The kp4 gene is derived from the genome of a double-stranded RNA
virus (Ustilago Maydis Virus 4, UmV4), which is present in the
tissue of certain fungal strains of corn smut (Ustilago maydis).
The expression of the kp4 gene (KP4, killer protein 4) in Ustilago
maydis cells leads to a reversible inhibition of hyphal growth, but
does not kill off competing strains. It is expected that plants
expressing the KP4 protein are less susceptible to damage caused by
the phytopathogenic fungi Ustilago species. Expression of the kp4
gene is under control of the ubiquitin promoter of the uidA gene
from Zea mays and the t35S terminator of CaMV.
The bar gene derives from Streptomyces hygroscopicus and confers
herbicide resistance against phosphinothricine (Bialaphos). The
gene was used as a transformation marker. Expression of the bar
gene is controlled by the actin promoter of Oryza sativa and the
t35S terminator of CaMV.