Isle of Man-based businessman Davies has continued to bankroll the club throughout their Premier League era and having already sanctioned the purchases of Elmander and Muamba, he is intent on ensuring Bolton remain a top-flight force.
Gartside said: "If it wasn't for Eddie, we could even not be in existence that is how crucial it was when he joined the club 10 years ago.
"He has put more personal investment into Bolton than any other person in the history of the club, relative to the period he has supported us.
"Basically, he is a fan and the reason for him being involved is that he wants to have fun, he wants Bolton to survive and he doesn't want to lose his money - as long as we keep going with those three promises we expect him to keep supporting us for some time to come."
Gartside added: "Johan's arrival represents a record fee for the club and is Gary's sixth signing since January.
"We have had scouts at all the tournaments in the summer and we have had discussions with players and football clubs to rejig the squad and bring in players that Gary wants.
"We have a hit-list of players and positions but it is not a one-year task - it has to be done over a period.
"We don't have a huge chequebook but what we are doing is bringing in better quality than we have lost to improve the squad."