An outbreak of leaf spot caused by Stemphylium solani on eggplant in Malaysia.

In 2011, a severe gray leaf spot was observed on aubergine (Solanum melongena) in major aubergine growing areas in Malaysia, including the Pahang, Johor and Selangor states. Disease incidence was >70% in severely infected areas of approximately 150 ha of aubergine greenhouses and fields examined. Symptoms initially appeared as small (1-5 mm in diameter), brownish-black specks with concentric circles on the lower leaves. The specks then coalesced and developed into greyish-brown, necrotic lesions, which also appeared on the upper leaves. Eventually, the leaves senesced and were shed. Fungal colonies were greyish green to light brown, and produced a yellow pigment. Single, muriform, brown, oblong conidia formed at the terminal end of each conidiophore. The conidiophores were tan to light brown and ≤220 µm long. Based on these morphological criteria, 25 isolates of the fungus were identified as Stemphylium solani. Further confirmation of the identification was obtained by molecular characterization. A BLAST search in the NCBI database revealed that the sequence was 99% identical with published ITS sequences for two isolates of Stemphylium solani (Accession Nos. AF203451 and HQ840713). This is thought to be the first report of Stemphylium solani on aubergine in Malaysia

Leaf spot on lettuce (Lactuca sativa) caused by Stemphylium solani, a new disease in Malaysia.

In June 2011, lettuce (Lactuca sativa) plants cultivated in major lettuce growing areas in Malaysia, including the Pahang and Johor states, had extensive leaf spots. In severe cases, disease incidence was recorded to be more than 80%. Symptoms on 50 plants were initially water-soaked spots (1-2 mm in diameter) on leaves, which then became circular spots spreading over much of the leaves. Main lettuce growing areas infected by the pathogen in the aforementioned states were investigated and the pathogen was isolated onto potato dextrose agar. Fourteen isolates were identified as Stemphylium solani based on morphological criteria. To confirm morphological characterization, the DNA of the fungus was extracted from mycelium and PCR was conducted using universal primers ITS5 (5′-GGAAGTAAAAGTCGTAACAAGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′), which amplified the internal transcribed spacer (ITS) region of rDNA. The sequencing result was subjected to BLAST analysis, revealing a 99% similarity to other published sequences in the GenBank database (GenBank accession nos. AF203451 and HQ840713). This is thought to be the first report of Stemphylium solani on lettuce in Malaysia

Alternaria capsicicola sp. nov., a new species causing leaf spot of pepper (Capsicum annuum) in Malaysia

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

Morphological, molecular characterization and pathogenicity of Colletotrichum SPP. isolated from legume crops in Peninsular Malaysia

The genus Colletotrichum is among the most important groups of plant pathogenic fungi worldwide. The ability to accurately diagnose species is vital for the implementation of effective disease control and quarantine measures. Little is known and published about the population, distribution, biology and genetic diversity of Colletotrichum species on grain legumes in Malaysia for disease management practices. It is clear that Colletotrichum truncatum, Colletotrichum dematium and Colletotrichum gloeosporioides were the main species responsible for the anthracnose on grain legumes in Malaysia. Colletotrichum capsici and C. truncatum are unique species, although it has been suggested that C. capsici is a synonym of C. truncatum. Analysis of molecular data from DNA sequences of multigene loci confirmed the identity and differentiation of these species. The majority species isolated in this research were in match with the classical morphological descriptions in culture, with the exception of partly overlapping morphological characters. Regardless of hostorigination,Colletotrichum isolates exhibited different degrees of variability and overlapping in morphological and cultural characteristics. Colletotrichum truncatum is known to have a broad host range on the Fabaceae family and other crops such as cabbage (Brassica chinensis), pepper (Capsicum annuum), tomato (Solanum lycopersicum), eggplant (Solanum melongena) and lettuce (Lactuca sativa). In contrast, the host range of isolates of C. dematium and C. gloeosporioides is limited to cowpea and soybean, respectively, Centrosema pubescens was also a common host.Colletotrichum truncatum was reported as more prevalent in soybean than other legumes grown in Malaysia. Pathogenic isolates were genetically indistinguishable from non-pathogenic isolates. Pathogenicity data supported variability in C. truncatum structure with diversity in the host. The molecular data showed congruence between genetic diversity and host populations. A clear insight of the genetic diversity and relationship of Colletotrichum spp. isolates has now emerged. The data also revealed high genetic diversity dispersed to the smallest scale, at the regional or field level. No apparent geographic effect was observed. The combined data of six genes comprised of 2771 characters after alignment, of which 985 characters were parsimony informative. Parsimony and neighbor-joining analysis produced similar topology and all Colletotrichum isolates were clustered into 3 welldefined clades with high bootstrap support, representing three distinct species. Histone and GAPDH genes contain the most phylogenetically informative characters among examined taxa, suggesting these loci with high number of polymorphic nucleotide site can be used in phylogenetic studies to build highly resolved phylogenies at the intraspecific level and closely related species. ISSR and RAPD markers used to investigate the genetic composition of Colletotrichum species from legumes were able to differentiate the species examined. Molecular polymorphism assessed by RAPD and ISSR revealed a level of molecular variability greater than that characterized using multigene sequence analysis within and among Colletotrichum species. However, the results between markers were congruent, but the effective marker ratio and subsequent to that the number of private alleles was greater with ISSR markers. The species-specific primer pair sets; CTF 5'-TCCCCTAAAAAGGACGTCTCCCG-3',CTR 5'-TCCCTCCGAATCCCAATGCGAGA-3'; CDF 5'-CCTCGGGACGCCCTCC-3', CDR 5'-CCCAATGCGAGGACGTTA-3' and CGF 5'-CAGCTCCGTCGCCCGGA-3', CGR 5'-TGTTTTACGGCAGGAGTC-3' targeting on ITS-rDNA were designed to use in PCR detection assay for C. truncatum, C. dematium and C. gloeosporioides,respectively. Species specificity of the primers was confirmed by successful detection of Colletotrichum spp. from infected legume plants, and the absence of DNA amplified products from other Colletotrichum species and divergent genus of the fungi. The results of sexual compatibility tests and genetical analysis showed the heterothallic nature of Glomerella truncata. In all the compatible crosses, perithecia, asci and ascospore morphologies were similar to those described earlier. However, the sexual reproduction in C. truncatum has only been observed under laboratory conditions, and has never been reported in the field. The results indicated the intrinsic potential of C.truncatum for sexual reproduction by producing perithecia under natural conditions

