Orochimaru, in his quest to harvest the Shodai's abilities, injected his DNA into 60 test subjects, and out of the 60 only Tenzo survived. This gave Tenzo the Wood Release abilities. However, he is not as masterful as Hashirama.
A possibly unrelated technique, but unique to the First and Tenzou, is the Hokage Shiki • Jijun Jutsu • Kakuan Nitten Suishu. This technique produces a seal "sit" (座) on the user's hand that can suppress a tailed beast's influence over its host. This is done by producing wooden dragons from the ground that attach to the host and force the tailed beast's chakra to recede. The Shodai Hokage's Necklace aids in this technique's execution, because of the Shodai's chakra inside it.