Stemphylium lycopersici
(Enjoji) W. Yamam was initially described from tomato and has been reported to infect different hosts worldwide. Sequence analyses of the internal transcribed spacer (ITS) ...regions 1 and 2, including 5.8S rDNA (ITS-5.8S rDNA) and glyceraldehyde-3-phosphate dehydrogenase (
gpd
) gene, random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR), as well as virulence studies were conducted to analyze 46
S. lycopersici
isolates.
Stemphylium lycopersici
isolates used in this study were obtained from diseased tomato (
Solanum lycopersicum
L.), eggplant (
Solanum melongena
L.), pepper (
Capsicum annuum
L.) and lettuce (
Lactuca sativa
L.) from major vegetable growing regions of Malaysia, including the three states of Pahang, Johor and Selangor between 2011 and 2012. Phylogenetic analysis of a combined dataset of the ITS-5.8S rDNA and
gpd
regions indicated that all isolates were clustered in the sub-cluster that comprised
S. lycopersici
, and were distinguished from other
Stemphylium
species. Cluster analyses using the UPGMA method for both RAPD and ISSR markers grouped
S. lycopersici
isolates into three main clusters with similarity index values of 67 and 68 %. The genetic diversity data confirmed that isolates of
S. lycopersici
are in concordance to host plants, and not geographical origin of the isolates. All
S. lycopersici
isolates were pathogenic on their original host plants and showed leaf spot symptoms; however, virulence variability was observed among the isolates. In cross-inoculation assays, the representative isolates were able to cause leaf spot symptoms on eggplant, pepper, lettuce and tomato, but not on cabbage.
Effect of Foliar and Root Application of Silicon Against Rice Blast Fungus in MR219 Rice Variety Abed-Ashtiani, Farnaz, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; Kadir, Jugah-Bin, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; Selamat, Ahmad-Bin, Universiti Putra Malaysia, Serdang, Selangor, Malaysia ...
The plant pathology journal,
06/2012, Letnik:
28, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Rice blast disease caused by Magnaporthe grisea (Hebert) Barr teleomorph is one of the most devastating diseases in rice plantation areas. Silicon is considered as a useful element for a large ...variety of plants. Rice variety MR219 was grown in the glasshouse to investigate the function of silicon in conferring resistance against blast. Silica gel was applied to soil while sodium silicate was used as foliar spray at the rates of 0, 60, 120, 180 g/5 kg soil and 0, 1, 2, 3 ml/l respectively. The treatments were arranged in a completely randomized design. Disease severity and silicon content of leaves were compared between the non-amended controls and rice plants receiving the different rates and sources of silicon. Silicon at all rates of application significantly (α = 0.05) reduced the severity of disease with highest reduction (75%) recorded in treatments receiving 120 g of silica gel. SEM/EDX observations demonstrated a significant difference in weight concentration of silicon in silica cells on the leaf epidermis between silicon treated (25.79%) and non treated plants (7.87%) indicating that Si-fertilization resulted in higher deposition of Si in silica cells in comparison with non-treated plants. Application of silicon also led to a significant increase in Si contents of leaves. Contrast procedures indicated higher efficiency of silica gel in comparison to sodium silicate in almost all parameters assessed. The results suggest that mitigated levels of disease were associated with silicification and fortification of leaf epidermal cells through silicon fertilization.
The compatibility and synergy in efficacy of the termiticide fipronil with a biocontrol agent Metarhizium anisopliae, alone or in combination, against the subterranean termite, Coptotermes ...curvignathus were investigated. Sublethal doses of fipronil were found relatively less detrimental to fungal growth of M. anisopliae local isolates in a compatibility test. The fungus–insecticide bait formulation showed the greatest synergistic effect that increased termite mortality as well as reduced the lethal time at a sublethal dose of 0.05 mg a.i./l fipronil with conidia concentrations of 107 conidia/g bait (χ² = 48.80) at LT50 value of 6.46 days, followed by 108 conidia/gbait (χ² = 5.09) at LT50 value of 4.89 days compared to the use of these control agents alone. The insecticidal stress caused by sublethal fipronil in the formulated bait may weaken the termites and reduce their defence mechanism, which facilitates fungus infection on termites. The observed synergism treatments show the potential for integrated fungus–insecticide control method and need to be further investigated on termite infested oil palm trees.
The genus Pyricularia (anamorph)/Magnaporthe (teleomorph) includes important destructive pathogens causing blast disease on various species from the family Poaceae. Thirty-five Magnaporthe isolates ...were collected from diseased rice plants (variety MR219) in different rice-growing regions of Malaysia, including the five states of Selangor, Penang, Kedah, Kelantan, and Perak between 2010 and 2014. DNA sequence analyses of the internal transcribed spacer (ITS), actin, β-tubulin and calmodulin gene regions, random amplified polymorphic DNA (RAPD) and inter simple sequence repeat (ISSR) analyses were conducted to analyse 35 Magnaporthe isolates. Phylogenetic analysis of the combined dataset confirmed the identification of all isolates as M. oryzae with a high distance from other Magnaporthe (Pyricularia) species. RAPD and ISSR analyses indicated the existence of a relatively low similarity index value among M. oryzae isolates through identification of four main clades. The clustering of RAPD and ISSR analyses demonstrated that there was a correlation between the isolates and their geographical origins.
