Influence of mycorrhizal inoculation on carrot growth,metabolites and nutrition

Mycorrhizae are fungal symbionts forming mutualistic relationships with plant roots. This study was undertaken to evaluate the overall influence of arbuscular mycorrhizal fungi (AMF) on the overall growth and development of carrot plant. Surface-sterilized seeds of carrot were sown in earthen pots filled with sterile soil. Half of the pots were inoculated with AMF spores; the other half without any AMF inoculation represented control. After germination inoculated plants, along with the controls, were sampled at 20, 40, 60 and 80 days of growth after seedling emergence. There is a progressive net increase in growth with each 20-day interval after seedling emergence. Storage roots of carrot had a higher level of metabolites and nutrients like nitrogen, phosphorus and potassium in mycorrhiza colonized plants than the control. High performance liquid chromatography analysis indicated an increase in the carbohydrate fractions in AMF-inoculated roots. Thus, mycorrhiza has been found increasing the growth, metabolites and nutrition of carrot plant.     

Effects of pre-sowing treatments on seed germination of <Emphasis Type="Italic">Melia azedarach</Emphasis>

A germination experiment of pre-treated seeds of Melia azedarach was conducted in the nursery of Forestry and Wood Technology Discipline, Khulna University, Bangladesh. Matured seeds of Melia azedarach were collected from healthy trees of National Botanical Garden, Bangladesh and were treated with five pre-sowing treatments (control, immersion in cold water, immersion in hot water, scarification with sand paper, and immersion in concentrated H₂SO₄) on seed germination. Results revealed that the germination rates of pre-sowing treated seeds were significantly increased compared to those in control, except for cold water treatment. The highest germination success (80%) was found in scarification with sand paper, followed by 74% and 69% in immersion in H₂SO₄ and hot water treatment, respectively. Germination started on 8–11 days and completed on 20–21 days of the germination period in all cases. Analysis of variance showed the significance difference in germination success among the treatments but no significance difference in germination period among the treatment. Hot water treatment may be recommended on seed germination of the species in rural Bangladesh.     

Bioprospecting Red Sea Coastal Ecosystems for Culturable Microorganisms and Their Antimicrobial Potential

Microorganisms that inhabit unchartered unique soil such as in the highly saline and hot Red Sea lagoons on the Saudi Arabian coastline, represent untapped sources of potentially new bioactive compounds. In this study, a culture-dependent approach was applied to three types of sediments: mangrove mud (MN), microbial mat (MM), and barren soil (BS), collected from Rabigh harbor lagoon (RHL) and Al-Kharrar lagoon (AKL). The isolated bacteria were evaluated for their potential to produce bioactive compounds. The phylogenetic characterization of 251 bacterial isolates based on the 16S rRNA gene sequencing, supported their assignment to five different phyla: Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes, and Planctomycetes. Fifteen putative novel species were identified based on a 16S rRNA gene sequence similarity to other strain sequences in the NCBI database, being ≤98%. We demonstrate that 49 of the 251 isolates exhibit the potential to produce antimicrobial compounds. Additionally, at least one type of biosynthetic gene sequence, responsible for the synthesis of secondary metabolites, was recovered from 25 of the 49 isolates. Moreover, 10 of the isolates had a growth inhibition effect towards Staphylococcus aureus, Salmonella typhimurium and Pseudomonas syringae. We report the previously unknown antimicrobial activity of B. borstelensis, P. dendritiformis and M. salipaludis against all three indicator pathogens. Our study demonstrates the evidence of diverse cultured microbes associated with the Red Sea harbor/lagoon environments and their potential to produce antimicrobial compounds.     

