Huebner, Cynthia , Minocha, Rakesh .
Stress-induced Response of Microstegium vimineum (Japanese Stiltgrass) to a Low-light Environment.
MICROSTEGIUM vimineum is an invasive C4 grass characterized as shade tolerant. Individual plants of M. vimineum in closed canopy forests tend to be smaller in height and produce fewer chasmogamous flowers unlike populations in high light. We hypothesized that M. vimineum is under stress in shaded environments. Stressed plants respond by increasing leaf cellular putrescine (a common diamine) and amino acids. Microstegium vimineum was grown in controlled environments using field-collected seed and Redi-earth soil mix such that two plants in 10 replicate pots were exposed to every combination of two levels of light, nitrogen, and water for three months (until plants flowered). The high-light treatment (HL) mimicked open, clear sky conditions (1000 - 1700 μmolm-2s-1). The low-light treatment (LL) was 10% of HLís level. The high-nitrogen and high-water treatments had twice as much nitrogen and water as the lower levels. Leaf tissue was analyzed for polyamines and amino acids using high performance liquid chromatography (HPLC) and for ions using inductively coupled plasma (ICP) spectrometry. Results show that cellular levels of free putrescine and several amino acids (e.g. proline) as well as total chlorophyll content were significantly higher while spermidine and exchangeable Ca levels were significantly lower for all LL plants compared to HL plants. Spermidine, a common polyamine, is needed for cell division and development and its levels are tightly regulated under non-stressful conditions. The nitrogen and water treatments by themselves showed no significant differences for putrescine, proline, chlorophyll, spermidine, or Ca, though there were significant treatment interactions. LL plants were significantly smaller (height and stem number) and produced significantly fewer seeds than the HL plants. Thus, LL plants were under stress and using most of their available resources for light fixation instead of for growth.
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1 - NE Research Station, USDA Forest Service, 180 Canfield St., Morgantown, West Virginia, 26505, USA
2 - NE Research Station, USDA Forest Service, 271 Mast Road, P.O. Box 640, Durham, New Hampshire, 03824, USA
Presentation Type: Oral Paper:Papers for Topics
Location: 134/Performing Arts Center
Date: Monday, July 31st, 2006
Time: 11:00 AM