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为探讨裸燕麦对盐碱混合胁迫的脯氨酸(Pro)和多胺(PAs)响应机制,采用温室砂培试验,研究了低(25 mmol·L-1)、高(75 mmol·L~(-1))浓度盐碱混合胁迫0、1、3、5和7 d幼苗叶片Pro和PAs含量及相关代谢酶活性的变化。结果表明:与对照相比,盐碱混合胁迫在整个胁迫期间提高了裸燕麦叶片Pro含量,高浓度胁迫提高的幅度大于低浓度胁迫;低浓度胁迫下吡咯啉-5-羧酸合成酶(P5CS)活性提高,而鸟氨酸-δ-氨基转移酶(δ-OAT)和脯氨酸脱氢酶(Pro DH)活性受抑;高浓度胁迫下δ-OAT活性提高,而P5CS和Pro DH活性下降,说明低浓度胁迫下Pro合成以谷氨酸途径为主,高浓度胁迫下以鸟氨酸途径为主;低、高浓度盐碱混合胁迫下,游离态腐胺(Put)、亚精胺(Spd)和精胺(Spm)及结合态Spd和束缚态Spd、Spm含量提高,结合态Put、Spm和束缚态Put含量在胁迫1~5 d时提高,胁迫7 d时下降,且高浓度胁迫的变幅大于低浓度胁迫;Put/PAs和(c PAs+b PAs)/f PAs在胁迫1~3 d时提高,胁迫5~7 d时下降或变化不明显,(Spd+Spm)/Put的变化却相反;整个胁迫期间低浓度胁迫保持了较低的Put/PAs和较高的(Spd+Spm)/Put,(c PAs+b PAs)/f PAs除胁迫1 d时低浓度胁迫低于高浓度胁迫外,其余胁迫时间两浓度处理间差异不显著;精氨酸脱羧酶(ADC)和鸟氨酸脱羧酶(ODC)活性在低、高浓度盐碱混合胁迫期间提高,二胺氧化酶(DAO)活性在胁迫1~3 d下降或变化不大,胁迫5~7 d时升高,多胺氧化酶(PAO)活性的变化与DAO相反,且高浓度胁迫下ADC、ODC、DAO和PAO的变幅大于低浓度胁迫。说明盐碱混合胁迫初期(1~3 d)游离态PAs(f PAs)向结合态和束缚态PAs(cPAs+bPAs)转化增强,低浓度胁迫后期(5~7 d)Put向Spd和Spm转化的能力强于高浓度胁迫,但高浓度胁迫在整个胁迫期间PAs合成和分解的速率更高。
In order to investigate the mechanism of the response of proline (Pro) and polyamines (PAs) to salt and alkali in naked oats, the effects of low (25 mmol·L-1) and high (75 mmol·L- (-1)) Concentrations of Pro and PAs and the Activities of Related Metabolic Enzymes in Seedlings Leaves at 0, 1, 3, 5 and 7 D under Salt and Alkali Mixed Stress. The results showed that compared with the control, the mixed salt-alkali stress increased the content of Pro in naked oat leaves throughout the stress period, and the increase of high concentration stress was greater than that of low concentration stress. Under low concentration stress, pyrroline-5-carboxylic acid synthase (P5CS ) Activity, while the activity of ornithine-δ-aminotransferase (δ-OAT) and proline dehydrogenase (Pro DH) was inhibited. The δ-OAT activity increased under high concentration stress, while the activities of P5CS and Pro DH (P <0.05), indicating that glutamate pathway is the main pathway for the synthesis of Pro under low concentration stress and Ornithine pathway is the main pathway under high concentration stress. Under low and high concentration of salt and alkali mixed stress, the contents of free putrescine (Put), spermidine Spd and Spm and bound Spd and bound Spd and Spm increased, bound Put, Spm and bound Put increased at 1 ~ 5 d of stress, decreased at 7 d of stress, and high concentration of stress (Ps + b PAs) / f PAs increased from 1 to 3 d after stress, but decreased or changed little from 5 to 7 d after stress, while (Spd + Spm) / Put (Ps + bPAs) / f PAs maintained at a low level for a long time under low stress, and low (cPAs + bPAs) / f PAs maintained low In high The concentration of arginine decarboxylase (ADC) and ornithine decarboxylase (ODC) increased during the low and high concentrations of salt and alkali mixed stress while the activities of diamine oxidase DAO decreased or little changed from 1 to 3 d after stress, and increased from 5 to 7 d after stress. The changes of polyamine oxidase (PAO) activity were opposite to that of DAO, and ADC, ODC, DAO and PAO The amplitude is greater than the low concentration stress. The results showed that the conversion of free PAs (f PAs) and bound PAs (cPAs + bPAs) increased in the early stage of salt and alkali mixed stress (1 ~ 3 d) The ability of PAs to synthesize and decompose is higher than that of high concentration stress during the whole stress.