Exogenous spermidine is enhancing tomato tolerance to salinity-alkalinity stress by regulating chloroplast antioxidant system and chlorophyll metabolism.
Exogenous spermidine is enhancing tomato tolerance to salinity-alkalinity stress by regulating chloroplast antioxidant system and chlorophyll metabolism.
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DOI：
10.1186/s12870-015-0699-7
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发表时间：
2015-12-29
影响因子：
5.3
通讯作者：
Hu X
中科院分区：
文献类型：
--
作者：
Li J;Hu L;Zhang L;Pan X;Hu X
已知盐碱胁迫对植物的多种过程产生不利影响，从而抑制生长并降低作物产量。多胺保护植物免受各种环境胁迫。然而，外源亚精胺是否通过影响叶绿体抗氧化酶和叶绿素代谢来提高番茄幼苗的耐性尚不清楚。在这项研究中，我们研究了外源亚精胺对盐碱胁迫番茄幼苗叶绿素合成和降解途径中间产物和相关酶活性，以及叶绿体超微结构，基因表达和抗氧化剂的影响。盐碱胁迫破坏叶绿素代谢，阻碍尿卟啉原III转化为原卟啉IX。这些效应在中杂9号的幼苗中比在金鹏超冠的幼苗中更为明显。在盐碱胁迫下，外源亚精胺缓解了胁迫4d后两品种幼苗叶绿素总量和叶绿素a、B含量的下降。随着胁迫时间的延长，外源亚精胺降低了δ-氨基乙酰丙酸、胆色素原和尿卟啉原III的积累，增加了原卟啉IX、镁原卟啉IX和原叶绿素的含量，表明亚精胺促进了尿卟啉原III向原卟啉IX的转化。品种金鹏炒冠比品种中杂9号的效应发生早。外源亚精胺也缓解了胁迫诱导的丙二醛含量，超氧自由基的产生速率，叶绿素酶活性，叶绿素酶基因的表达和抗氧化酶，抗氧化剂的活性，和胆色素原脱氨酶基因的表达和胁迫诱导的减少的增加。此外，外源亚精胺还能稳定胁迫番茄幼苗叶绿体的超微结构。番茄品种表现出不同的能力，以应对盐碱胁迫。外源亚精胺可以有效地保护番茄幼苗免受盐碱胁迫引起的损伤，这可能是通过维持叶绿体结构完整性和减轻盐碱诱导的氧化损伤，最有可能是通过调节叶绿素代谢以及叶绿体中的酶和非酶抗氧化系统来实现的。外源亚精胺还在转录水平上发挥积极作用，如叶绿素酶基因的表达下调和胆色素原脱氨酶基因的表达上调。
Salinity–alkalinity stress is known to adversely affect a variety of processes in plants, thus inhibiting growth and decreasing crop yield. Polyamines protect plants against a variety of environmental stresses. However, whether exogenous spermidine increases the tolerance of tomato seedlings via effects on chloroplast antioxidant enzymes and chlorophyll metabolism is unknown. In this study, we examined the effect of exogenous spermidine on chlorophyll synthesis and degradation pathway intermediates and related enzyme activities, as well as chloroplast ultrastructure, gene expression, and antioxidants in salinity–alkalinity–stressed tomato seedlings. Salinity–alkalinity stress disrupted chlorophyll metabolism and hindered uroorphyrinogen III conversion to protoporphyrin IX. These effects were more pronounced in seedlings of cultivar Zhongza No. 9 than cultivar Jinpengchaoguan. Under salinity–alkalinity stress, exogenous spermidine alleviated decreases in the contents of total chlorophyll and chlorophyll a and b in seedlings of both cultivars following 4 days of stress. With extended stress, exogenous spermidine reduced the accumulation of δ–aminolevulinic acid, porphobilinogen, and uroorphyrinogen III and increased the levels of protoporphyrin IX, Mg–protoporphyrin IX, and protochlorophyllide, suggesting that spermidine promotes the conversion of uroorphyrinogen III to protoporphyrin IX. The effect occurred earlier in cultivar Jinpengchaoguan than in cultivar Zhongza No. 9. Exogenous spermidine also alleviated the stress–induced increases in malondialdehyde content, superoxide radical generation rate, chlorophyllase activity, and expression of the chlorophyllase gene and the stress–induced decreases in the activities of antioxidant enzymes, antioxidants, and expression of the porphobilinogen deaminase gene. In addition, exogenous spermidine stabilized the chloroplast ultrastructure in stressed tomato seedlings. The tomato cultivars examined exhibited different capacities for responding to salinity–alkalinity stress. Exogenous spermidine triggers effective protection against damage induced by salinity–alkalinity stress in tomato seedlings, probably by maintaining chloroplast structural integrity and alleviating salinity–alkalinity–induced oxidative damage, most likely through regulation of chlorophyll metabolism and the enzymatic and non–enzymatic antioxidant systems in chloroplast. Exogenous spermidine also exerts positive effects at the transcription level, such as down–regulation of the expression of the chlorophyllase gene and up–regulation of the expression of the porphobilinogen deaminase gene.