Phytochemical Properties of Mentha longifolia L. Essential Oil and its Antimicrobial Effects on Staphylococcus Aureus

Background & Aim: Due to the side effects of chemical and synthetic preservatives, consumers have recently become more eager to use foods containing natural preservatives from plants, animals and microbial sources. In the present study, biochemical composition and antibacterial effects (MIC) of Mentha longifolia L. essential oil against Staphylococcus aureus have been evaluated. Methods: In this experimental study, the biochemical composition and antibacterial prosperities of this essential oil was determined by the Gas chromatography/ mass spectrophotometer (GC/MS) and micro dilution method respectively. The morphological and membrane changes of the bacterial cell under the effect of this essential oil were evaluated by transmission electron microscopy. The collected data was analyzed by the SPSS software using ANOVA. Results: The chemical analysis of the essential oil by Gas chromatography/ mass spectrophotometer (GC/MS) revealed the presence of 22 substances (95.30%), mainly including Pulegon (31.54%), 1,8 Cineol (15.89%), Menthoforan (11.8%) and Cis- Isopulegon (9.74%). Minimum inhibitory concentration of the essential oil determined under different temperature and pH values showed to be in the range of 75-1200 µg/ ml. Conclusion: The MIC results and membrane cell damage observed in the electron microscopy evaluation indicated that this essential oil have a high antibacterial activity. Therefore, this essential oil can be combined with other agents for the preservation of foods against pathogenic and toxigenic microorganisms

The Plant Pathology Journal Genetic Diversity and Differentiation of Colletotrichum spp. Isolates Associated with Leguminosae Using Multigene Loci, RAPD and ISSR

Genetic diversity and differentiation of 50 Colletotrichum spp. isolates from legume crops studied through multigene loci, RAPD and ISSR analysis. DNA sequence comparisons by six genes (ITS, ACT, Tub2, CHS-1, GAPDH, and HIS3) verified species identity of C. truncatum, C. dematium and C. gloeosporiodes and identity C. capsici as a synonym of C. truncatum. Based on the matrix distance analysis of multigene sequences, the Colletotrichum species showed diverse degrees of intera and interspecific divergence (0.0 to 1.4%) and (15.5-19.9), respectively. A multilocus molecular phylogenetic analysis clustered Colletotrichum spp. isolates into 3 well-defined clades, representing three distinct species; C. truncatum, C. dematium and C. gloeosporioides. The ISSR and RAPD and cluster analysis exhibited a high degree of variability among different isolates and permitted the grouping of isolates of Colletotrichum spp. into three distinct clusters. Distinct populations of Colletotrichum spp. isolates were genetically in accordance with host specificity and inconsistent with geographical origins. The large population of C. truncatum showed greater amounts of genetic diversity than smaller populations of C. dematium and C. gloeosporioides species. Results of ISSR and RAPD markers were congruent, but the effective maker ratio and the number of private alleles were greater in ISSR markers

Genetic Diversity and Differentiation of Colletotrichum spp. Isolates Associated with Leguminosae Using Multigene Loci, RAPD and ISSR

Genetic diversity and differentiation of 50 Colletotrichum spp. isolates from legume crops studied through multigene loci, RAPD and ISSR analysis. DNA sequence comparisons by six genes (ITS, ACT, Tub2, CHS-1, GAPDH, and HIS3) verified species identity of C. truncatum, C. dematium and C. gloeosporiodes and identity C. capsici as a synonym of C. truncatum. Based on the matrix distance analysis of multigene sequences, the Colletotrichum species showed diverse degrees of intera and interspecific divergence (0.0 to 1.4%) and (15.5–19.9), respectively. A multilocus molecular phylogenetic analysis clustered Colletotrichum spp. isolates into 3 well-defined clades, representing three distinct species; C. truncatum, C. dematium and C. gloeosporioides. The ISSR and RAPD and cluster analysis exhibited a high degree of variability among different isolates and permitted the grouping of isolates of Colletotrichum spp. into three distinct clusters. Distinct populations of Colletotrichum spp. isolates were genetically in accordance with host specificity and inconsistent with geographical origins. The large population of C. truncatum showed greater amounts of genetic diversity than smaller populations of C. dematium and C. gloeosporioides species. Results of ISSR and RAPD markers were congruent, but the effective maker ratio and the number of private alleles were greater in ISSR markers