Germin gene expression is induced in wheat (Triticum aestivum L.) leav
es by powdery mildew (Erysiphe graminis f. sp. tritici) infection. Ger
min is a protein marker for early cereal development and is an oxalate
oxidase, an enzyme that catalyzes the conversion of oxalate to CO2 an
d H2O2. The induction of germin gene expression by powdery mildew infe
ction is consistent with the importance of H2O2 to plant defense and i
dentifies a mechanism for the elevation of H2O2 levels in wheat leaves
. Germin mRNA levels increased 2 d after inoculation of seedlings with
powdery mildew and continued to increase throughout an 8-d time cours
e. The increase in accumulation of germin mRNA was accompanied by an i
ncrease in the germin oligomer, which reached maximal levels by d 6. A
n increase in oxalate oxidase activity paralleled germin oligomer accu
mulation. Germin gene expression was induced in a relatively resistant
cultivar (Bobwhite) as well as in a susceptible cultivar (Cheyenne),
suggesting that the induction of germin gene expression is an indicato
r of powdery mildew infection rather than cultivar resistance.