Status and Need of Research on Rhizobia and Arbuscular Mycorrhizal Fungi Associated with Leguminous Plants in Saudi Arabia

Most regions of Saudi Arabia are frequently subjected to high temperature and drought spells which destroy natural vegetation and lead to soil erosion and the advance of sand dunes.  The use of legume plants may help to preserve these ecosystems and to slow down desertification processes. Legumes produce extensive, deep root systems with a capacity to develop mycorrhizal and rhizobial symbioses facilitating the plant’s nutrition via enhanced soil nutrients absorption and atmospheric nitrogen fixation, respectively. These associations play a vital role in preserving and even restoring the fertility of poor and eroded soils. Research on tripartite associations of Arbuscular mycorrhizal fungi (AMF), rhizobia and legumes is rare in Saudi Arabia. Little is known about the diversity of these beneficial symbioses in Saudi ecosystems and their beneficial role for the sustainable management of range land. We attempted to explore the present status of research on rhizobia and AMF associated with various legumes in Saudi Arabia. The use of legume plants associated with microbial symbionts may be a useful asset in preserving fragile ecosystems and combating desertification. The identification of adapted and efficient legume-rhizobia-fungi tripartite associations in local ecosystems is of paramount importance for successful ecosystem restoration, rangeland and forest management and agricultural sustainability especially under unfavorable environmental conditions due to soil salinity, drought and heat stress

Priming improves germination and seed reserve utilization, growth, antioxidant responses and membrane stability at early seedling stage of Saudi sorghum varieties under drought stress

Seeds of three sorghum (Sorghum bicolor (L.) Moench.) varieties from Southwest Saudi Arabia were used to investigate the potential of osmopriming with polyethylene glycol (PEG 8000) to improve germination performance, seed reserve utilization and early seedling growth and drought stress tolerance. The primed (PS) and unprimed (UPS) seeds of the three sorghum varieties were germinated for 8 days under increasing PEG-induced osmotic stress. The treatments were arranged in a completely randomized design, in a factorial arrangement, with three sorghum cultivars (‘Zaydia’, ‘Shahbi’ and ‘Ahmar’) and four osmotic potentials (0.0; -0.4; -0.8 and -1.2 MPa) with four replicates of 50 seeds each. The results showed that drought stress affected seed germination and seedling emergence and establishment, but increased the activity of the antioxidant enzyme catalase (CAT). The strongest inhibition of germination and growth occurred at the highest PEG concentration and a significant difference was noticeable between the studied varieties. We confirmed also that seed osmopriming improved seed germination performance, seedling growth and enhanced the CAT activities while reduced malonyldialdehyde (MDA) accumulation and electrolyte leakage (EL) in the drought-stressed seedlings. Seed priming have enhanced also the α-amylase and total proteases activities in all varieties. The largest increase of these hydrolysing enzymes was shown in ‘Ahmar’. Furthermore, the PEG priming lead to improvement of the weight of utilized (mobilized) seed reserve (WUSR), seed reserve depletion percentage (SRDP) and total seedling dry weight (SLDW) of sorghum seedlings under water stress conditions. Still, the highest values or all three parameters were found in the ‘Ahmar’ variety. Under increasing drought stress conditions, ‘Ahmar’ showed the highest yield stability index (YSI) and the least EL and MDA contents in comparison to the other two varieties during the seedling establishment stage. Therefore, the former variety can tolerate better a rigorous water stress condition. ‘Zaydia’ appears to be the most vulnerable to drought stress. Thus, the use of species or varieties with eminent seed metabolic quality is an advantageous trait in drought-prone regions

Influence of light intensity and salinity on growth and antioxidant machinery of Thymus vulgaris L.

