Presentation Title

Linking mycorrhizal colonization to floral rewards and reproductive success in highbush blueberry

Project Collaborators

Dr. Alison Brody (Faculty mentor), Joanna Santoro (Undergraduate Student Collaborator), Erin O'Neill (Graduate Student Mentor)

Abstract

Linking mycorrhizal colonization to floral rewards and reproductive success in highbush blueberry, Vaccinium corymbosum

My research outlines the background, methodology, and preliminary results of my work investigating the effects of mycorrhizal fungi on floral characteristics of Highbush Blueberry. I ask whether the degree of colonization with mycorrhizal fungi is associated with (1) pollen quantity, (2) nectar quantity, (3), nectar quality, and (3) plant fitness, and I hypothesize that mycorrhizal fungi may have indirect effects on host plant fitness by influencing the quantity and quality of host plant floral rewards.

Background:

Mycorrhizal fungi colonize blueberry plant roots where they are partners in a mutualistic exchange known as mycorrhiza, where fungi provide nutrients and water to the plant and in return receive energy-storing photosynthetic products (Fellbaum et al. 2012). Colonization with mycorrhizal fungi can lead to increased effort into floral traits important to pollinators, such as flower and inflorescence number (Brody et al 2019). Inoculation is also known to influence pollen and nectar production in summer squash and tomatoes (Lau et al. 1995, Poulton 2002). For multiple species of annual plants, pollinators prefer inoculated plants over non-inoculated plants due to the mycorrhizal-enhanced floral display and rewards (Gange and Smith 2005), and increased bee visitation is known to increase seed production, fruit yield and fruit size (Nicholson and Ricketts 2019, Courcelles et al. 2013). My research seeks evidence that mycorrhiza in highbush blueberry increases seed and berry production by increasing the quantity and quality of floral rewards and subsequent pollinator visitation.

Methods:

Study plants consist of 200 highbush blueberry plants at Waterman Berry Farm in Johnson, VT, as well as 100 plants at the Aiken Forestry Sciences Laboratory at UVM. Half of the plants were inoculated with mycorrhizal fungi, while half were left non-inoculated. During the blooming period in May, 2020, I collected pollen and nectar samples from flowers after they have been bagged for 24 hours to block pollinator access to flowers. I measured pollen quantity by collecting the anthers of the bagged flowers into a microcapillary tube, vortexing them in the lab to allow pollen to be released, and counting the number of grains per flower. I measured the volume of extracted nectar in these same bagged flowers using a microcapillary tube and quantified their sugar content using a hand-held refractometer (Kearns and Inouye, 1993). During the fruiting period, I recorded the fruit set, berry size and sugar content, and the number of fertilized and unfertilized seeds in each berry. To determine fungal colonization, I stained root samples with trypan blue dye and vinegar (Vierheilig et al. 1998) and counted the proportion of cells in each sample containing fungal structures using microscopy (McGonigle et al. 1990). All variables will be correlated to fungal colonization with an analysis of covariance to determine significant relationships between colonization and floral traits important to pollinators.

Significance:

The interaction between plants, fungi, and pollinators is relevant to many natural and agricultural systems. Evidence linking a plant's belowground fungal interactions to their pollinator rewards and thus their aboveground pollinator interactions would expand the frontiers of literature on mycorrhizal ecology. From an agricultural standpoint, a better understanding of the permanence of inoculation will inform its cost-effectiveness as a management technique, as seedling inoculation with mycorrhizal fungi may decrease the need for synthetic fertilizer. Data on pollen limitation can provide a measurement of plant response to declining bee populations, which is instrumental when planning for conservation of native bee populations. Finally, if plants with greater fungal colonization better attract pollinators, then native bee population decline may constitute a selective pressure for plants to increase investment in their fungal partnerships.

References:

  • Brody, A. et al., 2019. Am. J. Bot., 106, 1412-1422.

  • Courcelles, D. et al., 2013. J Appl Entomol, 137, 693-701.

  • Fellbaum, C. et al., 2012. Plant Signal Behav, 7, 1509-1512.

  • Gange, A. and A. Smith, 2005. Ecol Entomol, 30, 600-606.

  • Kearns, C., and D. Inouye., 1993. U of Colorado, Print.

  • Lau, T. C. et al., 1995. Plant Cell and Environment, 18, 169–177.

  • McGonigle, T. et al., 1990. New Phytol, 115, 495-501.

  • Nicholson, C., and T. Ricketts. 2019. Agric Ecosys Environ, 272, 29-37.

  • Ollerton, J. et al., 2011. Acta Oecol, 120, 321-326.

  • Palmer‐Young, E. et al., 2019. Ecological Monographs, 89, e01335.

  • Poulton, L. et al., 2002. New Phytologist, 154, 255–264.

  • Vierheilig, H. et al., 1998. Appl Environ Microbiol, 64, 5004.

