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MASS APPLICATION OF MECHANO-DWARFING STIMULI TO ARABIDOPSIS FOR MUTANT-SCREEN DEVELOPMENT.  J. A. Montgomery, R.A. Bressan, C.A. Mitchell, Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN.

   Various forms of mechano-stimulation were applied to Arabidopsis thaliana (L.) Heynh. seedlings of the C-24 ecotype in effort to obtain uniform growth reduction compared to undisturbed controls.  Preliminary work investigated effects of static impedance (perforated plates), dynamic compression and flexing (roller), dynamic frictional contact and flexing (brushes), or vibration in both greenhouse and controlled growth environments. Treatments were applied alone or in combination varying intensity, duration, and time of stress application. Treatment effects in both locations were compromised due to interactions of PPF, media, temperature, and nutritional factors. Arabidopsis grown under low PPF (50-55 µmol m^-2 s^-1) using a rockwool growth medium hydrated with 1/4 X Hoagland’s solution grew upright with limited leaf expansion, which increased mechano-stress responsiveness. Low irradiance with different red/far-red wavelength ratios was tested for brush and plate treatments. Hypocotyl elongation and leaf expansion were reduced by twice daily brush or plate treatments. Under fluorescent radiation, brushed seedlings exhibited a 40% reduction in growth relative to undisturbed controls, whereas plate treatments produced a 30% reduction after 6 days of twice-daily treatment. Seedlings grown under fluorescent + incandescent lamps also exhibited stress-induced growth reductions, but stressed seedlings lodged to a greater extent due to more rapid hypocotyl elongation. Temperature and daylength optimization studies are underway.  T-DNA insertional mutant lines will be screened for TCH-gene knockouts using a system that includes low PPF fluorescent lighting, and  twice-daily brush treatment.

(Supported in part by the Laurenz M. Greene Undergraduate Scholarship Program.)

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