A new species of Alternaria causing leaf spot of pepper (Capsicum annuum) obtained from the Cameron highlands, Pahang, Malaysia, was determined based on phylogenetic analyses, morphological ...characteristics, and pathogenicity assays. Phylogenetic analyses of combined dataset of the glyceraldehyde-3-phosphate dehydrogenase (gpd), Alternaria allergen a 1 (Alt a1) and calmodulin genes revealed that the new isolates clustered into a subclade distinct from the closely related Alternaria species A. tomato and A. burnsii. The solitary or short chains of conidia resemble those of A. burnsii. However, conidia with long beaks are morphologically similar to A. tomato. Hence, the pathogenic fungus is proposed as Alternaria capsicicola sp. nov. Pathogenicity assays indicated that A. capsicicola causes leaf spot on pepper.
A leaf spot disease was observed on cabbage (Brassica oleracea L. var. capitata) affecting 80% of plants growing in greenhouses and fields in Serdang, Selangor, Malaysia. Symptomatic leaf samples ...were collected from infected plants and isolations made on agar medium. Single-spore isolates from resulting colonies were identified based on cultural and morphological characteristics as Pithomyces chartarum . Morphological identification was confirmed by sequence analysis of the internal transcribed spacer (ITS) regions 1 and 2, including 5.8S rDNA (ITS1-5.8S-ITS2). Pathogenicity tests indicated that P. chartarum causes leaf spot on cabbage. This is the first report of leaf spot caused by P. chartarum on cabbage in Malaysia.
A potculture experiment was carried out to study the effect of calcium applied to the root zone of papaya seedlings (Carica papaya L. cv. Eksotika II) on nutrient uptake and morphological traits ...during 2010-11 at Agro technology Unit, University Agriculture Park (TPU), Universiti Putra Malaysia, Serdang, Selangor. Papaya seedlings established in pots fertigated with different levels of concentrations of recommended nutrient solutions. Three different sources of calcium such as calcium chloride (CaCl2), calcium nitrate Ca (NO3)2 and calcium propionate Ca(C2H5COO)2 in different six concentrations (0, 180, 240, 300, 360 and 420 mg L-1) were added to the root zone at depth of 15 to 25 cm. The addition of calcium to the root zone was started one month after transplanting of seedlings and continued fortnightly for two months. The N, P, K, Ca and Cl content were measured from the leaves during the experiment. Similarly growth observations on stem height, stem diameter, root number, root length and average root diameter were measured one month after transplanting. The results indicate that the N content is higher under calcium nitrate and calcium propionate treatments. However application of calcium through calcium chloride decreased the N content. The potassium (P) content was not influenced under different sources of calcium instead the potassium content decreased with increasing calcium concentration. Furthermore, even though the calcium content in plant was not significantly affected by the different sources of calcium, there were significant differences between control and 300 mg L-1 calcium containing nutrient solution. Among the growth parameters, stem diameter and root length were maximum under the application of 240 and 180 mg L-1 nutrient solution, respectively. However, with the exception of control, the differences for other treatments could not reach the level of significance.
•Streptomyces UPMRS4, a potential biocontrol and bioenhancer agent in rice.•UPMRS4 reduced rice blast disease by 67.9% while maintaining yield attributes.•UPMRS4 increased plant growth and ...up-regulated defence-related genes.
The Streptomyces strain UPMRS4 was selected as a potential biocontrol agent for rice blast disease based on its strong antagonistic activity against Pyricularia oryzae strain UPMPo in vitro. It was further identified as a novel Streptomyces sp. through 16S ribosomal DNA sequence analysis. Biochemical characterization indicated that UPMRS4 was positive for ammonia, urea and siderophore production, as well as amylase, protease and lipase enzymatic tests. Treatment with UPMRS4 was able to reduce 67.9% of disease severity compared with other treatments and able to increase shoot height (15.13%), shoot dry weight (45.75%), leaf surface area (44.6%), root length (48.93), root dry weight (63.25%), number of tillers (42.26%), yield (36.96%), panicle length (15.4%) and the number of spikelet/panicles (29.39%) compared to the control plants at three months after inoculation. The transcript level of chitinase (Cht-1), glucanase (Gns1), pathogenesis-related gene (OsPR1a) and salicylic acid-responsive gene (Oswrky45) were up-regulated during early rice-UPMRS4 interactions. These results suggest that UPMRS4 is a very promising antagonist candidate against P. oryzae which could be developed for sustainable rice blast disease management. To our best knowledge, this is the first study related to the effects of an actinomycete on rice blast disease and plant growth in Malaysia.
•Defense mechanisms in crown tissue of banana as influenced by UVC are elucidated.•UVC induced lignin and phenolic compounds in crown tissue of banana.•UVC caused induction of lignification enzymes ...in crown tissue.•Wall apposition and phenol-storing cells explain the persistence of resistance.
The reduction of crown rot disease observed in UVC-irradiated banana fruit, ‘Berangan’ was associated with activation of the defense response mechanisms, increased peroxidase and polyphenol oxidase activities as well as accumulation of lignin and phenolic compounds in its crown tissue, but not phenylalanine ammonia-lyase activity. Transmission electron microscope micrographs revealed that 0.01kJm−2 UVC retarded the losses of cell compartments and disintegrations of fibril fraction in cell wall structure of the crown tissue. UVC treatment 24h after fungal inoculation induced the accumulation of phenol-storing cells that could create an antimicrobial environment in the host tissue for combating the fungal colonization. Moreover, formation of cell wall lignification and heterogenous matrix of cell wall appositions at site of fungal penetration was clearly observed in UVC-irradiated crown tissue, which otherwise absent in the control crowns. These structures might be important physical barriers that were induced by the irradiation to prevent diffusions of toxin and enzyme from the crown rot-infecting fungi.
PDF
