Biological control of damping-off of Cardamom by the VA mycorrhizal fungus, Glomus fasciculatum

Thomas, Latha; Mallesha, B. C.; Bagyaraj, D. J.

doi:10.1016/s0944-5013(11)80092-3

“…Variation occurs among and within plant-AM funguspathogen systems (Dehne 1982, Ingham 1988, Roncadori 1997. Host genotype (Price et al 1995, Norman et al 1996, pathogen species (Thomas et al 1994), pathogen density (Kaye et al 1984), and AM-fungus species and strain (Davis and Menge 1981, Strobel et al 1982, Diederichs 1987, Vaast et. al 1998 influenced the magnitude and sometimes the direction of AM-fungus effects in the metaanalyses.…”

Section: Discussionmentioning

confidence: 99%

Do Arbuscular Mycorrhizal Fungi Alter Plant-Pathogen Relations?

A.¹

2001

Ecology

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Arbuscular mycorrhizal (AM) fungi colonize roots of terrestrial plants and have been hypothesized to reduce susceptibility or to improve the vigor of hosts challenged by root pathogens. Meta-analysis was used to test whether a broad pattern exists in which AM fungi not only enhance plant growth but fundamentally alter plant-pathogen interactions. Data were gathered from studies published between 1970 and early 1998. In these studies nonmycorrhizal or mycorrhizal plants were untreated or challenged with root-infecting fungal pathogens or nematodes. Effect sizes for AM fungus treatment, pathogen treatment, and their interaction were calculated based on measures of average plant growth, pathogen growth, or AM colonization as reported by authors. AM fungus had a very large positive effect, and pathogens had a very large negative effect on plant growth. However, the interaction of AM fungi and pathogen depended upon the class of pathogen. AM fungi tended to decrease the harmful effects of fungal pathogens but to exacerbate the harmful effects of nematodes.Overall, inoculation with AM fungi had a large negative effect on growth of pathogens, but the outcome for nematodes depended upon mode of feeding. AM fungi harmed sedentary endoparasitic nematodes. AM fungi improved growth of migratory endoparasitic nematodes, but this outcome was not significant in an analysis limited to independent experiments. Reduced growth of pathogens in mycorrhizal plants may indicate increased host resistance. Alternatively, reduced AM colonization in pathogen-treated plants may suggest that rootinfecting organisms compete for resources.Some experiments that did not meet criteria for meta-analysis were analyzed with 2 tests by calculating the proportion of experiments in which authors reported a significant pathogen effect in the absence vs. presence of AM fungi. AM fungi did not alter the effect of fungal pathogens but reduced the proportion of experiments in which nematodes depressed plant growth in a test limited to independent observations. Comparison of frequency distributions of effect sizes suggests that the difference in results for nematodes in the meta-analysis and the 2 tests stems from differences in the AM fungus-plant-pathogen systems examined in each approach rather than a statistical artifact.AM fungi reduced pathogen growth in ϳ50% of studies included in 2 tests, and this effect was similar for fungal vs. nematode pathogens and sedentary vs. migratory nematodes. Fungal pathogens reduced AM fungus growth more frequently than did nematodes. Both AM fungi and pathogens suffered reduced growth in 16% of experiments that assessed reciprocal effects. Reciprocal suppression was more common when the pathogen was a fungus, which may indicate that fungal pathogens are more likely than nematodes to compete with AM fungi.Almost all research on the effects of AM fungi on plant-pathogen relations has examined economically important species, in low-phosphorus soil, in greenhouse or microplot culture. Although these analyses revealed genera...

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“…L'activité mycorhizienne se traduit généralement par une augmentation de la diversité et de l'abondance des microorganismes du sol, notamment parmi les antagonistes de parasites (Linderman 2000;Secilia et Bagyaraj 1987;Thomas et al 1994). Ces modifications de la microflore varient selon les paramètres éco-physiologiques et les souches mycorhiziennes testées, et peut affecter l'ensemble de la microflore ou encore l'une ou l'autre de ses composantes (Andrade et al 1997).…”

