Benomyl inhibits phosphorus transport but not fungal alkaline phosphatase activity in a <i>Glomus</i>–cucumber symbiosis

Larsen, John; Thingstrup, I.; Jakobsen, Iver; Rosendahl, Søren

doi:10.1111/j.1469-8137.1996.tb04518.x

Cited by 55 publications

(31 citation statements)

References 26 publications

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“…There are several possible reasons to explain why trees did develop P deficiency : (1) trees were planted from the commercial nursery with stored P ( 0n20 % leaf P) that was re-allocated for growth ; (2) root systems had pre-established mycorrhizal colonization when transplanted, and even though further development and activity was inhibited by benomyl, some mycorrhizal-mediated uptake of P occurred even at low P supply ; (3) slow-growing perennial Citrus on the four rootstocks had a relatively low P demand compared with supply of P that the expanding root system and mycorrhiza hyphal network had access to from the soil volume ; (4) trees were sufficient in nutrient content and otherwise well-watered and fertilized with other macronutrients and micronutrients ; or (5) soil-water status and nutrient availability in the low P-fixing Candler fine sand was not as restrictive to diffusion and mass flow of P as might be expected in finer textured soils of higher buffering capacity. The second possibility is supported by studies that indicate benomyl inhibited P uptake, transport and possibly transfer through the plantmycorrhizal fungus interface (Sukarno et al, 1993(Sukarno et al, , 1996, but benomyl did not reduce fungal alkaline phosphatase activity of G. caledonium colonizing cucumber (Larsen et al, 1996). This raises the possibility that different mycorrhizal species in the soil population vary in their sensitivity to benomyl.…”

Section: supporting

confidence: 59%

“…This reduction in P acquisition had no negative effect on growth of trees because tissue P status never dropped below the critical level of leaf P for citrus (0n10 %) during this 27-month study. Adequate P status of citrus trees was maintained with or without P fertilization and despite benomyl inhibition of extraradical and intraradical activity of mycorrhizas (Hale & Sanders, 1982 ;Larsen et al, 1996 ;Sukarno, Smith & Scott, 1993. There are several possible reasons to explain why trees did develop P deficiency : (1) trees were planted from the commercial nursery with stored P ( 0n20 % leaf P) that was re-allocated for growth ; (2) root systems had pre-established mycorrhizal colonization when transplanted, and even though further development and activity was inhibited by benomyl, some mycorrhizal-mediated uptake of P occurred even at low P supply ; (3) slow-growing perennial Citrus on the four rootstocks had a relatively low P demand compared with supply of P that the expanding root system and mycorrhiza hyphal network had access to from the soil volume ; (4) trees were sufficient in nutrient content and otherwise well-watered and fertilized with other macronutrients and micronutrients ; or (5) soil-water status and nutrient availability in the low P-fixing Candler fine sand was not as restrictive to diffusion and mass flow of P as might be expected in finer textured soils of higher buffering capacity.…”

Section: mentioning

confidence: 99%

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Field evidence for the carbon cost of citrus mycorrhizas

Graham

Eissenstat

1998

New Phytologist

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Mycorrhizas can produce negative crop responses when phosphorus availability is sufficient in agricultural soils because the fungi are of no benefit in nutrient acquisition yet continue to colonize roots and invoke parasitic costs. Benomyl fungicide was used to test this prediction in the field by limiting mycorrhizal colonization of 2-yr-old Valencia orange trees (Citrus sinensis (L.) Osbeck) on four rootstocks of varying mycorrhizal dependency in Pdeficient soil fertilized with and without phosphate. No known fungal pathogens of citrus roots controlled by benomyl were present on the trees or in the field soil. Young trees with or without P fertilization and benomyl treatment remained sufficient in P ( 0n10 % leaf P) throughout the 27-month study. Root zone drenches of benomyl reduced mycorrhizal colonization and leaf P status of Valencia orange trees on the three slower-growing rootstocks, trifoliate orange (Poncirus trifoliata (L. ) Raf.), Swingle citrumelo (Citrus paradisi Macf.iP. trifoliata) and sour orange (Citrus aurantium L.), for the duration of three growing seasons. Benomyl affected root colonization and P status of trees on the faster-growing rootstock, Volkamer lemon (Citrus volkameriana Tan. and Pasq.), less than for trees on the slower-growing rootstocks and the effects were sustained for only two seasons. The shorter duration of benomyl effect for trees on Volkamer lemon rootstock compared with the slower-growing rootstocks was explained by the loss of inhibition of mycorrhizal activity when roots grew out of the drench zone and mycorrhizas were no longer in direct contact with the fungicide. Benomyl treatment increased growth rate of Valencia orange on the slow-growing rootstocks from 5 to 17 % after three seasons, and from 2 to 9 % on Volkamer lemon rootstock after two seasons compared with the non-benomyl treated trees. The benomyl effect was attributed to reduction of costs of root colonization over time, and consequently, a greater availability of carbon assimilate for shoot growth of trees. Since mycorrhizal fungi are ubiquitous in fertilized agricultural soils and obligate biotrophs on the roots of most crop species, these results indicate a need to further investigate whether negative growth responses of P-sufficient plants in the field occur because mycorrhizal fungi are no longer behaving as mutualists.

