Mechanism of Cu- and Cd-Induced Proline Hyperaccumulation in Triticum aestivum (Wheat)
Mechanism of Cu- and Cd-Induced Proline Hyperaccumulation in Triticum aestivum (Wheat)
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DOI：
10.1007/s00344-013-9343-7
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发表时间：
2013-06
影响因子：
4.8
通讯作者：
Bhumi Nath;Tripathi bullet;Vijeta Singh;bullet Bunichi;Ezaki bullet;V. Sharma;bullet J P Gaur
中科院分区：
文献类型：
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作者：
Bhumi Nath;Tripathi bullet;Vijeta Singh;bullet Bunichi;Ezaki bullet;V. Sharma;bullet J P Gaur
脯氨酸过度积累是植物界常见的一种现象，被认为是植物应对各种逆境的一种适应性策略。本研究探讨了过量铜、镉胁迫下普通小麦体内脯氨酸积累的机制。在试验金属处理的植物中，细胞内的Pro水平显著增加。铜和镉促进的Pro积累与处理植株的生长呈负相关，表明植物将其资源转移到诱导生存策略上，而不是促进生长发育。金属处理植株体内的吡咯烷-5-羧酸合成酶(P5CS)和吡咯烷-5-羧酸还原酶(P5CR)活性在处理后即刻升高，并一直保持在较高水平，而鸟氨酸氨基转移酶(OAT)活性低于P5CS和P5CR酶。在金属暴露的早期(最长达12h)，组织中的脯氨酸脱氢酶(PDH)活性急剧下降，但此后一直保持不变，直到实验结束。对P5CS、OAT和PDH转录本的表达分析也支持上述发现，并表明这些基因的组织特异性表达。基于这些结果，通过涉及P5CS和P5CR酶的谷氨酸途径增加的Pro合成是导致Pro过度积累的主要原因，随后是Pro分解代谢减少的主要原因。
Proline hyperaccumulation, a frequently reported phenomenon in the plant kingdom, is considered an adaptive strategy of plants to cope with a variety of stresses. The present study demonstrated the mechanism of proline hyperaccumulation inTriticum aestivumexposed to excess Cu and Cd. The intracellular level of proline was increased significantly in the plants treated with test metals. Enhanced proline accumulation due to Cu and Cd was negatively correlated with the growth of the treated plants, indicating that plants divert their resources toward induction of survival strategies rather than improving growth and development. The activities of pyrroline-5-carboxylate synthetase (P5CS) and pyrroline-5-carboxylate reductase (P5CR) were increased immediately after metal treatment and remained higher through the end of the experiment, whereas ornithine amino transferase (OAT) activity of the treated plants was lower than P5CS and P5CR enzymes. The activity of proline dehydrogenase (PDH) was decreased sharply in the early phase of metal exposure (up to 12 h) but remained unchanged thereafter until the end of the experiment. Expression analysis of the transcripts ofP5CS,OAT, andPDHalso supports the above findings and indicates the tissue-specific expression of these genes. Based on these results, increased proline synthesis through the glutamate pathway involving the P5CS and P5CR enzymes is a major contributor to proline hyperaccumulation followed by decreased catabolism of proline.