Comparative Transcriptomic Studies on a Cadmium Hyperaccumulator Viola baoshanensis and Its Non-Tolerant Counterpart V. inconspicua
Comparative Transcriptomic Studies on a Cadmium Hyperaccumulator Viola baoshanensis and Its Non-Tolerant Counterpart V. inconspicua
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DOI：
10.3390/ijms20081906
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发表时间：
2019-04
影响因子：
5.6
通讯作者：
Shu;Zhang;Liu;Bian;Liang;Lin;Li;Shi;Liao
中科院分区：
文献类型：
--
作者：
Shu;Zhang;Liu;Bian;Liang;Lin;Li;Shi;Liao
许多生长在矿区的堇菜属植物表现出高水平的镉（Cd）耐性和积累，因此是比较研究Cd超积累分子机制的理想生物。然而，在堇菜科植物的超积累的转录组学研究很少。宝山堇菜是我国金属富集区的一种镉超富集植物，而其近缘种不显堇菜是一种非金属富集植物。在这里，通过转录组测序进行比较研究，以调查的关键途径，可能是负责这两个堇菜属物种之间的镉耐受性的差异水平。结果表明，在Cd胁迫下，宝山钒的泛素蛋白体系统（UPS）基因表达水平和激活程度明显提高，说明宝山钒对Cd胁迫的抗性可能与其对错误折叠蛋白的降解有关。许多与蔗糖代谢相关的基因，特别是那些参与胼胝质和海藻糖生物合成的基因，是两种堇菜之间表达差异最大的基因之一，这表明蔗糖代谢不仅在细胞壁修饰中起着至关重要的作用，通过碳供应，而且在抗氧化系统中作为信号分子或抗氧化剂。通过比较已知的几种转运蛋白的转录模式发现，在Cd胁迫下，宝山葡萄的几种液泡膜转运蛋白表达上调，表明Cd在液泡中的区室化作用更强。综上所述，我们的研究结果为宝山葡萄对Cd的超耐性提供了有价值的见解，相应的分子机制将有助于未来植物修复的基因工程。
Many Viola plants growing in mining areas exhibit high levels of cadmium (Cd) tolerance and accumulation, and thus are ideal organisms for comparative studies on molecular mechanisms of Cd hyperaccumulation. However, transcriptomic studies of hyperaccumulative plants in Violaceae are rare. Viola baoshanensis is an amazing Cd hyperaccumulator in metalliferous areas of China, whereas its relative V. inconspicua is a non-tolerant accumulator that resides at non-metalliferous sites. Here, comparative studies by transcriptome sequencing were performed to investigate the key pathways that are potentially responsible for the differential levels of Cd tolerance between these two Viola species. A cascade of genes involved in the ubiquitin proteosome system (UPS) pathway were observed to have constitutively higher transcription levels and more activation in response to Cd exposure in V. baoshanensis, implying that the enhanced degradation of misfolded proteins may lead to high resistance against Cd in this hyperaccumulator. Many genes related to sucrose metabolism, especially those involved in callose and trehalose biosynthesis, are among the most differentially expressed genes between the two Viola species, suggesting a crucial role of sucrose metabolism not only in cell wall modification through carbon supply but also in the antioxidant system as signaling molecules or antioxidants. A comparison among transcriptional patterns of some known transporters revealed that several tonoplast transporters are up-regulated in V. baoshanensis under Cd stress, suggesting more efficient compartmentalization of Cd in the vacuoles. Taken together, our findings provide valuable insight into Cd hypertolerance in V. baoshanensis, and the corresponding molecular mechanisms will be useful for future genetic engineering in phytoremediation.