The Effect of Altered Assimilate Allocation and Partitioning Due to PcGA2- Oxidase Overexpression On the Growth and Performance of Creeping Bentgrass (Agrostis stolonifera L.) in Full Sun and Reduced Light.

When grown in shade creeping bentgrass (Agrostis stolonifera L.) exhibits increased stem elongation and reduced tillering. Endogenous gibberellins (GA) are plant hormones that are involved in plant developmental processes including the promotion of shoot elongation. The main objective of this study was to determine the effect of altered assimilate partitioning and allocation due to decreased GA levels on creeping bentgrass growth and performance in light limited environment. Greenhouse studies were performed at The Ohio State University, Columbus, Ohio, USA from August 31 2008 to August 5 2010. Two genetically modified lines, Ax6548 and Ax6549, transformed with CP4 EPSPS and the PcGA2ox genes, and the conventional creeping bentgrass cultivar ‘Crenshaw’ were subjected to full sun (control) and blue polyethylene film with black shade cloth (R:FR 0.7, light reduction 65%). Both transgenic lines exhibited improved quality (color and coverage) as compared to Crenshaw (P=0.05). Growth analysis indicated that when grown in low light both experimental lines partitioned significantly (P=0.05) more dry matter to leaves as compared to Crenshaw. Superior line- Ax6549 maintained the lowest (P=0.05) absolute growth rate both in full sun and shade.