Summary A majority of A rdisia species harbour B urkholderia sp. bacteria within specialized leaf nodules. The bacteria are transmitted hereditarily and have not yet been cultured outside of their host. Because the plants cannot develop beyond the seedling stage without their symbionts, the symbiosis is considered obligatory. We sequenced for the first time the genome of C andidatus B urkholderia crenata ( C a. B . crenata), t...