Primary Faculty Mentor Name

Alison Brody

Graduate Student Mentors

Erin O'Neill

Status

Undergraduate

Student College

College of Arts and Sciences

Program/Major

Environmental Sciences

Primary Research Category

Biological Sciences

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Linking mycorrhizal colonization to floral rewards and reproductive success in highbush blueberry

Linking mycorrhizal colonization to floral rewards and reproductive success in highbush blueberry, Vaccinium corymbosum

My research outlines the background, methodology, and preliminary results of my work investigating the effects of mycorrhizal fungi on floral characteristics of Highbush Blueberry. I ask whether the degree of colonization with mycorrhizal fungi is associated with (1) pollen quantity, (2) nectar quantity, (3), nectar quality, and (3) plant fitness, and I hypothesize that mycorrhizal fungi may have indirect effects on host plant fitness by influencing the quantity and quality of host plant floral rewards.

Background:

Mycorrhizal fungi colonize blueberry plant roots where they are partners in a mutualistic exchange known as mycorrhiza, where fungi provide nutrients and water to the plant and in return receive energy-storing photosynthetic products (Fellbaum et al. 2012). Colonization with mycorrhizal fungi can lead to increased effort into floral traits important to pollinators, such as flower and inflorescence number (Brody et al 2019). Inoculation is also known to influence pollen and nectar production in summer squash and tomatoes (Lau et al. 1995, Poulton 2002). For multiple species of annual plants, pollinators prefer inoculated plants over non-inoculated plants due to the mycorrhizal-enhanced floral display and rewards (Gange and Smith 2005), and increased bee visitation is known to increase seed production, fruit yield and fruit size (Nicholson and Ricketts 2019, Courcelles et al. 2013). My research seeks evidence that mycorrhiza in highbush blueberry increases seed and berry production by increasing the quantity and quality of floral rewards and subsequent pollinator visitation.

Methods:

Study plants consist of 200 highbush blueberry plants at Waterman Berry Farm in Johnson, VT, as well as 100 plants at the Aiken Forestry Sciences Laboratory at UVM. Half of the plants were inoculated with mycorrhizal fungi, while half were left non-inoculated. During the blooming period in May, 2020, I collected pollen and nectar samples from flowers after they have been bagged for 24 hours to block pollinator access to flowers. I measured pollen quantity by collecting the anthers of the bagged flowers into a microcapillary tube, vortexing them in the lab to allow pollen to be released, and counting the number of grains per flower. I measured the volume of extracted nectar in these same bagged flowers using a microcapillary tube and quantified their sugar content using a hand-held refractometer (Kearns and Inouye, 1993). During the fruiting period, I recorded the fruit set, berry size and sugar content, and the number of fertilized and unfertilized seeds in each berry. To determine fungal colonization, I stained root samples with trypan blue dye and vinegar (Vierheilig et al. 1998) and counted the proportion of cells in each sample containing fungal structures using microscopy (McGonigle et al. 1990). All variables will be correlated to fungal colonization with an analysis of covariance to determine significant relationships between colonization and floral traits important to pollinators.

Significance:

The interaction between plants, fungi, and pollinators is relevant to many natural and agricultural systems. Evidence linking a plant's belowground fungal interactions to their pollinator rewards and thus their aboveground pollinator interactions would expand the frontiers of literature on mycorrhizal ecology. From an agricultural standpoint, a better understanding of the permanence of inoculation will inform its cost-effectiveness as a management technique, as seedling inoculation with mycorrhizal fungi may decrease the need for synthetic fertilizer. Data on pollen limitation can provide a measurement of plant response to declining bee populations, which is instrumental when planning for conservation of native bee populations. Finally, if plants with greater fungal colonization better attract pollinators, then native bee population decline may constitute a selective pressure for plants to increase investment in their fungal partnerships.

References:

  • Brody, A. et al., 2019. Am. J. Bot., 106, 1412-1422.

  • Courcelles, D. et al., 2013. J Appl Entomol, 137, 693-701.

  • Fellbaum, C. et al., 2012. Plant Signal Behav, 7, 1509-1512.

  • Gange, A. and A. Smith, 2005. Ecol Entomol, 30, 600-606.

  • Kearns, C., and D. Inouye., 1993. U of Colorado, Print.

  • Lau, T. C. et al., 1995. Plant Cell and Environment, 18, 169–177.

  • McGonigle, T. et al., 1990. New Phytol, 115, 495-501.

  • Nicholson, C., and T. Ricketts. 2019. Agric Ecosys Environ, 272, 29-37.

  • Ollerton, J. et al., 2011. Acta Oecol, 120, 321-326.

  • Palmer‐Young, E. et al., 2019. Ecological Monographs, 89, e01335.

  • Poulton, L. et al., 2002. New Phytologist, 154, 255–264.

  • Vierheilig, H. et al., 1998. Appl Environ Microbiol, 64, 5004.