly observable in NDEA-treated samples. CONCLUSION: This paper demonstrated that preventive effect of quercetin on hepatocarcinoma in rats by RAPD-PCR, tracing the effect on p53 gene and by histopathological evidence. Hereby, it was proved that quercetin exerted its preventive effect via decreased oxidative stress and decreased antioxidant activity.

Characterization of an Egyptian Spodoptera littoralis nucleopolyhedrovirus and a possible use of a highly conserved region from polyhedrin gene for nucleopolyhedrovirus detection.

An Egyptian isolate of Spodoptera littoralis nucleopolyhedrovirus (SpliNPV) was tested for its potential as biocontrol agent in comparison to Autographa californica multiple nucleopolyhedrovirus (AcMNPV). Comparative assays of SpliNPV and AcMNPV against 2nd instar larvae of Spodoptera littoralis revealed 4-fold greater susceptibility of S. littoralis to AcMNPV than to SpliNPV based on LC50 values for the two viruses. The LT50s determined for SpliNPV and AcMNPV using LC50 of the virus against 2nd instar larvae were 4.2 and 5.8 days, respectively. A DNA segment of 405 bp containing highly conserved region from polyhedrin gene of SpliNPV (Polh-cr) was successfully amplified by PCR. Subsequently, this DNA segment was cloned and sequenced. Nucleotide sequence and its deduced amino acid sequence were compared to all available sequences in GenBank. Sequence alignment results revealed that Polh-cr showed significant similarities with 91 different baculovirus isolates. The percentage of homology ranged from 78% for Plusia orichalcea NPV to 99% for SpliNPV. This highly conserved region provides a candidate that could be used in easy, fast and economic prospective systems for virus detection as well as in biological control strategies.