College of Agronomy, Sichuan Agricultural University, Chengdu 611130, China.
Mianyang Academy of Agricultural Sciences, Mianyang 621023, China.
Int J Mol Sci. 2017 Oct 30;18(11):2280. doi: 10.3390/ijms18112280.
Sprouting regulation in potato tubers is important for improving commercial value and producing new plants. Camphor shows flexible inhibition of tuber sprouting and prolongs the storage period of potato, but its underlying mechanism remains unknown. The results of the present study suggest that camphor inhibition caused bud growth deformities and necrosis, but after moving to more ventilated conditions, new sprouts grew from the bud eye of the tuber. Subsequently, the sucrose and fructose contents as well as polyphenol oxidase (PPO) activity were assessed after camphor inhibition. Transcription and proteomics data from dormancy (D), sprouting (S), camphor inhibition (C), and recovery sprouting (R) samples showed changes in the expression levels of approximately 4000 transcripts, and 700 proteins showed different abundances. KEGG (Kyoto encyclopaedia of genes and genomes) pathway analysis of the transcription levels indicated that phytohormone synthesis and signal transduction play important roles in tuber sprouting. Camphor inhibited these processes, particularly for gibberellic acid, brassinosteroids, and ethylene, leading to dysregulation of physiological processes such as cutin, suberine and wax biosynthesis, fatty acid elongation, phenylpropanoid biosynthesis, and starch and sucrose metabolism, resulting in bud necrosis and prolonged storage periods. The KEGG pathway correlation between transcripts and proteins revealed that terpenoid backbone biosynthesis and plant-pathogen interaction pathways showed significant differences in D vs. S samples, but 13 pathways were remarkably different in the D vs. C groups, as camphor inhibition significantly increased both the transcription levels and protein abundance of pathogenesis-related protein PR-10a (or STH-2), the pathogenesis-related P2-like precursor protein, and the kirola-like protein as compared to sprouting. In recovery sprouting, these genes and proteins were decreased at both the transcriptional level and in protein abundance. It was important to find that the inhibitory effect of camphor on potato tuber sprout was reversible, revealing the action mechanism was similar to resistance to pathogen infection. The present study provides a theoretical basis for the application of camphor in prolonging seed potato storage.
块茎发芽调控对于提高商业价值和生产新植株非常重要。樟脑具有灵活抑制块茎发芽的作用，并能延长马铃薯的贮藏期，但作用机制尚不清楚。本研究结果表明，樟脑抑制导致芽生长畸形和坏死，但在转移到通风条件更好的环境后，新的芽从块茎的芽眼处长出。随后，评估了樟脑抑制后蔗糖和果糖含量以及多酚氧化酶（PPO）活性。休眠（D）、发芽（S）、樟脑抑制（C）和恢复发芽（R）样本的转录组和蛋白质组学数据显示，约有 4000 个转录本的表达水平发生变化，700 种蛋白质的丰度不同。转录水平的 KEGG（京都基因与基因组百科全书）途径分析表明，植物激素的合成和信号转导在块茎发芽中起着重要作用。樟脑抑制了这些过程，特别是赤霉素、油菜素内酯和乙烯，导致角质、亚角质和蜡生物合成、脂肪酸延伸、苯丙烷生物合成以及淀粉和蔗糖代谢等生理过程失调，导致芽坏死和延长贮藏期。转录本和蛋白质之间的 KEGG 途径相关性表明，萜烯骨架生物合成和植物-病原体相互作用途径在 D 与 S 样本之间存在显著差异，但在 D 与 C 组之间有 13 条途径差异显著，因为与发芽相比，樟脑抑制显著增加了病程相关蛋白 PR-10a（或 STH-2）、病程相关 P2 样前体蛋白和 kirola 样蛋白的转录水平和蛋白丰度。在恢复发芽中，这些基因和蛋白质在转录水平和蛋白丰度上都有所下降。重要的是发现樟脑对马铃薯块茎芽的抑制作用是可逆的，这表明其作用机制与对病原体感染的抗性相似。本研究为樟脑在延长种薯贮藏中的应用提供了理论依据。