323-335Thymus vulgaris L. commonly known as Thyme or Garden Thyme, is important medicinal herb used for their wide-ranging therapeutic properties. Agriculture practices of thyme plants influence their growth and biochemical composition. Here, we have evaluated the effects of two production systems and irrigation with saline water on growth, physiological characteristics and antioxidant capacity of T. vulgaris. Two levels of salinity stress (50 and 150 mM) were applied for 2 and 4 weeks under shade enclosure or open field. The results showed that NaCl-treated plants grown in shade enclosure showed reduced total dry weight and relative water content, photosynthetic characteristics and leaf pigments when compared to full sunny conditions. However, the shade conditions enhanced glucose and fructose accumulation mainly after a short period of NaCl stress application. The reduction of Ca2+ and K+ was lower in NaCl-stressed plants grown under open-field conditions. Besides, under sunny conditions, plants showed significant increase in malondialdehyde (MDA) and H2O2 contents. Our results demonstrated that these plants in open field have higher contents of reduced ascorbate (ASC) and reduced glutathione (GSH) than plants grown in shade enclosure, which could be related to enhanced activity of APX and GR. An increase in superoxide dismutase (SOD) and catalase (CAT) activity was also recorded. Moreover, activities of dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR) were mainly dependent on the intensity of NaCl stress

Treatment of cancer with cryochemotherapy

Cryosurgery employs freezing to destroy solid tumours. However, frozen cells can survive and cause cancer recurrence. Bleomycin, an anticancer drug with a huge intrinsic cytotoxicity is normally not very effective because it is nonpermeant. We report that freezing facilitates bleomycin penetration into cells making it toxic to cryosurgery surviving cells at concentrations that are non-toxic systemically

influence of light intensity and salinity on growth and antioxidant machinery of Thymus vulgaris L

Thymus vulgarisL. commonly known as Thyme or Garden Thyme, is important medicinal herb used for their wide-ranging therapeutic properties. Agriculture practices of thyme plants influence their growth and biochemical composition. Here, we have evaluated the effects of two production systems and irrigation with saline water on growth, physiological characteristics and antioxidant capacity of T. vulgaris. Two levels of salinity stress (50 and 150 mM) were applied for 2 and 4 weeks under shade enclosure or open field. The results showed that NaCl-treated plants grown in shade enclosure showed reduced total dry weight and relative water content, photosynthetic characteristics and leaf pigments when compared to full sunny conditions. However, the shade conditions enhanced glucose and fructose accumulation mainly after a short period of NaCl stress application. The reduction of Ca2+ and K+ was lower in NaCl-stressed plants grown under open-field conditions. Besides, under sunny conditions, plants showed significant increase in malondialdehyde (MDA) and H2O2contents. Our results demonstrated that these plantsin open fieldhave higher contents of reduced ascorbate (ASC) and reduced glutathione (GSH) than plants grown in shade enclosure, which could be related to enhanced activity of APX and GR. An increase in superoxide dismutase (SOD) and catalase (CAT) activity was also recorded. Moreover, activities of dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR) were mainly dependent on the intensity of NaCl stress

Perspective Chapter: Rootstock-Scion Interaction Effect on Improving Salt Tolerance in Fruit Trees

Salt stress is a sever threat to global agriculture. Improving salt tolerance is a problematic task due to the large number of characteristics involved. Graft technique is a potential substitute to breeding and interesting practices to salt tolerance since it unites a scion and rootstock of two genotypes. Increased salinity tolerance in fruit trees will alter water relations, disrupt ionic balance, which can harm plant tissues and thus limit plant productivity. Therefore, the ability of fruit trees to resist salinity varies by species, although it is mostly determined by the type of their root systems. In this regard, the selection of salt-tolerant rootstocks can help maintain productivity under salinity. Several physiological and biochemical changes are attributed to the favorable response of grafting exerted by tolerant rootstocks or scion-rootstock interactions on yield and fruit attributes of plants in saline environments. Rootstocks provide grafted plants different salt tolerance mechanisms including the accumulation of compatible solutes and enhancing the antioxidant mechanisms in scion. The importance of grafting, strategies for selecting appropriate rootstocks, scion-rootstock interaction for growth and the tolerance mechanisms used by plants to avoid the effects of salt stress, are all discussed in this review. Grafting’s potential challenges are also discussed

