Abstract:
Adenylyl cyclases (ACs) catalyze the formation of adenosine3',5'-cyclic monophosphate (cAMP) from adenosine 5'-triphosphate (ATP). The Arabidopsis genome
contains two genes, At3g14460 (AC1) and At3g14470 (AC2) which have an aminoterminal
nucleotide binding domain and sequence homology to maize AC. Expression of
AC1 and AC2 complemented the E.coli cAMP mutant, cya suggesting that both proteins
produce functional cAMP in vivo. Gene expression studies using RT-PCR and promoter-
GUS staining showed that AC1 is expressed in root tips, inflorescence and anthers, while
AC2 is expressed in stem, roots, cauline leaves, senescent leaves, and inflorescences. TDNA insertion mutants of ac1 and ac2 showed a delay and a reduction in germination under salt stress. Conversely, overexpression of AC1 and AC2 conferred some protection against salt stress. Taken together, I infer that cAMP may have a role in salinity tolerance.
