Penetration and Infection Processes of Alternaria brassicicola on Cauliflower Leaf 
 and Alternaria brassicae on Mustard Leaf: A Histopathological Study

Sharma, Pratibha; Deep, Swati; Bhati, Dinesh Singh; Sharma, Mukesh Kumar; Chowdappa, P.

doi:10.3923/ppj.2014.100.111

Cited by 17 publications

(14 citation statements)

References 15 publications

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“…The main mode of penetration by A. brassicicola on cauliflower leaves was reported to be intercellular, with or without forming appressoria, near and through stomata (Sharma et al ., ). In the present study, it was observed that the time needed for appressorium formation depended on individual features of the cabbage phenotype, which determined the morphology and topology of the leaf.…”

Section: Discussionmentioning

confidence: 97%

Infection cycle ofAlternaria brassicicolaonBrassica oleracealeaves under growth room conditions

2018

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Development of the necrotrophic fungus Alternaria brassicicola was evaluated during infection of three cabbage varieties: Brassica oleracea var. capitata f. alba ‘Stone Head’ (white cabbage), B. oleracea var. capitata f. rubra ‘Langedijker Dauer’ (red cabbage) and B. oleracea var. capitata f. sabauda ‘Langedijker Dauerwirsing’ (Savoy cabbage). Following inoculation of cabbage leaves, conidial germination, germ tube growth, and appressorium formation were analysed during the first 24 h of infection. Differences in the dynamics of fungal development on leaves were observed, e.g. approximately 40% of conidia germinated on Savoy cabbage leaves at 4 h post‐inoculation (hpi) while only 20% germinated on red and white cabbage leaves. Leaf penetration on the three cabbage varieties mainly occurred through appressoria, rarely through stomata. Formation of infection cushions was found exclusively on red cabbage. Appressoria were first observed on red cabbage leaves at 6 hpi, and on white and Savoy cabbage leaves at 8 hpi. Conidiogenesis occurred directly from mature conidia at an early stage of fungal development (10 hpi), but later (48 hpi) it occurred through conidiophores. Disease progress and changes in the morphology of leaf surfaces were also observed. At the final 120 hpi measurement point, necroses on all investigated varieties were approximately the same size. Based on detailed light and electron microscopic analyses, an outline of the A. brassicicola infection cycle on B. oleracea leaves under growth room conditions has been proposed. According to the authors’ knowledge, this report represents the most detailed up‐to‐date description of infection of B. oleracea varieties by A. brassicicola.

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Section: Discussionmentioning

confidence: 97%

Infection cycle ofAlternaria brassicicolaonBrassica oleracealeaves under growth room conditions

2018

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“…Simultaneously, we observed the defense responses in host plant leaves: A drastic reorganization of actin networks, deposition of papillae, cell death upon colonization, and limitation of pathogen spread by callose deposition around the infected cell(s). Some authors (Pochon et al 2013;Sharma et al 2014) reported on A. brassicicola infection routes (i.e., leaf penetration modes) depending on a given isolate aggressiveness but agreed on both direct (epidermal) and stomatal penetration possible for the Alternaria spp. in several pathosystems.…”

Section: Discussionmentioning

confidence: 99%

“…in several pathosystems. In particular, Sharma et al (2014) claimed an aberrant behavior of the least aggressive isolate, only attempting the direct penetration. Also, McRoberts and Lennard (1996) diligently tested the host and non-host reactions of susceptible plant materials on an array of Alternaria species; it could be their use of susceptible lines that resulted in comparatively low proportion of stomatal attempted infections.…”

Section: Discussionmentioning

confidence: 99%

Alternaria brassicicola – Brassicaceae pathosystem: insights into the infection process and resistance mechanisms under optimized artificial bio-assay

et al. 2018

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Heavy losses incited yearly by Alternaria brassicicola on the vegetable Brassicaceae have prompted our search for sources of genetic resistance against the pathogen and the resultant disease, dark leaf spot. We optimized several parameters to test the performance of the plants under artificial inoculations with this pathogen, including leaf age and position, inoculum concentration, and incubation temperature. Using these optimized conditions, we screened a collection of 38 Brassicaceae cultigens with two methods (detached leaf and seedlings). Our results show that either method can be used for the A. brassicicola resistance breeding, and that the plant genotype was crucial in determining its response to the pathogen. The bio-assays for A. brassicicola resistance were run under more stringent lab conditions than the field tests (natural epidemics), resulting in identification of two interspecific hybrids that might be used in breeding programs. Based on the results of the biochemical analyses, reactive oxygen species and red-ox enzymes interplay has been suggested to determine the outcome of the plant-A. brassicicola interplay. Confocal microscopy analyses of the leaf samples provided data on the pathogen mode of infection: Direct epidermal infection or stomatal attack were related to plant resistance level against A. brassicicola among the cultigens tested. Further, the microscopic analyses suggested rapid actin network activation of the host cells around the papillas deposited under the pathogen appressorium.

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“…In fact, A. brassicicola seems to be a good model of pathogenic necrotroph when studying the JA mediated defence signaling pathways in plants. An interesting study on how Alternaria brassicicola grows on various leaf surfaces reported that its hyphe penetrated through the epidermis and the stomata in cauliflower, while the fungal growth in mustard was mostly on the leaf surface over the epidermis (Sharma et al, 2014). Similarly, another comparative analysis of infection on the susceptible host (mustard,…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Characterization of Brassica juncea–Alternaria brassicicola interaction and jasmonic acid carboxyl methyl transferase expression

et al. 2015

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Penetration and Infection Processes of Alternaria brassicicola on Cauliflower Leaf and Alternaria brassicae on Mustard Leaf: A Histopathological Study

Cited by 17 publications

References 15 publications

Infection cycle ofAlternaria brassicicolaonBrassica oleracealeaves under growth room conditions

Infection cycle ofAlternaria brassicicolaonBrassica oleracealeaves under growth room conditions

Alternaria brassicicola – Brassicaceae pathosystem: insights into the infection process and resistance mechanisms under optimized artificial bio-assay

Characterization of Brassica juncea–Alternaria brassicicola interaction and jasmonic acid carboxyl methyl transferase expression

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