不同发育时期核桃内果皮的差异代谢物分析

Analysis of different metabolites in the endocarp of walnut at different developmental stages

为探明核桃内果皮发育过程中代谢物的变化和木质化发育规律,以不同发育期的‘赞美’核桃内果皮为材料进行了代谢物测定,同时结合转录组信息,研究不同发育时期核桃内果皮中代谢物质的变化及相关基因的转录与表达。结果表明:不同发育期核桃内果皮中代谢物具有显著差异。通过高效液相色谱-质谱联用(UPLC-MS)对样品进行检测分析共鉴定出7 837个代谢物,对其进行筛选后,共得到2 633个差异代谢物,包括核苷酸及其衍生物、脂质、酚酸、氨基酸及其衍生物、生物碱、糖苷、有机酸、木脂素、黄酮类等,被注释到35个代谢通路中,其中玉米素生物合成、组氨酸代谢、核黄素代谢、硫胺素代谢、苯丙氨酸和酪氨酸及色氨酸生物合成通路最显著;硫代葡萄糖苷生物合成、嘌呤代谢、卟啉和叶绿素代谢和苯丙烷类生物合成通路富集到最多差异代谢物。花后45 d时,大部分的差异代谢物的含量较花后20 d时降低。转录组与代谢组联合分析发现,二者具有22个相同的代谢通路,包括玉米素生物合成通路等;激素代谢相关通路和苯丙烷生物合成相关通路中差异代谢物变化与酶编码基因的表达情况一致。核桃内果皮代谢物分析为揭示内果皮发育规律,提高其利用价值提供了理论依据。

In order to investigate the changes of metabolites and lignification during the development of walnut endocarp, the metabolites of walnut(‘Zanmei’) endocarp in different development stages were measured. At the same time, we combined the transcriptome information to study the changes of metabolites and expression of related genes in walnut endocarp at different development stages. The results showed that there were significant differences in the metabolites in walnut endocarp at different development stages. A total of 7837 metabolites were identified by high performance liquid chromatography-mass spectrometry(UPLC-MS). After screening, a total of 2633 differential metabolites were obtained, including nucleotides and derivatives, lipids, phenolic acids, amino acids and derivatives, alkaloids, glycosides, organic acids, lignans, flavonoids, etc. They were classified into 35 metabolic passways, among which, zeatin biosynthesis, histidine metabolism, riboflavin metabolism, thiamine metabolism, phenylalanine, tyrosine and tryptophan biosynthesis pathways were the most significant. Glucosinolates biosynthesis, purine metabolism, porphyrin and chlorophyll metabolism, and phenylpropanoid biosynthesis pathways were enriched with the most differentiated metabolites. At 45 days after anthesis, the contents of most of the differential metabolites were lower than those at 20 days after anthesis. Combined transcriptome and metabolome analysis showed that there were 22 similar metabolic pathways, including zeatin biosynthesis pathway and so on. The changes of differential metabolites in hormone metabolism and phenylpropanoid biosynthesis pathway were consistent with the expression of genes encoding the enzymes. The analysis of the metabolites in walnut endocarp provided a theoretical basis for revealing the development rule of endocarp and improving its utilization value.