[erazeN]

This is partly incorrect. Not everyone of the Senju clan could use mokuton, only Hashirama. The second Hokage who was his brother(Tobirama Senju) was known for using suiton(water) techniques, and he was not able to use mokuton or to control the tailed beasts. Tsunade is his grandaughter but she is not able to use mokuton either.
His bloodline limit was unique to him(somewhat like Pain's rinnegan) which was probably the way he could control the beasts, and there has never been any other known person in Konoha able to use mokuton except Yamato. Which is like you said why Yamato can at some point control the kyuubi, in combination with the 1sts necklace.

But none of that is relevant. I merely was trying to compare the possibility of Akainu's df being the control of life plant in a similar way to the 1st Hokage(and Yamato)...