Effectiveness of regional diffusion MRI measures in distinguishing multiple sclerosis abnormalities within the cervical spinal cord

ABSTRACT: Introduction Multiple sclerosis (MS) is an inflammatory disorder of the central nervous system. Although conventional magnetic resonance imaging (MRI) is widely used for MS diagnosis and clinical follow-up, quantitative MRI has the potential to provide valuable intrinsic values of tissue properties that can enhance accuracy. In this study, we investigate the efficacy of diffusion MRI in distinguishing MS lesions within the cervical spinal cord, using a combination of metrics extracted from diffusion tensor imaging and Ball-and-Stick models. Methods We analyzed spinal cord data acquired from multiple hospitals and extracted average diffusion MRI metrics per vertebral level using a collection of image processing methods and an atlas-based approach. We then performed a statistical analysis to evaluate the feasibility of these metrics for detecting lesions, exploring the usefulness of combining different metrics to improve accuracy. Results Our study demonstrates the sensitivity of each metric to underlying microstructure changes in MS patients. We show that selecting a specific subset of metrics, which provide complementary information, significantly improves the prediction score of lesion presence in the cervical spinal cord. Furthermore, the Ball-and-Stick model has the potential to provide novel information about the microstructure of damaged tissue. Conclusion Our results suggest that diffusion measures, particularly combined measures, are sensitive in discriminating abnormal from healthy cervical vertebral levels in patients. This information could aid in improving MS diagnosis and clinical follow-up. Our study highlights the potential of the Ball-and-Stick model in providing additional insights into the microstructure of the damaged tissue

An optimized method for detecting gamma-H2AX in blood cells reveals a significant interindividual variation in the gamma-H2AX response among humans

Phosphorylation of histone H2AX on serine 139 (gamma-H2AX, γH2AX) occurs at sites flanking DNA double-strand breaks (DSBs) and can provide a measure of the number of DSBs within a cell. Here we describe a rapid and simple flow-cytometry-based method, optimized to measure gamma-H2AX in non-fixed peripheral blood cells. No DSB induced signal was observed in H2AX−/− cells indicating that our FACS method specifically recognized gamma-H2AX accumulation. The gamma-H2AX assay was capable of detecting DNA damage at levels 100-fold below the detection limit of the alkaline comet assay. The gamma-H2AX signal was quantitative with a linear increase of the gamma-H2AX signal over two orders of magnitude. We found that all nucleated blood cell types examined, including the short-lived neutrophils induce gamma-H2AX in response to DSBs. Interindividual difference in the gamma-H2AX signal in response to ionizing radiation and the DSB-inducing drug calicheamicin was almost 2-fold in blood cells from patients, indicating that the amount of gamma-H2AX produced in response to a given dose of radiation varies significantly in the human population. This simple method could be used to monitor response to radiation or DNA-damaging drugs

Management of cutaneous metastases using electrochemotherapy

Background. Cutaneous metastases may cause considerable discomfort as a consequence of ulceration, oozing, bleeding and pain. Electrochemotherapy has proven to be highly effective in the treatment of cutaneous metastases. Electrochemotherapy utilises pulses of electricity to increase the permeability of the cell membrane and thereby augment the effect of chemotherapy. For the drug bleomycin, the effect is enhanced several hundred-fold, enabling once-only treatment. The primary endpoint of this study is to evaluate the efficacy of electrochemotherapy as a palliative treatment. Methods. This phase II study is a collaboration between two centres, one in Denmark and the other in the UK. Patients with cutaneous metastases of any histology were included. Bleomycin was administered intratumourally or intravenously followed by application of electric pulses to the tumour site. Results. Fifty-two patients were included. Complete and partial response rate was 68% and 18%, respectively, for cutaneous metastases <3 cm and 8% and 23%, respectively, for cutaneous metastases >3 cm. Treatment was well-tolerated by patients, including the elderly, and no serious adverse events were observed. Conclusions. ECT is an efficient and safe treatment and clinicians should not hesitate to use it even in the elderly