Effects of calcium on proline content and the relevant parameters were investigated in salt-stressed wheat seedlings. The results showed that proline content exhibited minor enhance under low salinity and significant increase under high salinity. Water-soluble carbohydrates and △' - pyrroline -5 - carboxylate reductase (P5CR) activity showed the same changing trend as proline. △' - Pyrroline -5 -carboxylate synthetase (P5CS) activity expressed insignificant changes under salinity. Proline dehydrogenase (PDH) only showed obvious increase under high salinity. Under salt stress K~+ content was obviously reduced, while Na~+ showed significant increase. After Ca~(2+) was applied, proline did not show obvious changes at low salinity, but showed significant decrease at high salinity, and their con?tents changed according to water-soluble carbohydrates content and P5CR activity. Ca~(2+) did not show obvious effect on P5CS activity and significantly increased PDH activity under high salinity. Ca~(2+) obviously decreased Na~+ content, increased K~+ content and the ratio of K~+/Na~+ in salt-stressed wheat seedlings. These results suggested that proline significantly accumulated only at high salinity, and Ca~(2+) could deduce obvious decrease in proline content in high salinity-stressed wheat plants. This effects might be related to the obvious decrease in P5CR activity and significant increase in PDH activity and the ratio of K~+ /Na~+.%研究了Ca~(2+)对盐胁迫小麦幼苗脯氨酸含量及相关酶活性的影响.结果表明,脯氨酸含量在低盐胁迫下增加不明显.高盐胁迫下显著增加;可溶性糖含量及吡咯琳-5-羧酸还原酶(P5CR)活性与其变化趋势一致; 吡咯琳-5-羧酸合成酶(P5CS)活性在盐胁迫下变化不明显;脯氨酸脱氢酶(PDH)活性在高盐胁迫下显著增加;盐胁迫下K~+含量显著降低,Na~+含量明显增加.加入Ca~(2+)后,脯氧酸含量在低盐胁迫下变化不明显,高盐胁迫下显著降低,与可溶性糖含量和P5CR活性变化一致;Ca~(2+)对P5CS活性无明显影响,而使高盐胁迫下PDH活性显著增加;Ca~(2+)明显降低了盐胁迫下Na~+含量,提高了K~+含量及K~+/Na~+.这说明脯氨酸仅在高盐胁迫下显著积累,Ca~(2+)明显降低了高盐胁迫下的脯氨酸含量,这一效应主要与P5CR活性降低、PDH活性及K~+/Na~+增加有关.
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