盐胁迫下小麦苗叶片吡咯-5-羧酸还原酶活性和游离脯氨酸积累

受NaCl、KCl或MsCl_2胁迫的小麦幼苗,当外部溶液的渗透势由—160 kPa下降到—900 kPa时,叶片吡咯—5—羧酸还原酶(PSC)活性增高;渗透势由—900 kPa降低到—1500kPa,酶活性下降;胁迫 1d和 2d的幼苗,还原酶活性显著增加;3～6d酶活性无大变化。游离脯氨酸含量随溶液渗透势下降和培养时间的延长而提高。胁迫解除后酶活性和脯氨酸含量均降低。受NcCl胁迫义在ABA影响下的幼苗,P5C还原酶活性和脯氨酸含量高于仅受NaCl胁迫的幼苗。

Pyrroline-5-Carboxylate Reductase Activity and Free Proline Accumulation in Leaves of Triticum aestivum Seedlings Under Salt Stress

This paper reports the relationshipbetween pyrroline--5--carboxylate (P5C)reductase activity and free proline accu-mulation in leaves of Triticum aestirumseedlings grown in Hoagland nutrientsolution containing NaCl, KCl or Mg-Cl_2. The effect of exogenous ABA onP5C reductase activity and proline accu-mulation of seedling leaves under saltstress is also reported. The results showed that the freeproline content increased markedly witha lowering of osmotic potential of exter-nal solution or the prolongation of cul-ture time under low osmotic potential(Fig. 1). When the osmotic potential ofNaCl, KCl or MgCl_2 solution decreased,P5C reduction activity first increasedand reached a maximum at -900 kPa(Fig. 1). When seedlings were culturedin NaCl solution, reductase activity rosemarkedly on the 1st and 2nd days, andremained at a high level from the 3rd to6th days (Fig. 3). Seedlings culturedalternately in Hoagland solution aloneor Hoagland solution containing NaCl at--900 kPa showed that there was posi-tive relation between the P5C reductaseactivity and free proline accumulation. Under salt stress the P5C reductaseactivity and free proline content wereincreased by exogenous ABA. In NaClsolution with an osmotic potential of -900 kPa containing different concentra-tions of ABA, P5C reductase activityand proline content were highest at 10~(-3)mmol/L ABA. Therefore, the enhancement ofP5C reductase activity can be cause offree proline accumulation under saltstress.