Noor Andryan llsanAbdjad Asih NawangsihAris Tri Wahyudi
8页
查看更多>>摘要：Bacterial Leaf Blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is the most destructive and serious disease causing productivity loss, especially in rice, in Asia. The chemical pesticide usage over a long period of time brings about adversetoxic effect on the potential production of the land and the main consumers of the products. Microbes as biocontrol agents have efficiency and safety for humans and other non-target organisms. They leave small amount or no residue in foods. Soil microbescannot be used directly as biopesticides because common root-colonizers fail to establish on leaves. Actinomycetes are Gram positive bacteria that are known to produce bioactive compound up to 70% of the total compound produced by bacteria, including antimicrobes. Several strains of actinomycetes are known capable of protecting plants against plant disease. The aims of this study were to isolate and screen non-pathogenic phyllosphere actinomycetes of rice which are capable of controlling BLB disease inrice. A total eight isolates are positively capable of controlling Xoo in vitro and four isolates significantly reduce disease severity of BLB. Pellet of STG15, which is the best, showed 25.87% control efficiency of BLB severity at 14 Days After Inoculation (DAI) using Xoo compared to control. Molecular identification based on 16S rRNA gene performed for six isolates with the highest activity showed that they belongs to genus Streptomyces, Actinomadura, Nonomuraea, Micromonospora. Isolate STG 15 whichhas the highest capability to control BLB incidenceis identified as Nonomuraeasp.
查看更多>>摘要：Orchids are one of the important ornamental plants that were cultivated in tropical countries, including in Indonesia. Virus infections has been important limiting factor in orchids cultivation because it could decrease the orchids quality. Odontoglossum ringspot virus (ORSV) is one of the most reported viruses infecting orchids, which spread widely in the world. During 2010-2011 surveys of viral diseases were conducted in Jawa and Bali, Indonesia. The orchids were found infected by virus, showed symptoms of mosaic, mottle, chlorotic, necrotic, streak, wilting leaf and ringspot on leaf surface. Detection with Reverse Transcription-Polymerase Chain Reaction (RT-PCR) showed that only 5 from 88 samples were infected by ORSV with total incidence of 5.7%. Three leaf samples of Phalaenopsis sp., were infected, then called ORSV BOC, ORSV KRB and ORSVTNBB isolates, respectively. The results obtained by amplification of DNA band with 474 bp in length as expression of Coat Protein (CP) gene. Phylogenetic analysis based on nucleotide sequences of CP gene showed that ORSV BOC have similarity to ORSV Germany, whereas, ORSV KRB and ORSVTNBB lead to speciation that possibly to be a new strain. This study was proved that ORSV have entered and spread widely by infected orchids in orchids landscape (nursery), semi-natural forests (botanical gardens) and natural forest (national park) in Java and Bali, Indonesia.
Christopher C. OnyekeGodswill C. AjuzioguSimon C. EzeKevin I. Ugwuoke...
6页
查看更多>>摘要：Screen house experiments were conducted to ascertain the effects of soil amendments with pig excrements/manure at different levels (0 (controls), 10,20,30,40,50 and 601 ha-1) on the management of Meloidogyne javanica at different inoculum densities (0(controls), 2,000 and 4,000 eggs) on the African yam bean. Soil amendment with pig manure significantly (p<0.05) improved on the vegetative growth of African yam bean plants infected with eggs of M. javanica when compared with infected plants but without amendment. The amendment also significantly (p<0.05) suppressed the formation of root galls and egg masses and consequently recorded lower gall and egg mass indices as against the controls. The effect of soil amendments with pig manure on the management of M. javanica on test plants increased with increase in amendment levels. It was also observed that the infectivity of M. javanica increased at a higher inoculums density (4,000 eggs). Generally, it can be concluded that incorporation of pig excrement/manure in African yam bean fields infested with M. javanica would lead to improved growth of plants and also suppress nematode population.
查看更多>>摘要：Background: In Egypt, chocolate spot disease caused by Botrytis fabae Sard, and Botrytis sinerea Pers. is the most serious disease affecting bean. Trichoderma harzianum Rifai is one of the most potent bioagents used for the control of many plant pathogens. This biocontrol agent has not harmful effects on humans, wild life and other beneficial organisms, safe and effective biocontrol agent in both natural and controlled environments that doesn't accumulate in the food chain. Materials and Methods:Theantagonistic effect of T. harzianum against B. fabae was investigated on Potato Dextrose Agar (PDA) medium using dual culture technique. Also the antifungal activity of T. harzianum metabolites was also tested on the linear growth of B. fabae using cellophane method. Scanning electron microscopy was also used to investigate the mycoparasitic nature ofT. harzianum on B. fabae. Results: An overgrowth of T. harzianum on B. fabae was observed, indicating the antagonistic behavior of T. harzianum against B.fabae. A complete reduction in the linear growth of B. fabae was observed indicating the antifungal activity of T. harzianum metabolites. By using the slide culture method, light microscopy observations showed an evidence about the mycoparasitic nature of the tested isolate of T. harzianum on B. fabae. Scanning electron microscopic observations confirmed the mycoparasitic nature of T. harzianum on B. fabae. Conclusion:The above results confirmed the mycoparasitic and aggressive nature of T. harzianum onB. fabae.
