Effect of PcGA2ox Overexpression On Creeping Bentgrass (Agrostis stolonifera) Photosynthesis and Biomass Accumulation Under Low Light.

Gibberellins are plant hormones that influence large number of developmental processes in plants. The objective of this study was to determine the effect of runner bean GA2-oxidase gene overexpression on creeping bentgrass growth and metabolism under low light conditions. A randomized split-plot greenhouse study with 3 replicates was conducted at The Ohio State University, Columbus, OH from December 2008 to August 2009. One glyphosate-tolerant control: containing the CP4 EPSPS gene, Ar237; two lines transformed with CP4 EPSPS and the runner bean GA2- oxidase gene, Ax6548 and Ax6549; and conventional creeping bentgrass cultivar ‘Crenshaw’ were subjected to full sun (control), black shade cloth (R:FR 1.28, light reduction 70%), photoselective blue polyethylene film (Red:Far Red 0.7, light reduction 25%), and both blue polyethylene film with black shade cloth (R:FR 0.7, light reduction 65%). Photosynthetic rate, chlorophyll fluorescence, chlorophyll levels, and biomass production were measured. Preliminary data showed increased rates of CO₂ uptake and higher maximum quantum yield of PSII in both GA2-ox lines compared to Crenshaw.