不同树龄临泽小枣根系内源激素含量及代谢组学分析

Analysis of Endogenous Hormones and Metabolomics in Ziziphus jujuba ‘Linze’Root of Different Ages

摘要:

通过测定临泽小枣不同树龄(30 a、50 a、100 a、300 a)的水平根、单位根、细根不同根系类型内源激素含量，开展不同根系类型内源激素含量差异分析和代谢组学分析，探讨临泽小枣根蘖繁殖力与内源激素的关系，提出促进临泽小枣种群繁殖潜力的措施，为提高临泽小枣根蘖诱导率提供理论参考，从而为临泽小枣种群保护恢复提供科学依据。结果表明，在临泽小枣根系中共检测到21种植物内源激素，包含17种生长素、1种脱落酸、3种赤霉素，生长素L-色氨酸含量最高。不同树龄临泽小枣根系激素含量动态变化：ABA含量随树龄的增加基本呈降低趋势；IAA-Asp、Indole、TRP、IAAAla、IAA-Val均随树龄增大，呈先增大后减小趋势；GA3含量很小，随树龄增大而先减小后增大。代谢组学分析共筛选出9种差异代谢物，包含7种生长素和2种赤霉素，主要分布在氨基酸、酚酸和类黄酮等化合物中。KEGG通路主要富集在代谢途径、次生代谢物的生物合成、二萜生物合成、色氨酸代谢、氨酰生物合成、辅因子生物合成、2-氧羧酸代谢等生物途径上。由此推测，内源激素中促生长物质IAA的含量远远大于ABA含量是临泽小枣根蘖形成的内源影响因子。

Abstract:

The endogenous hormone contents in three root types(horizontal roots, unit lateral roots, and fine roots) of Ziziphus jujuba‘Linze’at four tree ages(30 a, 50 a, 100 a, and 300 a) were determined. Comparative analysis of endogenous hormone contents among different root types and metabolomic analysis were carried out, to explore the relationship between root sprouting reproductive capacity and endogenous hormones in Z. jujuba ‘Linze’. On this basis, measures to improve the population reproductive potential of Z. jujuba ‘Linze’ were proposed, aiming to provide a theoretical reference for increasing the induction rate of root sprouting, and a scientific basis for the protection and restoration of Z. jujuba ‘Linze’ populations. The results showed that, a total of 21 plant endogenous hormones were detected in the roots of Z. jujuba ‘Linze’, including 17 auxins, 1 abscisic acid (ABA), and 3 gibberellins(GAs), among which L-tryptophan(TRP, an auxin precursor) had the highest content. Dynamic changes of hormone contents in roots of Z. jujuba ‘Linze’ at different tree ages were observed: ABA content basically showed a decreasing trend with the increase of tree age; the contents of IAA-Asp, Indole, TRP, IAA-Ala, and IAA-Val all showed a trend of first increasing and then decreasing with the increase of tree age; GA3 content was extremely low, and a trend of first decreasing and then increasing with tree age was presented. A total of 9 differentially accumulated metabolites(DAMs) were screened out by metabolomic analysis, including 7 auxins and 2 gibberellins, which were mainly classified into amino acids, phenolic acids, and flavonoids. KEGG pathway enrichment analysis showed that these DAMs were mainly enriched in biological pathways including metabolic pathways, biosynthesis of secondary metabolites, diterpenoid biosynthesis, tryptophan metabolism, aminoacyl-tRNA biosynthesis, biosynthesis of cofactors, and 2-oxocarboxylic acid metabolism. It is concluded that the significantly higher content of the growth-promoting hormone indole-3-acetic acid(IAA) than ABA in endogenous hormones is the key endogenous factor regulating root sprouting formation in Z. jujuba‘Linze’.