Kuang Qi, Zhang Sheng, Wu Pingzhi, Chen Yaping, Li Meiru, Jiang Huawu, Wu Guojiang
Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.
Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.
PLoS One. 2017 Aug 17;12(8):e0182700. doi: 10.1371/journal.pone.0182700. eCollection 2017.
Jatropha curcas L. is an important biofuel plant with excellent tolerance of barren environments. However, studies on the regulatory mechanisms that operate in this plant in response to nitrogen (N) shortage are scarce. In this study, genome-wide transcriptional profiles of the roots and leaves of 8-week old physic nut seedlings were analyzed after 2 and 16 days of N starvation. Enrichment results showed that genes associated with N metabolism, processing and regulation of RNA, and transport predominated among those showing alterations in expression. Genes encoding transporter families underwent major changes in expression in both roots and leaves; in particular, those with roles in ammonia, amino acid and peptide transport were generally up-regulated after long-term starvation, while AQUAPORIN genes, whose products function in osmoregulation, were down-regulated. We also found that ASPARA-GINASE B1 and SARCOSINE OXIDASE genes were up-regulated in roots and leaves after 2 and 16 d N starvation. Genes associated with ubiquitination-mediated protein degradation were significantly up-regulated. In addition, genes in the JA biosynthesis pathway were strongly activated while expression of those in GA signaling was inhibited in leaves. We showed that four major classes of genes, those with roles in N uptake, N reutilization, C/N ratio balance, and cell structure and synthesis, were particularly influenced by long-term N limitation. Our discoveries may offer clues to the molecular mechanisms that regulate N reallocation and reutilization so as to maintain or increase plant performance even under adverse environmental conditions.
麻疯树是一种重要的生物燃料植物，对贫瘠环境具有极强的耐受性。然而，关于该植物响应氮（N）短缺的调控机制的研究却很少。在本研究中，对8周龄麻疯树幼苗在氮饥饿2天和16天后的根和叶进行了全基因组转录谱分析。富集结果表明，与氮代谢、RNA加工和调控以及转运相关的基因在表达发生变化的基因中占主导地位。编码转运蛋白家族的基因在根和叶中的表达均发生了重大变化；特别是，那些在氨、氨基酸和肽转运中起作用的基因在长期饥饿后通常会上调，而其产物在渗透调节中起作用的水通道蛋白基因则下调。我们还发现，在氮饥饿2天和16天后，根和叶中的天冬酰胺酶B1和肌氨酸氧化酶基因上调。与泛素化介导的蛋白质降解相关的基因显著上调。此外，茉莉酸生物合成途径中的基因在叶中被强烈激活，而赤霉素信号通路中的基因表达则受到抑制。我们表明，四大类基因，即那些在氮吸收、氮再利用、碳/氮比平衡以及细胞结构和合成中起作用的基因，特别受到长期氮限制的影响。我们的发现可能为调控氮重新分配和再利用的分子机制提供线索，以便即使在不利的环境条件下也能维持或提高植物性能。
