Effect of water stress on proline catabolism in tobacco leaves

Proline-¹⁴C] infiltrated into leaf disks of tobacco (Nicotiana tabacum cv BY-4) in the dark was converted to glutamic acid and then metabolized through the TCA cycle. A smaller amount of proline-¹⁴C] was metabolized when the leaf disks were wilted than when turgid. During a 6 hr period following rehydration, disks converted a larger amount of proline-¹⁴C] to oxidized products than when wilted, although the proline content of rehydrated disks had not declined. These results indicate that proline oxidation is inhibited by water stress.