Genetic Variations in Leaf Growth Rate in Tall Fescue in Association with Differential Gene Expression Controlling Cell Elongation.

The objective of this study is to determine whether genotypic variations in leaf growth rate in tall fescue are regulated by genes controlling cell elongation. Two cultivars of tall fescue, fast-growing 'K-31' and dwarf type 'Bonsai', plants were examined in hydroponic culture. Leaf elongation rate of 'K-31' was 1.94-fold greater than that for 'Bonsai'. The elongated epidermal cells of 'K-31' were 86% longer than that for 'Bonsai'. The qPCR results indicated that the expression level of one expansin gene in 'K-31', EXPα1, was 82% higher than that for 'Bonsai'. A xyloglucan endotransglucosylase (XET) gene also exhibited higher expression level in ‘K-31’ than in ‘Bonsai’. The genetic variations in EXPα1 and XET expression levels corresponded to those in leaf elongation rate, suggesting that these two genes could play key roles in regulating leaf elongation in tall fescue.