Molecular cloning and characterization of a potato cDNA encoding a stress regulated Aux/IAA protein

Aux/IAA genes are rapidly activated in response to auxin. These genes encode short-lived and nuclear-localized proteins. Here we report the isolation and expression analysis of an Aux/IAA cDNA from Solanum tuberosum L. tuberosum (cv Spunta), named StIAA. The StIAA cDNA clone was obtained by differential screening of a Fusarium solani f. sp. eumartii-infected potato tubers cDNA library. The StIAA cDNA contains a full-length open reading frame, and its deduced amino acid sequence displays high degree of conservation with Aux/IAA proteins isolated from other plant species. Northern blot analysis indicated that StIAA transcripts accumulate in potato tubers after fungal infection, as well as wounding. StIAA mRNA levels also significantly increased in potato leaves upon indole-3-acetic acid treatment. These results suggest that StIAA gene products may be involved in different physiological events in potato, including potato responses induced during fungal infection and wounding. The role of auxin and Aux/IAA proteins during plant defense response is discussed.