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  • Open access
  • 69 Reads
Fungicide free management of papaya Anthracnose (Colletotrichum gloeosporioides Penz.) disease using combined bio-rationales and bee wax in Organic Agriculture

Papaya (Carica papaya L.) is an economical important orchard crop mainly cultivated in tropical and sub-tropical countries. Due its excellent medicinal value, papaw is recommended to consume daily by medical professionals as fresh fruit. Papaya production is highly being hampered by Papaya Anthracnose disease caused by Colletotrichum gloeosporioides which is inflicting major economic loss of around 40-100 % while cultivation in field, transportation and storage in organic agriculture. An investigation was planned to assess the antifungal capacity of the medicinal plants Spinacia oleracea, Limonia acidissima, Allium sativum, Achyranthes aspera, Calotropis gigantea, Ocimum basilicum, Mukia scabrella, Ficus racemosa , Azadiracta indica , Ocimum tenuiflorum , Lantana camara and Ocimum cinnamonthat, combined with bee wax coating against papaya anthracnose disease. Fifty percent concentrations of botanical were extracted from dried leaves using methanol based solvent extraction method. Two sets of partially ripened non-infected marketable papaya fruits were collected and treated with 50% concentration of botanical extracts and allowed to dry. One set was coated with melted wax by spraying under cool conditions using power sprayer along with non-treated control. These experimental setups were arranged in a complete randomized design with five replicates. Four hours after wax coating, both sets were inoculated with spores of Colletotrichum gloeosporioides. Data on disease incidence, disease severity (0-5 scale), number of days for disease free period, pH, TSS were measured in both sets and ANOVA was performed using SAS software. Duncan’s Multiple Ranges Test (DMRT) was used to determine the least significant differences among the treatments at P <0.05. Results show that disease incidence and severity in Ocimum basilicum + bee wax treated fruits was 0% and 5%, respectively and significant at P <0.05 until 10th day of post-inoculation, thereafter, disease incidence and severity were increased slowly to 15% at 14th day of post-inoculation, but in other treatments and control, disease incidence and severity were varied from 60-80% and 100%, respectively, from 5th day of post-inoculation. Moreover, bee wax-coated papaya fruits showed significantly higher preserved days of maximum 17.047±3.86. Weight loss percentage, pH and TSS were not significantly on par among wax-coated treatments but were significant when compared with wax-free treatments. This study concludes that the combined application Ocimum basilicum + bee wax is a promising alternative to nasty fungicides.

  • Open access
  • 149 Reads
Genetic manipulation of KNAT7 transcription factor enhances saccharification by reducing recalcitrance in the bioenergy crop Populus

The precise role of KNAT7 transcription factors (TFs) in the regulation of secondary cell wall (SCW) biosynthesis of poplars has largely remained unclear as our understanding of KNAT7 is continuously evolving. Through the use of a variety of novel strategies, we can understand how genetic modifications in homologous and heterologous KNAT7 gene expression affect SCW development. The resulting changes in wood properties could in turn affect the saccharification efficiency of lignocellulosic biomass in transgenic poplars. We produced poplar KNAT7 (PtKNAT7) overexpression (PtKNAT7-OE) and RNAi construct (PtKNAT7-AS) for the generation of transgenic poplars. Since the overexpression of homologous genes can potentially result in co-suppression, we also overexpressed Arabidopsis KNAT7 (AtKNAT7-OE) in transgenic poplars. In all our Agrobacterium vector constructs, the expression of KNAT7 transgenes was driven under developing xylem-specific promoter, DX15. The PtKNAT7-AS lines showed a 6% reduction in total lignin content in poplar wood compared to the controls. Syringyl to Guaiacyl lignin (S/G) ratios were significantly increased in all the three transgenic lines from PtKNAT7-OE and PtKNAT7-AS than controls. All transgenic lines including, PtKNAT7-OE, PtKNAT7-AS l, and AtKNAT7-OE wood yielded significantly greater glucose release than controls. Antisense KNAT7 transgenic lines were taller and the stem was thicker than control. These results suggest targeted modification of KNAT7 is achievable in poplar with enhanced functional wall properties without compromising plant growth and productivity. Overall, our results demonstrated that developing xylem-specific genetic alteration of KNAT7 TFs affects the lignification process as well as improving the saccharification efficiency, hence, providing a powerful tool for improving bioethanol production from bioenergy poplar plants.