Section: Microflore Du Solunclassified

Les mycorhizes : un outil de protection des plantes mais non une panacée

Dalpé

¹

2005

phyto

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Les mycorhizes arbusculaires constituent la symbiose végétale la plus répandue à l’échelle planétaire. Les champignons concernés, regroupés dans le phylum Glomeromycota et distribués sur l’ensemble des écosystèmes, colonisent la majorité des plantes terrestres. Aux avantages bien connus des mycorhizes sur la croissance végétale, s’ajoutent plusieurs bénéfices, notamment pour la survie des plantes, leur biodiversité, l’impact sur la microflore du sol et le potentiel d’agent de réduction des stress tant abiotiques que biotiques. Devant une telle panoplie d’avantages pour les plantes et l’environnement, on pourrait croire que les mycorhizes représentent une panacée à plusieurs problèmes liés à la production et à la protection des végétaux. Le complexe « plante-mycorhize-parasite-environnement » constitue la norme à maintenir ou à retrouver pour assurer la durabilité de l’environnement. Le fonctionnement des mycorhizes comme agent de lutte biologique touche globalement cinq mécanismes d’interaction. Certains concernent directement la plante, soit : 1) une stimulation de croissance par le biais d’un apport nutritif accru et une meilleure santé végétale, 2) une transformation morphologique au niveau racinaire, 3) l’induction ou la suppression de mécanismes de défense, notamment ceux impliquant plusieurs enzymes. D’autres agissent sur le parasite : 4) via une compétition directe avec les champignons mycorhiziens liée à la disponibilité de nutriments et de sites d’infection, et sur la structure et la qualité du sol, par le biais d’une 5) modification de la microflore et de l’augmentation du taux de matière organique.

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“…AM fungi may also increase host resistance (reduce pathogen performance) by stimulating a defense response (Volpin et al 1994, Morandi 1996 or altering root exudations used by pathogens (Graham and Menge 1982). AM fungi are also hypothesized to suppress pathogen growth by competing with pathogens for infection sites or photosynthate (Smith 1988, Muchovej et al 1991, Traquair 1995, or promoting growth of soil microbes that are antagonistic to pathogens (Linderman 1992, Thomas et al 1994).…”

mentioning

confidence: 99%

Do Arbuscular Mycorrhizal Fungi Alter Plant–pathogen Relations?

Borowicz

¹

2001

Ecology

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Arbuscular mycorrhizal (AM) fungi colonize roots of terrestrial plants and have been hypothesized to reduce susceptibility or to improve the vigor of hosts challenged by root pathogens. Meta-analysis was used to test whether a broad pattern exists in which AM fungi not only enhance plant growth but fundamentally alter plant-pathogen interactions. Data were gathered from studies published between 1970 and early 1998. In these studies nonmycorrhizal or mycorrhizal plants were untreated or challenged with root-infecting fungal pathogens or nematodes. Effect sizes for AM fungus treatment, pathogen treatment, and their interaction were calculated based on measures of average plant growth, pathogen growth, or AM colonization as reported by authors. AM fungus had a very large positive effect, and pathogens had a very large negative effect on plant growth. However, the interaction of AM fungi and pathogen depended upon the class of pathogen. AM fungi tended to decrease the harmful effects of fungal pathogens but to exacerbate the harmful effects of nematodes.Overall, inoculation with AM fungi had a large negative effect on growth of pathogens, but the outcome for nematodes depended upon mode of feeding. AM fungi harmed sedentary endoparasitic nematodes. AM fungi improved growth of migratory endoparasitic nematodes, but this outcome was not significant in an analysis limited to independent experiments. Reduced growth of pathogens in mycorrhizal plants may indicate increased host resistance. Alternatively, reduced AM colonization in pathogen-treated plants may suggest that rootinfecting organisms compete for resources.Some experiments that did not meet criteria for meta-analysis were analyzed with 2 tests by calculating the proportion of experiments in which authors reported a significant pathogen effect in the absence vs. presence of AM fungi. AM fungi did not alter the effect of fungal pathogens but reduced the proportion of experiments in which nematodes depressed plant growth in a test limited to independent observations. Comparison of frequency distributions of effect sizes suggests that the difference in results for nematodes in the meta-analysis and the 2 tests stems from differences in the AM fungus-plant-pathogen systems examined in each approach rather than a statistical artifact.AM fungi reduced pathogen growth in ϳ50% of studies included in 2 tests, and this effect was similar for fungal vs. nematode pathogens and sedentary vs. migratory nematodes. Fungal pathogens reduced AM fungus growth more frequently than did nematodes. Both AM fungi and pathogens suffered reduced growth in 16% of experiments that assessed reciprocal effects. Reciprocal suppression was more common when the pathogen was a fungus, which may indicate that fungal pathogens are more likely than nematodes to compete with AM fungi.Almost all research on the effects of AM fungi on plant-pathogen relations has examined economically important species, in low-phosphorus soil, in greenhouse or microplot culture. Although these analyses revealed genera...

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Biological control of damping-off of Cardamom by the VA mycorrhizal fungus, Glomus fasciculatum

Cited by 15 publications

References 7 publications

Do Arbuscular Mycorrhizal Fungi Alter Plant-Pathogen Relations?

Do Arbuscular Mycorrhizal Fungi Alter Plant-Pathogen Relations?

Les mycorhizes : un outil de protection des plantes mais non une panacée

Do Arbuscular Mycorrhizal Fungi Alter Plant–pathogen Relations?

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