Fatty acid (FA) levels and profiles are vital for soybean oil quality, while cytokinins (CKs) and abscisic acid (ABA) are potent regulators of plant growth and development. Previous research suggested associations between FA biosynthesis and hormonal signalling networks; however, hormonal regulation of FA accumulation during soybean (Glycine max) seed maturation has never been measured. We analysed hormone and FA profiles obtained from HPLC-(ESI)-MS/MS and GC-FID screening during soybean seed maturation. A multilayered data processing approach, involving heat-maps, principal component analysis (PCA), correlation and multiregression models, suggested a strong relationship between hormone metabolism and FA/oil accumulation during seed maturation. Most strikingly, positive correlations were found between the levels of CK ribosides [transZeatin riboside (tZR), N6-isopentenyladenosine (iPR)] at the early stages of SM (R5-R6) and C18:0, C18:2 and oil content at the R8 stage. Moreover, multiple regression models revealed functional linkages between several CK derivatives and FA and oil content in mature seeds. To further test the significance of hormone regulation in FA metabolism, plants of two soybean accessions with contrasting hormone and FA profiles were sprayed with exogenous ABA and transZeatin (tZ) during the seed-filling period (R5-R6). Depending on the hormone type and concentration, these treatments distinctly modified biosynthesis of all tested FAs, except for C18:0. Most remarkably, tZ (50 nM) promoted production of C16:0, C18:1, C18:2, C18:3, and oil accumulation in maturing seeds. Overall, the results indicate impactful roles for ABA and CKs in FA accumulation during SM and represent a further step towards understanding FA biosynthesis, and potential improvements of soybean oil profiles.

中文翻译：

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植物激素动力学影响大豆种子成熟过程中脂肪酸和油脂的积累

脂肪酸 (FA) 水平和谱对大豆油质量至关重要，而细胞分裂素 (CKs) 和脱落酸 (ABA) 是植物生长和发育的有效调节剂。先前的研究表明 FA 生物合成与激素信号网络之间存在关联；然而，大豆过程中 FA 积累的激素调节（最大甘氨酸) 从未测量过种子成熟度。我们分析了在大豆种子成熟期间从 HPLC-(ESI)-MS/MS 和 GC-FID 筛选获得的激素和 FA 谱。涉及热图、主成分分析 (PCA)、相关性和多元回归模型的多层数据处理方法表明，种子成熟过程中激素代谢与 FA/油积累之间存在密切关系。最引人注目的是，在 CK 核苷水平之间发现了正相关[反式玉米素核苷（吨ZR),ñ6-异戊烯基腺苷（iPR）]在SM（R5-R6）的早期阶段和C18：0，C18：2和R8阶段的油含量。此外，多元回归模型揭示了几种 CK 衍生物与成熟种子中的 FA 和含油量之间的功能联系。为了进一步测试激素调节在 FA 代谢中的重要性，对两种具有对比激素和 FA 谱的大豆品种的植物喷洒外源 ABA 和反式玉米素（吨Z) 在种子灌浆期 (R5-R6)。根据激素类型和浓度，这些处理明显改变了所有测试 FAs 的生物合成，C18:0 除外。最引人注目的是，吨Z (50 nM) 促进 C16:0、C18:1、C18:2、C18:3 的产生和成熟种子中的油积累。总体而言，结果表明 ABA 和 CK 在 SM 期间 FA 积累中的重要作用，代表了进一步了解 FA 生物合成和大豆油特性的潜在改进。