Morphological and Genetical Variability among Rhizoctonia solani Isolates Causing Sheath Blight Disease of Rice

Eighteen isolates of Rhizoctonia solani collected from infected rice plants in four different locations of Bangladesh were studied by using morphological characters and molecular markers. Anastomosis study with a reference isolate confirmed that all the isolates belonged to R. solani. Significant variation was observed in sclerotial size, shape and distribution. Un-weighted pair group method with arithmetic mean dendrogram constructed based on the Gower's general similarity coefficient showed that these isolates were grouped into four clusters at the 0.68 similarity coefficent according to morphological characters. Cluster I was a major cluster consisting of 13 isolates, while clusters Ⅱ to Ⅳ consisted of 1 or 2 isolates. Analyses by variable number of tandem repeat and amplified fragment length polymorphism markers showed that the isolates were grouped into five and three clusters at a similarity coefficient of 0.64 and 0.69, respectively. Although most of the variability was found between isolates from different regions as expected, significant variation was observed within the isolates collected from similar agro-ecological regions. Our results suggest the presence of different races of R. solani within the same local geographic regions.     

Bioavailability of Calcium,Iron and Zinc Fortified Whole Wheat Flour Chapatti

The bioavailability and interactive effects of calcium, iron and zinc fortified whole wheat flour chapattis on female Sprague–Dawley albino rats were determined. The whole wheat flour was fortified with CaCO₃, FeSO₄ and ZnSO₄ at 1000, 40 and 20 mg/kg, respectively and fed to 64 female Sprague–Dawley rats for 4 weeks. Retention of Ca, Fe and Zn was determined in plasma, femur and liver tissues. Ca levels in plasma and liver did not alter significantly while the Ca retention in femur changed significantly with the change in fortificants. The calcium retention was higher in the femur of rats fed on the diet supplemented with Ca + Zn (221 ± 13.61 mg/g) than the rats fed on the diet supplemented with Ca + Fe (219 ± 18.92 mg/g). The iron in plasma, liver and femur ranged from 2.19 ± 0.11 to 2.77 ± 0.10 μg/ml, 203.5 ± 13.24 to 251.5 ± 17.19 μg/g and 43.5 ± 1.05 to 52 ± 2.07 μg/g while zinc content ranged from 1.31 ± 0.089 to 1.55 ± 0.114 μg/ml, 89.5 ± 3.41 to 132 ± 6.10 μg/g and 175 ± 8.29 to 191 ± 10.85 μg/g, respectively. The minerals interacted with each other resulting in decrease of bioavailability among each other. The absorption was higher in the rats fed on fortified diet than those fed on unfortified chapatti diet. Hence, it is concluded that fortification of whole wheat flour is feasible to overcome the Ca, Fe and Zn malnutrition in the vulnerable groups.     

The hypocholesterolemic and antioxidative effect of dietary diosgenin and chromium chloride supplementation on high-cholesterol fed Japanese quails

The current study investigated the effect of natural diosgenin extracted from fenugreek seeds, in comparison with the pure standard diosgenin, plus chromium chloride (CrCl3) supplementation on high-cholesterol fed Japanese quails. Quails were randomly divided into four groups. Group one (n = 25) fed experimental diet only (control; contained basal diet supplemented with 1% cholesterol), group 2 (n = 20) fed experimental diet supplemented with CrCl3 only (400 microg kg(-1) of body weight), groups 3 and 4 (n = 30 per group) were fed experimental diet supplemented with either 0.5% (w/w) of extracted diosgenin plus CrCl3 or pure standard diosgenin (0.5%) plus CrCl3 respectively, for 12 days. Blood samples were collected at days 0 and 12 for measuring levels of lipid profile. The work was carried out at Applied Science University and Amman University, Amman, Jordan during the period from October 2009 through October 2010. The mean levels of total cholesterol (TC) in control quails at d12 was significantly (p < 0.01) increased compare to those at d0. Supplementation of diet with CrCl3 alone or CrCl3 with diosgenin either extracted or pure standard for 12 days showed a significant (p < 0.01) decrease in TC and low density lipoprotein cholesterol (LDL-C) levels as compared to those in the control quails. While, high density lipoprotein cholesterol (HDL-C) increased significantly (p < 0.01) in quails supplemented with diosgenin and CrCl3. At d12, the mean Superoxide Dismutase (SOD) activities in erythrocytes of quails in all supplemented groups was significantly (p < 0.01) increased as compared to those in control group and was more pronounced in erythrocytes of quails supplemented with pure standard diosgenin plus CrCl3. These results indicated that the combined diosgenin and CrCl3 supplementation to high-cholesterol fed quails might induce a protective effect by both regulating lipid and antioxidative damage.     

