Overexpression of Arabidopsis AtmiR393a gene alters the sensitivity to auxin in tomato

MicroRNA miR393 is highly conserved both in sequence and function in different plants by posttranscriptionally cutting auxin receptor genes. To examine if miR393 functions in tomato, a fragment of AtmiR393a gene was amplified from Arabidopsis and introduced into tomato with Agrobacterium-mediated transformation. Three transgenic lines with different expression levels of AtmiR393a gene were chosen to identify the function of miR393 in tomato. The results showed that three transgenic tomato lines produced smaller seeds, shorter roots in seedlings and less adventitious roots in hypocotyls than the non-transgenic control. In addition, transgenic tomatoes exhibited reduced phototropic growth habit relative to the control. Our findings indicated that AtmiR393a overexpression made the transgenic tomato hyposensitive to auxin signal, suggesting that miR393 may function in a conserved way by posttranscriptionally cleaving its target genes in tomato.