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Abstract

The H+-ATPase HA1 of Medicago truncatulais essential for phosphate transport and plant growth during

A key feature of arbuscular mycorrhizal symbiosis is improved phosphorus nutrition of the host plant via the mycorrhizal pathway,i.e., the fungal uptake of Pi from the soil and its release from arbuscules within root cells. Efficient transport of Pi from the fungus to plant cells is thought to require a proton gradient across the periarbuscular membrane (PAM) that separates fungal arbuscules from the host cell cytoplasm. Previous studies showed that the H+-ATPase gene HA1 is expressed specifically in arbusculecontaining root cells of Medicago truncatula. We isolated a ha1-2 mutant of M. truncatula recapitulated this phenotype, resulting in small and truncated arbuscules. Unlike the wild type, the ha1-2 mutant failed to show a positive growth response to mycorrhizal colonization under Pi-limiting conditions. Uptake experiments confirmed that ha1-2
mutants are unable to take up phosphate via the mycorrhizal pathway. Increased pH in the apoplast of abnormal arbusculecontaining cells of the ha1-2 mutant compared with the wild type suggests that HA1 is crucial fo



Krajinski, F.; Courty, P.-E.; Sieh, D.; Franken, P.; Zhang, H.; Bucher, M.; Gerlach, N.; Kryvoruchko, I.; Zoeller, D.; Udvardi, M.; Hause, B. 2014. The H+-ATPase HA1 of Medicago truncatulais essential for phosphate transport and plant growth during arbuscular mycorrhizal symbiosis. Plant Cell 26, 1808-1817.