查看更多>>摘要：Background and Objective: Groundnut Bud Necrosis Virus (GBNV) (family Bunyaviridae, genus Tospovirus) is an emerging plant viral disease. The GBNV was a very broad host range infecting many economically important crops throughout in India. So the aimof this study is to survey, screening, identification of GBNV infecting onion to know the genetic diversity and compare the sensitivity limit of ELISA, RT-PCR and IC-RT-PCR in GBNV infected onion samples. Materials and Methods:The straw colored, mosaic and necrotic lesions exhibiting by young leaves of onion plants were collected from different locations in South India. The disease samples (No. of samples = 73) were initially screened by DAC-ELISA by using the GBNV coat protein polyclonal antibodies. Total RNA was isolated from the positive ELISA samples and amplified with GBNV coat protein gene specific primers. Comparison of the sensitivity limit of ELISA, RT-PCR and IC-RT-PCR in GBNV infected onion samples. Results: In DAC-ELISA, 50 (68.49%) sampleswere confirmed as GBNV infected from collected onion samples (n = 73) in the field. In RT-PCR, 61 samples (83.56%) were confirmed by RT-PCR method and 68 samples (93.15%) were confirmed by IC-RT-PCR based on the coat protein gene of GBNV. The sequence analysis revealed that the coat protein gene shared 93-100 and 95-100% sequence identity with GBNV at the nucleotide and amino acid levels, respectively. The sensitivity was compared in DAC-ELISA, RT-PCR and IC-RT-PCR showed 10~3,10~5 and 10-6 dilutions,respectively and not observed in healthy onion samples. Conclusion: The IC-RT-PCR was found to be more sensitive than RT-PCR and ELISA for the detection of GBNV.
查看更多>>摘要：Background and Objective: The emergence of unknown pathogens that cause massive wilting of the cashew tree in Magawa, Coast region, Tanzania has caused big turmoil tofamers. Many families are frustrated and have cut down the wilting cashews leaving their farm bear, while others shifted to alternative food crops which has caused unsustainable life due to decrease in their household income and generally increased poverty. This study presents the scientific investigations on the causes of the diseases;gives scientific explanations to related farmers field observations and provides some way forward in mitigating the chaos. Materials and Methods: Field investigations were carried out including face-to-face interview to the farmers. Laboratory investigation involved isolation and characterisation of the pathogen using both morphological and molecular markers as well as pathogenicity test to prove the disease causative agent. Results: Field investigation showed that the wilting disease becomes epidemic within few weeks of its first appearance, leading to complete cashew tree loss especially after rain season. The laboratory investigations and pathogenicity test established the pathogen-causing cashew wilting disease to be Fusarium oxysporum. Conclusion:This is the first study of Fusarium species being associated with cashew wilt disease. The study thus, draws an attention to other cashew growers in the world of the emerging threat of Fusarium wilting diseases to cashew crop.
查看更多>>摘要：Background: This study is about an assessment of plant growth promoter and biocontrol properties of Trichoderma harzianum in onion. Two isolates of T. harzianum one originating from Eco-Ta (South Africa) and the other from a onion field soil (BurkinaFaso) were evaluated for their use as onion growth promoters and their efficiency in protecting onion seedlings against damping-off caused by Fusarium oxysporum and F. solani. Materials and Methods: Trichoderma harzianum was used for coating onion seedswith a conidial suspension concentrated to 107 spores rnL-1 and for directly spraying onion seedbeds with the same conidial suspension. Sowing was done with coated seeds in trays containing a doubly sterilized substrate inoculated or not with Fusarium strains. Non-coated seeds were sowed in the same substrate sprayed with T. harzianum conidial suspension and inoculated or not with Fusarium strains. All trays were kept in greenhouse fori month.Results:Coating the seeds and spraying the seedbeds with theconidial suspension of the two T. harzianum isolates led to a significant increase in the number of living seedlings, seedling length, root length, number of leaves and fresh weight of seedlings 30 days after sowing in sterilized soils. Sowing the T. harzianum coated seeds in soils inoculated with Fusarium led to a significant reduction in seedling damping-off due to the pathogens and improved the growth parameters of seedlings compared with non-coated seeds. Spraying the conidial suspension of T. harzianum isolates on seedbeds inoculated with both Fusarium strains produced the same results, but at a lower intensity than was the case with seed coating. Conclusion: These results reveal that the use of an indigenous isolate of T. harzianum originated from Burkina Faso could be a novel biocontrol strategy against the damping-off of onion seeds in an environmentally sustainable way. This study discusses further development of a simple and accessible method for the mass production and conservation of T. harzianum and the search for an effective and inexpensive sticker for seed coating. An isolate of T. harzianum native to Burkina Faso was shown to improve the germination of onion seeds and to protect seedlings against Fusarium damping-off. This isolate can be exploited in the development of integrated onion crop protection in West Africa.
查看更多>>摘要：Background: Cucumber mosaic virus (CMV) is one of the most important viruses infecting vegetables in the fields throughout the world. Transmission efficiency of CMV could depend on the variability of virus strain but also aphid vector species and/or clones. Materialsand Methods: By sequence analysis, the coat protein gene of CMV strains from different regions revealed that the CMV isolates used for this study belong to the same group. Both CMV strains and Myzus persicae (Sulzer) aphid clones were investigated for their role in viral dispersion by reciprocal tests on Nicotiana tabacum (L.) using the same clone of Myzus persicae towards different CMV strains or using one CMV strain on different Myzus persicae clones. Results: Virus transmission efficiency wasfound to be significantly influenced by selected CMV strains (from 5-30% of transmission rate for identical aphid clone) and also by the selected aphid clones (variation from 15-70% of transmission rate for identical virus strain). Conclusion: The CMV transmission efficiency depends on the variability of virus strain but also aphid vector clones. Combining the variability of CMV transmission rates for both aphid and virus sides, the prediction and modeling of virus spreading seems to be difficult to organize and are closely dependent on the variability of each protagonist-aphid and virus.
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