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Section: supporting

confidence: 59%

Section: mentioning

confidence: 99%

Field evidence for the carbon cost of citrus mycorrhizas

Graham

Eissenstat

1998

New Phytologist

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“…Although benomyl often decreases arbuscular mycorrhizal function more than its colonization of roots (Larsen et al, 1996), no evidence was found for an impact on ericoid mycorrhizal function. The isotopic composition of leaf N (δ"&N) of V. uliginosum was unchanged by benomyl addition (Fig.…”

Section: Effects Of Benomyl On Availability Of Soil Nutrients Soil Mmentioning

confidence: 76%

Differential responses of grass and a dwarf shrub to long‐term changes in soil microbial biomass C, N and P following factorial addition of NPK fertilizer, fungicide and labile carbon to a heath

et al. 1999

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Microbial immobilization may decrease the inorganic nutrient concentrations of the soil to the extent of affecting plant nutrient uptake and growth. We have hypothesized that graminoids with opportunistic nutrient-acquisition strategies are strongly influenced by nutrient limitation imposed by microbes, whereas growth forms such as dwarf shrubs are less affected by the mobilization-immobilization cycles in microbes. By adding NPK fertilizer, labile C (sugar) and fungicide (benomyl) over a 5 yr period in a fully factorial design, we aimed to manipulate the sink-source potential for nutrients in a non-acidic heath tundra soil. After 2 yr, N and P accumulated in the microbial biomass after fertilization with no change in microbial C, which suggests that nutrients did not limit microbial biomass growth. After 5 yr, microbial C was enhanced by 60 % in plots with addition of labile C, which points to C-limitation of the microbial biomass. Microbial biomass N and P tended to increase following addition of labile C, by 10 and 25 %, respectively. This caused decreased availability of NH % + and P, showing close microbial control of nutrient availability. The most common graminoid, Festuca ovina, responded to fertilizer addition with a strong increase, and to labile C addition with a strong decrease in cover, providing the first direct field evidence that nutrient limitation imposed by immobilizing microbes can affect the growth of tundra plants. Also in support of our hypothesis, following addition of labile C the concentrations of N and K in leaves and that of N in roots of F. ovina decreased, whilst the demand of roots for P increased. In contrast, the most common dwarf shrub, Vaccinium uliginosum, was only slightly sensitive to changes in resource availability, showing no cover change after 4 yr addition of labile C and fertilizer, and little change in leaf nutrient concentrations. We suggest that the differential responses of the two growth forms are due to differences in storage and nutrient uptake pathways, with the dwarf shrub having large nutrient storage capacity and access to organic forms of N through its mycorrhizal association. While the fungicide had no effect on ericoid mycorrhizal colonization of roots or symbiotic function inferred from plant "&N natural abundance, it decreased microbial biomass C and N after 2 yr. Throughout the fifth season, the availability of soil NO $ − and inorganic P was decreased with no change in microbial biomass C, N or P, suggesting a negative impact of benomyl on N and P mineralization.

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“…The use of root colonization levels as a surrogate measure of mycorrhizal activity may also result in overestimation of the capacity of the AM association to enhance P uptake. Larsen et al (1996) showed that hyphal P-uptake was inhibited when benomyl was applied to an established hyphal network in soil.…”

Section: Discussionmentioning

confidence: 99%

Arbuscular mycorrhizas influence plant diversity and community structure in a semiarid herbland

2002

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Summary• The contribution of arbuscular mycorrhizas (AM) to plant community structure and diversity is reported here in an annual herbland in southern Australia.• Mycorrhizal colonization was reduced in field plots by applying the fungicide benomyl as a soil drench. The mycorrhiza-responsiveness of plant species was assessed in intact soil cores containing the indigenous AM fungi and in a pot experiment using an isolate of Glomus mosseae .• Glasshouse experiments showed that Medicago minima, Vittadinia gracilis and Velleia arguta were highly mycorrhiza-responsive, Salvia verbenaca became colonized but exhibited no growth response to AM, and Carrichtera annua remained uncolonized. There was no change in plant species richness in mycorrhizasuppressed field plots but diversity increased owing to an increase in evenness. Treatment had no effect on community productivity and therefore there was no relationship between mycorrhizal effects on diversity and productivity.• Mycorrhizal responsiveness was not a good predictor of species response to suppression of AM in the field. The mycorrhiza-responsive species V. gracilis and V. arguta were not affected by reduced mycorrhizal colonization in fungicide-treated plots, suggesting that competition from the mycorrhiza-responsive dominant M. minima offset the benefits of mycorrhizal association for these species.

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Benomyl inhibits phosphorus transport but not fungal alkaline phosphatase activity in a Glomus–cucumber symbiosis

Cited by 55 publications

References 26 publications

Field evidence for the carbon cost of citrus mycorrhizas

Field evidence for the carbon cost of citrus mycorrhizas

Differential responses of grass and a dwarf shrub to long‐term changes in soil microbial biomass C, N and P following factorial addition of NPK fertilizer, fungicide and labile carbon to a heath

Arbuscular mycorrhizas influence plant diversity and community structure in a semiarid herbland

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