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Harvard Forest Symposium Abstract 2012

• Title: Predicting population-level changes in ragweed (Ambrosia artemisiifolia L.) pollen production and pollen allergen content in response to elevated carbon dioxide.
• Primary Author: Jennifer Albertine (University of Massachusetts at Amherst)
• Additional Authors: Gaurav Dhawan (University of Massachusetts ); Michael Muilenberg (University of Massachusetts ); Christine Rogers (University of Massachusetts at Amherst); Kristina Stinson (University of Massachusetts - Amherst )
• Abstract:

  Common ragweed, a native North American plant, produces highly allergenic pollen. Assessing plant response to predicted levels of carbon dioxide (CO2) is a priority for understanding climate change effects on human health. CO2 is known to have a stimulatory effect on ragweed pollen production. It has also been shown to increase the pollen Amb a1 protein content, which is responsible for the allergic response in humans. However, it is not well known whether plants from environmentally distinct populations respond differently to elevated carbon dioxide. Ecotypic variation in CO2 response was tested by exposing plants from 24 populations across a latitudinal gradient in the northeast United States to three levels of CO2: 400 ppm, 600 ppm, and 800 ppm. The objective of the study was to test for differences among ecotypes in 1) allocation to reproduction, specifically male flowers, 2) amount of pollen produced per male flower weight, and 3) levels of Amb a 1 protein in pollen grains. Wild- collected seeds from each population were planted in pots in outdoor growth chambers and evaluated weekly for phenological data. Experimental design of 4 replications of each of the 3 carbon dioxide levels and 4 replications of the 24 populations within each chamber resulted in assessment of 1,152 plants. At the onset of flowering, clear plastic bags were placed over a minimum of three male inflorescences per plant to collect the pollen. The bags and pollen were removed after the flowers released pollen and were placed in a -80°C freezer. The proteins will be extracted from the pollen and assayed via ELISA to determine the amount of Amb a 1 protein per pollen grain. The number of pollen grains released per flower weight will also be assessed. We will then be able to determine the total amount of pollen released from each plant. This information can then be used by other researchers in this project to determine future allergy hot spots in northeast US.
  
  
  
  
  
  

• Research Category: Ecological Informatics and Modelling
  Large Experiments and Permanent Plot Studies