Partial characterization of potato F0F1-ATPase gamma-subunit cDNA and its regulation during fungal infection and elicitor treatment

Mitochondrial F0F1‐ATP synthase from dicotyledonous plants contains six different subunits named α, β, Γ, Δ, Δ′ and ɛ. A key subunit in the coupling mechanism is the Γ‐subunit, which appears as a single copy in the complex interacting with multiple α and β subunits that contain the catalytic sites. One 0.8‐kb potato cDNA clone sharing 88% homology with the 3′‐end of sweet potato Γ‐ATPase has been isolated by reverse transcriptase‐polymerase chain reaction (RT‐PCR) amplification from potato leaves infected with the pathogenic fungus Phytophthora infestans. Northern blot experiments revealed that the potato Γ‐subunit mRNA level increased 2‐ and 3‐fold in infected potato leaves 48 and 72 h after infection, respectively. The enzyme activity of F0F1‐ATPase was 2‐fold higher in 48‐h‐infected potato leaves than in mock‐inoculated ones. The fungal elicitors eicosapentanoic acid (EPA) and glucans from P. infestans cell wall were used in induction experiments on potato tuber discs. After 48 h of treatment, the Γ‐ATPase mRNA levels were respectively increased by 1.8, 1.4 and 2.2‐fold in EPA, glucans and EPA plus glucan treatments. The present results show that the Γ‐subunit mRNA levels of F0F1‐ATPase are up‐regulated during biological stress conditions and elicitor treatments in potato and correlate with the increase of respiration rate and metabolic activity of mitochondria observed during infection processes in plants.