plays a role in ..., plays a key role in ..., plays a critical role in ...
Effective writers avoid overused expressions because such expressions are stale by definition, and stale writing indicates stale thinking.
Effective writers also avoid unintentionally repeating expressions, whether or not the expression are stale, for two reasons. First, like any other word pattern, repetition suggests meaning and the meaning of repetition is usually emphasis. In other words, effective writers repeat to emphasize. Second, unintended repetition makes the reader think that he is reading the same stuff again. The reader wonders whether she has lost her place, whether she hasn't accidentally started to read a paragraph she has already finished. Attentive readers soon recognize that they are dealing with a careless writer. Careless writing indicates careless thinking.
Unless you want your thinking to seem stale and careless, do not use stale expressions and do not unintentionally repeat expressions.
One of the most overused and unintentionally repeated expressions in scientific writing is "plays a role in." As an instructor in scientific writing, I frequently graded papers containing the phrase "plays a role in." And the phrase usually appeared not just once but many times in a 10-page paper.
One of the reasons I retired from the University of California at Davis was so that I would never again have to read the phrase "plays a role in." But my pension is too small to pay all the bills and so I started a technical editing business. In that business I learned that science students grow up to be professors who write papers in which a prominent concept is that X plays a role in Y. But X is often very important. Most often, X plays a critical role in Y.
I assume that "plays a role in" is a metaphor from the theater. Actors have roles in plays, i.e., actors play roles. But the metaphor is dead in that no one thinks of the theater when they hear or read "plays a role in." If it were not used so often, the expression could be effective. It reasonably indicates some undefined involvement of X in Y. But the expression is overused and should therefore be avoided.
Avoiding "plays a role in" can be difficult. One solution is to be more precise. For example, instead of saying that "rain plays a role in ascospore release," say that "rain increases ascospore release." Instead of saying that "enzyme X plays a role in gene silencing," say that "enzyme X silences genes by replacing hydroxyl groups with methyl groups." Such fixes are not available, however, when we are still ignorant about how X affects Y. In that case, we need to find alternative expressions for "plays a role in." Here are some alternatives:
In these examples, let X = potassium and Y = maintaining membrane integrity.
X functions in Y.
X contributes to Y.
X is involved in Y.
X is essential for Y.
As always, listen to your words and the ideas. If these alternatives seem inferior to "plays a role in," then use "plays a role in." But do not use it repeatedly. Also read about Prefabricated expressions and Cliches.