An experiment was carried out to increase salt tolerance of wheat plants by seed pre-soaking in GA3, and the relative value of proline is low in GA- treated plants, in comparison to untreated ones.
Dolatabadion et al. (2008) revealed that salt stress increased proline content, and application of vitamins scavenged ROS and prevented the biosynthesis of extra proline in canola plant, So I think the GA3 may behave the same effect as vitamins. Also the reduction of proline may be on the expence of its incorporation int protein
I know well that salinity increase the absolute value of proline . Furhermore, the exogenous application of GA3 increase wheat tolerance by increasing the ratio of proline to total amino acids not through the absolute value of proline.
Proline is a result of protein anabolism during salinity stress, As a poly N amino acid, It is used to catch amino group released during conversion of amino acid deamination to produce organic acids as an early step to obtain energy from plant proteins and lack of photo-assimilates as a result of salinity stress.
Proline induces tolerance, but not the thumb rule , depends on species. there is lot of literature indicating this.. the same has been tested through transgenic approach as well. If tolerance is exhibited in your case try to explaine with some more biochemicalaspects intricately involved in the process.
Proline accumulation under salt stress is obvious. The lower values of proline with application of GA is due to increased growth and photosynthetic activity of plants that dilutes the effects of salinity stress. Although hormones are known to induce osmolytes biosynthesis, the lower values in GA-treated plants are due to lowering of salinity stress and dilution factor.