Koziol , Elizabeth Katherine , Bever, James .
Weedy and domesticated populations of Helianthus annuus are less drought tolerant and dependant on arbuscular mycorrhizal fungi.
Weedy and invasive plants generally have increased reproductive potential, size, shoot allocation, and growth rate. The increased allocation to growth and fecundity in weedy plants may result from reduced allocation of resources to herbivore defense, drought tolerance, and allocation to fungal symbionts. To investigate whether changes in allocation patterns occur during plant domestication and the evolution of weedy plant populations, we compared the mycorrhizal responsiveness, drought tolerance, and above and below ground growth patterns of 32 populations of Helianthus annuus consisting of 9 native ruderals, 4 US agricultural weeds, 5 Australian invasive and 14 domesticated populations. We found that the domestication of sunflowersis constrained by a trade-off between allocation to growth and drought tolerance. While well watered domesticated plants allocated more resources to above ground structures than native plants, domesticated plants were also significantly less drought tolerant than native plants in terms of leaf wilting, maintaining pot soil moisture, and ability to remain fecund with water stress. This trade-off between growth rate and drought tolerance was also evident in the variation between populations within categories. We also found evidence that drought tolerance is correlated with finer root systems. Comparisons of root characters revealed that the drought tolerant native ruderals had the thinnest diameter and most branched roots, followed by US weedy, Australian invasive and then domesticated lines. Weedy Helianthus annuus plants benefited most from mycorrhizal inoculation by having fewer wilted leaves. Inoculation increased pot soil moisture for US weedy and native populations, but not Australian invasive or domesticated populations. The mycorrhizal response of weedy plants, combined with drought tolerance in between those of native ruderals and domesticates, indicates that weedy plants have adapted to the margins of agricultural lands, which may still harbor undisturbed soil communities but may also have increased access to water.
Log in to add this item to your schedule
1 - Indiana University, Biology, 1001 East Third Street, Bloomington, IN, 47405, USA
Presentation Type: Poster:Posters for Topics
Location: Khorassan Ballroom/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 5:30 PM