The enzyme is also ubiquitous in C3 plant tissues, although a precise non-photosynthetic C3 function(s) is yet to be validated, owing largely to its low abundance in most C3 organs.

The previous studies showed that the expression of chloroplast GS2 is mediated by light but cytosolic GS1 and GS in non photosynthetic tissues of higher plants are little influenced.

Aluminum stress was found to affect the photosynthesis of longan seedlings and reduce the photosynthetic efficiency. The non-stomas factors were observed to mainly hinder the photosynthesis.