Phosphinothricin
acetyltransferase (pat) gene
confers resistance to glufosinate by transforming this herbicide into N-acetyl-l-glufosinate (NAG). The pat gene was inserted in six maize hybrids (Herculex, Agrisure TL, Herculex
Yieldgard, Leptra, Viptera 3, Power Core) as a selectable marker,
and its expression was evaluated by qPCR in comparison with the maize
glufosinate-susceptible cultivar VTPRO. In addition, the levels of
NAG, glufosinate degradation, ammonia accumulation, electron transport
rate (ETR), visual injury, and biomass were also investigated. The
VTPRO, Herculex, Agrisure, and Viptera showed lower pat gene expression, and consequently lower NAG contents and glufosinate
degradation, as well as reduced ETR and biomass accumulation. In contrast,
greater ammonia accumulation and higher visual injury were observed.
The ranking of pat gene expression was Leptra >
Power
Core > Herculex Yieldgard ≫ Herculex > Agrisure TL =
Viptera
3 > VTPRO. This gene expression was proportional to the glufosinate
resistance level observed in each maize hybrid.