College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China.
Faculty of Horticultural Science and Technology, Suzhou Polytechnic Institute of Agriculture, Suzhou, 215008, China.
BMC Plant Biol. 2023 Oct 18;23(1):499. doi: 10.1186/s12870-023-04514-2.
Fruit expansion stage is crucial to fruit yield and quality formation, and auxin plays a significant role by mediating multi-hormone signals during fruit expansion. However, till now, it is still unclear of the molecular regulatory network during auxin-mediated peach fruit expansion.
Here, exogenous NAA application markedly increased IAA content and drastically decreased ABA content at the fruit expansion stage. Correspondingly, NAA mainly induced the auxin biosynthesis gene (1 PpYUCCA) and early auxin-responsive genes (7PpIAA, 3 PpGH3, and 14 PpSAUR); while NAA down-regulated ABA biosynthesis genes (2 PpNCED, 1 PpABA3, and 1 PpAAO3). In addition, many DEGs involved in other plant hormone biosynthesis and signal transduction were significantly enriched after NAA treatment, including 7 JA, 7 CTK, 6 ETH, and 3 GA. Furthermore, we also found that NAA treatment down-regulated most of genes involved in the growth and development of peach fruit, including the cell wall metabolism-related genes (PpEG), sucrose metabolism-related genes (PpSPS), phenylalanine metabolism-related genes (PpPAL, Pp4CL, and PpHCT), and transcription factors (PpNAC, PpMADS-box, PpDof, PpSBP, and PpHB).
Overall, NAA treatment at the fruit expansion stage could inhibit some metabolism processes involved in the related genes in the growth and development of peach fruit by regulating multiple-hormone signaling networks. These results help reveal the short-term regulatory mechanism of auxin at the fruit expansion stage and provide new insights into the multi-hormone cascade regulatory network of fruit growth and development.
果实膨大期对果实产量和品质形成至关重要，生长素通过介导果实膨大过程中的多种激素信号发挥重要作用。然而，到目前为止，生长素介导桃果实膨大过程中的分子调控网络仍不清楚。
外源 NAA 处理在果实膨大期显著增加了 IAA 含量，大幅降低了 ABA 含量。相应地，NAA 主要诱导生长素生物合成基因（1 PpYUCCA）和早期生长素响应基因（7PpIAA、3 PpGH3 和 14 PpSAUR）；而 NAA 下调了 ABA 生物合成基因（2 PpNCED、1 PpABA3 和 1 PpAAO3）。此外，NAA 处理后，许多参与其他植物激素生物合成和信号转导的差异表达基因（DEGs）显著富集，包括 7 个 JA、7 个 CTK、6 个 ETH 和 3 个 GA。此外，我们还发现 NAA 处理下调了与桃果实生长发育相关的大多数基因，包括细胞壁代谢相关基因（PpEG）、蔗糖代谢相关基因（PpSPS）、苯丙氨酸代谢相关基因（PpPAL、Pp4CL 和 PpHCT）和转录因子（PpNAC、PpMADS-box、PpDof、PpSBP 和 PpHB）。
总之，果实膨大期 NAA 处理通过调节多种激素信号网络，抑制与桃果实生长发育相关基因的相关代谢过程。这些结果有助于揭示生长素在果实膨大期的短期调控机制，并为果实生长发育的多激素级联调控网络提供新的见解。
