Abstract
Due to premature defoliation, early blight epidemics can cause major yield losses. Large-spore Alternaria species such as A. solani and A. tomatophila have long been recognized as important pathogens responsible for such blight disease in the family Solanaceae and thus represent a serious risk for crop production. Small-spore Alternaria species have also been frequently isolated from plant samples with typical blight symptoms but their incidence as primary pathogens is often controversial. In order to study the diversity of small-spore Alternaria species, 32 isolates were selected from a larger collection of 130 isolates from infected leaves, fruits and stems of tomato from various growing regions of North-West Algeria. Morphological characterization under standard conditions and polymerase chain reaction (PCR) analyses using specific primers to amplify a part of the ITS regions and the 5.8S gene were conducted to confirm their identification as members of the alternata section. They were then examined according to morphological characteristics of conidia and sporulation patterns on potato carrot agar (PCA) and were segregated into three morphological species: A. alternata, A. tenuissima and A. arborescens. Colony type, substrate colour, margin, zonation, pigmentation, colony diameter and conidia production were studied on potato sucrose agar (PSA). Physiological parameters and nutritional requirements of the isolates were also assessed and a data matrix based on cluster analysis and Euclidean distance was constructed. Results of pathogenicity test on tomato showed obvious diversity among the isolates and they could be separated into two groups based on their virulence. The dendrogram based on the influence of cultural, nutritional and physiological characters suggests moderate heterogeneity within the populations of A. alternata and A. tenuissima. The small-spore species formed five clusters that fundamentally paralleled the morphological groupings. However, the results provided no evidence for geographical and pathogenicity clustering of isolates. Key words: Epidemiology, Solanaceae, small-spore Alternaria species, pathogenic variability, cultural characters, physiological diversity.
Highlights
IntroductionPhysiolog gical an nd path hogenic variiability y of sm mall-sp pore Alternarria sp. causin ht of ng leaff bligh
Morpho ologica al, physiolog gical an nd path hogenic variiability y of sm mall-sp pore Alternarria sp. causin ht of ng leaff bligh
The objective of this study was to evaluate the importance of small–spore Alternaria species and to analyze the phenotypic variability within these populations isolated from tomato with early blight symptoms
Summary
Physiolog gical an nd path hogenic variiability y of sm mall-sp pore Alternarria sp. causin ht of ng leaff bligh. Morphologic cal characterrization unde er standard c conditions an nd polymera ase chain reaction (PCR) analyse es using specific primers s to amplify a part of the ITS region ns and the 5.8S gene were condu ucted to con nfirm their id dentification n as membe rs of the altternata secttion. They w were examined according a to o morpholog gical charactteristics of c conidia and sporulation n patterns o on potato carrot agarr (PCA) and were segreg gated into th hree morpho ological spec cies: A. alte ernata, A. ten nuissima and A. arborescens. Its production is ca 10 MQx of which 3.8 MQx is for industrial use
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.