外源脱落酸对干旱胁迫下云南山茶幼苗内源激素代谢的影响

Effects of Abscisic Acid Spray on Hormone Metabolism of Camellia reticulata Seedlings under Drought Stress

【目的】探究喷施外源脱落酸(abscisic acid,ABA)对干旱胁迫下两年生云南山茶紫袍(Camellia reticulata‘Zipao’)幼苗根和叶内源激素的影响。【方法】采用100 mg·L^(−1)脱落酸对云南山茶幼苗叶面喷施,并用PEG_6000模拟干旱法进行干旱胁迫,研究在干旱胁迫及复水处理下外源ABA对云南山茶根和叶的渗透调节物质和内源激素代谢组的影响。【结果】干旱及复水处理下渗透调节的关键部位是在叶。干旱胁迫下云南山茶幼苗根部促进ABA、赤霉素(gibberellins,GA)、细胞分裂素(cytokinins,CKs)含量,降低生长素(auxin,IAA)含量,而叶部促进ABA、茉莉酸(jasmonates,JA)、水杨酸(salicylic acid,SA)、IAA、CKs含量的积累。复水处理下云南山茶幼苗根部ABA、GA、CKs各激素水平逐渐下降,IAA含量逐渐上升,而叶部通过积累JA、SA、IAA、CKs含量进行调控。差异显著代谢物KEGG富集分析表明,根部代谢物显著富集在二萜生物合成通路中,叶部显著富集在植物激素信号转导途径和玉米素生物合成通路中。渗透调节物质与内源激素的相关性分析表明二者之间存在显著正相关。施用外源ABA在干旱胁迫下可分别提升云南山茶根部可溶性蛋白、可溶性糖、ABA、GA、CKs和叶部游离脯氨酸、ABA、JA的含量,进而提高耐旱力;在复水期可分别降低根部CKs和叶部JA的含量,促进根部和叶部IAA的合成,进而促进植株的恢复。【结论】云南山茶幼苗根和叶对干旱胁迫及复水处理的响应存在差异,施用外源ABA可提高云南山茶的耐旱力。

【Objective】Effects of ABA spray on endogenous hormones in Camellia reticulata seedlings under drought stress were studied.【Methods】An ABA solution in the concentration of 100 mg·L^(−1)was sprayed on the leaves of 2-year-old C.reticulata Zipao seedlings grown in potting soil under a simulated drought stress using PEG_6000.Osmoregulatory substances and hormone metabolome in the roots and leaves of the plants were measured under the treatment and subsequent rehydration.【Results】Osmotic regulation of the seedlings took place mainly in the leaves.Under drought stress,ABA,JA,SA,IAA,and CKs accumulated in the leaves,while ABA,GA,and CKs increased but IAA decreased in the roots.Upon rehydration,ABA,GA,and CKs in the roots gradually declined,while IAA rose,meanwhile,the leaves started regulating with the stored JA,SA,IAA,and CKs.The KEGG enrichment analysis showed that the diterpene biosynthesis pathway in the roots and the hormone signal transduction and zein biosynthesis pathways in the leaves were significantly enhanced.There was a significant correlation between the osmoregulatory substances and endogenous hormones.The ABA spray boosted the contents of soluble protein,soluble sugar,ABA,GA,and CKs in the roots as well as those of free proline,ABA,and JA in the leaves improving the drought tolerance of the plant.With replenished water,CKs in the roots and JA in the leaves were reduced to encourage IAA synthesis,which in turn,aided the recovery of plant functions.【Conclusion】The responses of the roots and leaves of C.reticulata seedlings to the imposed drought and the subsequent rehydration were different.Application of foliar ABA spray could improve the draught resistance of the plants.