  • Open access
  • 150 Reads
Overexpression of Arabidopsis Laccase2, Laccase4 and Peroxidase52 in hybrid poplar under developing xylem specific DX15 promoter improves saccharification efficiency in a woody biofuel feedstock

Laccases (LAC) and Peroxidases (PRX) are the key enzymes responsible for the polymerization of a variety of monolignols into lignin. However, little is known about the functions of various members of Lac and Prx gene families in plants. The goal of this research is to understand the biological functions of LAC and PRX in poplar wood formation and to explore how modified Lac and Prx expression affects biomass recalcitrance and growth. This study of heterologous expression of Arabidopsis Lac and Prx genes was conducted in poplars to mitigate the occurrence of co-suppression commonly occurs during the homologous overexpression of highly expressed native genes. To this end, we overexpressed selected Arabidopsis laccase2 (AtLac2), laccase4 (AtLac4), and peroxidase52 (AtPrx52) genes, based on their high level of transcript expression in the differentiating xylem tissues of stems, in hybrid poplar under the developing xylem tissue-specific promoter, DX15 and characterized the transgenic plants for growth phenotypes and recalcitrance efficiency. Transgenic poplar plant lines overexpressing the AtLac2 gene (AtLac2-OE) showed an increase in plant height without a change in biomass yield as compared to the controls. Whereas, AtLac4-OE and AtPrx52-OE transgenic lines did not show any such observable growth phenotypes compared to their respective controls. The total xylem area was decreased by 26% in AtPrx52-OE lines and by 6% in AtLac4-OE lines whereas, the xylem area increased by about 8% in AtLac2-OE lines compared to the controls. Total lignin content was decreased by 2-6% in all the transgenic lines than the controls. This led to an increase in the S/G ratio by 3-10% in all transgenic lines (AtLac2-OE, AtLac4-OE, and AtPrx52-OE) as compared to the controls. The changes in lignin content and S/G ratios in the transgenic poplar lines resulted in a significant increase in the saccharification efficiency as compared to the control plants. Overall, saccharification efficiency was increased by 35-50%, 21-42%, and 8-39% in AtLac2-OE, AtLac4-OE, and AtPrx52-OE transgenic poplar lines respectively, as compared to their controls. Therefore, heterologous expression of specific AtLac and AtPrx genes in poplar species could be one of the potential strategies for increasing saccharification efficiency in woody feedstock for the improved production of bioethanol.

  • Open access
  • 101 Reads
Antimicrobial and In Vivo Antifungal Potentials of Crude and Degummed Citrullus lanatus Seed Oil

Citrullus lanatus (watermelon) seed oil is one of the neglected and underutilized seed oils in Nigeria. This study was aimed at evaluating the therapeutic efficacy of crude and degummed Citrullus lanatus seed oil (CLSO) in the treatment of experimental oral candidiasis induced by Candida albicans in immunosuppressed female albino rats. In vivo antifungal activity of the extracts was analyzed by microbiological and histopathological analyses, along with renal function tests at days 7 and 14 post infection treatments. The observations in the test animal groups were compared with that of control group treated with fluconazole. Treatments with CLSO resulted in significant body weight loss. Also, there was a significant reduction in the kidney fungal burden (cfu/ml/g) of rats treated with CLSO after fourteen days post infection treatment, compared to group 3 (untreated control) rats. Histologically, group 3 (untreated) showed multifocal aggregation and widespread distribution of fungal blastospores appearing singly or in small clusters within the renal parenchyma when compared with CLSO-treated groups, which had minimal fungal blastospores that appeared singly in the renal tissues. Thus, histological data were corroborated with microbiological tests for crude and degummed CLSO, but not for the fluconazole-treated group which showed multifocal and widespread distribution of blastospores at day 14. Furthermore, within the CLSO treatment group, a significant increase in the (plasma) levels of creatinine was observed, while no significant difference in blood urea values was recorded after day 14 post infection study. Histopathological alterations in the kidney was restored to normal. CLSO could be considered as a potential antifungal agent especially the degummed CLSO and could also be employed in the management of weight loss.

  • Open access
  • 58 Reads
Approach to optimization of FRAP methodology for studies based on selected monoterpenes

Terpenes, wide-spread secondary plant metabolites, constitute an important part of natural compounds with various biological activity. Among them are substances revealing antioxidant, calming, antiviral, or analgesic activities. Due to terpenes’ high volatility and their low solubility in water, studies on these compounds prove to be difficult and relevant methodology needs to be adjusted to specific character of compounds being examined. Considering significant influence of iron ions on dementia development, terpenes’ activity towards reduction of Fe3+ should be determined. To date, methodology of FRAP has not been adapted to terpenes, thus, results obtained were unreliable. Taking this fact into account, the aim of the studies was optimization of the method for monoterpenes. Studies included three modifications: 1. slight adjustment of entire FRAP procedure; 2. replacing methanol with other solvents (heptane, butanone, ethyl acetate); 3. addition of Tween 20. Obtained results revealed a significant improvement of reduction activity of selected terpenes (linalool, α-phellandrene, α-terpinene) in studies with Tween 20, whereas replacing methanol with other solvents did not produce expected effects.