Comparative Effectiveness of Potential Elicitors of Soybean Plant Resistance Against Spodoptera Littoralis and Their Effects on Secondary Metabolites and Antioxidant Defense System

Gesunde Pflanzen - Cotton leaf worm (Spodoptera littoralis) is considered one of the most destructive agricultural pests in Egypt. It is overcome by the producer by using chemical pesticides, but...     

The path from β-carotene to carlactone, a strigolactone-like plant hormone

Strigolactones, phytohormones with diverse signaling activities, have a common structure consisting of two lactones connected by an enol-ether bridge. Strigolactones derive from carotenoids via a pathway involving the carotenoid cleavage dioxygenases 7 and 8 (CCD7 and CCD8) and the iron-binding protein D27. We show that D27 is a β-carotene isomerase that converts all-trans-β-carotene into 9-cis-β-carotene, which is cleaved by CCD7 into a 9-cis-configured aldehyde. CCD8 incorporates three oxygens into 9-cis-β-apo-10'-carotenal and performs molecular rearrangement, linking carotenoids with strigolactones and producing carlactone, a compound with strigolactone-like biological activities. Knowledge of the structure of carlactone will be crucial for understanding the biology of strigolactones and may have applications in combating parasitic weeds.     

Heavy metals in street and house dust in Bahrain

A total of 106 street and household dusts have been sampled throughout Bahrain and analyzed for Pb, Zn, Cd, Ni and Cr using the atomic absorption spectrophotometric method. The sampling sites were divided into seven categories, including the control site. Results showed that dust samples contained significant levels of the metals studied compared with the control values. The mean values for Pb, Zn, Cd, Ni and Cr in street dust were 697.2, 151.8, 72.0, 125.6 and 144.4 μg g^?1 respectively, whereas for household dust they were 360.0, 64.4, 37.0, 110.2 and 144.7 μg g^?1. These values suggest that motor vehicles form a major source of these metals in dust samples. The values of heavy metals in dust samples in this study were compared with values found in other investigations in various countries. With respect to Ni, elevated concentration could be attributed to smoke from the burning of Kuwait oil fields. Also correlations between metal levels in dust samples for all the metals were investigated. Our results show that heavy metal levels in various sites in Bahrain are similar, which indicate that Bahrain can be considered as one big urban center with high population and traffic density.     

Potential of indigenous antagonistic rhizobacteria in the biological control of Monosporascus root rot and vine decline disease of muskmelon

ABSTRACT

Monosporascus root rot and vine decline (MRVD) of muskmelon, caused by Monosporascus cannonballus, is an economically important disease worldwide. The objectives of this study were to isolate native rhizobacterial strains and to evaluate their ability to promote plant growth and to provide protection against M. cannonballus. Thirty eight native bacterial isolates from the rhizosphere soil of muskmelon and cucumber were screened for their antagonism against M. cannonballus in a dual culture assay. Among them, five isolates viz., Bacillus amyloliquefaciens (B4), Pseudomonas mendocina (B7), Bacillus endophyticus (B10), Pseudomonas resinovorans B11 and P. aeruginosa AT3, identified based on the 16S rRNA gene sequence analysis, showed a significant level of antagonism and the inhibition zone ranged from 5.6 mm to 25.9 mm. Scanning electron microscopic observation of the hyphae of M. cannonballus at the inhibition zone revealed morphological abnormalities including shrinkage, loss of turgidity, pit formation and deformation. These bacterial isolates showed compatibility with one another and with Trichoderma viride. Greenhouse experiments revealed that P. resinovorans B11 was the most effective among the bacterial antagonists in controlling MRVD in melon. When applied as seed treatment and soil application, P. resinovorans B11 reduced the incidence of MRVD by 93.1%, relative to the infected control.