DJ fears the threat by board protest group the Sons of Struth to boycott season tickets and club merchandise could be disastrous for the club.
But he has warned the club's under-fire board to ignore the warning at their peril. He said: "I don't think the board can take this threat lightly. The fans have saved the club from extinction. The board has said that they will listen to what the fans want. If they don't listen to what the fans want on the 19th at the AGM this could happen.
"If enough Rangers fans think this way then they can hurt the club.
"The loss of income from season tickets and from merchandise sales could be serious for Rangers at a time when the financial situation of the club is a concern.
"I have said all along that I think the two groups, the board and the nominees, have to lock themselves in a room and try to reach a compromise agreement."
SoS, who are planning another major protest at the SPFL League One game with Ayr tomorrow, have emailed all of the major investors in the Glasgow giants.
They say fans will refuse to buy season tickets and official merchandise if the current board survives the AGM.
Former Rangers chairman Malcolm Murray, who is seeking election to the board along with Scott Murdoch, Paul Murray and Alex Wilson, this week warned he fears for the Ibrox club if the current directors win the vote at the AGM.
Johnstone would like to see both groups settle their differences and work together to return the Light Blues to the forefront of the Scottish game.
Johnstone added: "What is important in all of this is not the individual personalities, it is Rangers Football Club as a whole. Nothing is more important than the club.
"If somebody can do a good job for the club on the board, if they can bring in investment and help in its revival in some way, then I think they have to be considered.
"Somebody has to say: 'This individual has got a bit of quality, let's get them in and use their particular expertise to get the club moving forward on and off the park'. That has to happen.
"Dave King tried to get the two sides together. I think he is hoping that something like that can happen either before or after the AGM. Then he can get involved."