Final answer:
The GAPDH gene has a central role in glycolysis and also plays a significant part in plant stress responses, specifically in salt stress tolerance, by affecting ATP production and plant growth.
Step-by-step explanation:
The function of the GAPDH gene is principally involved in glycolysis, where it catalyzes the conversion of glyceraldehyde 3-phosphate to D-glycerate 1,3-bisphosphate. However, beyond its metabolic role, the GAPDH gene also appears to be involved in other cellular processes such as stress responses. In soybean, GAPDH has been identified as down-regulated at both the mRNA and protein levels in response to NaCl treatment, implying a role in salt stress tolerance. This down-regulation is associated with a reduction in ATP production and subsequent decrease in plant growth under salt stress conditions. Therefore, GAPDH can be an important target for genetic modification aiming to improve salt tolerance in plants.