Instituto de Ciencias Biológicas, Campus Talca, Universidad de Talca, Avda. Lircay s/, Talca, Chile.
Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Pozuelo de Alarcón, Spain.
Plant Physiol Biochem. 2019 Feb;135:215-223. doi: 10.1016/j.plaphy.2018.12.008. Epub 2018 Dec 15.
Plants respond to the loss of vertical growth re-orientating their affected organs. In trees, this phenomenon has received the scientific attention due to its importance for the forestry industry. Nowadays it is accepted that auxin distribution is involved in the modulation of the tilting response, but how this distribution is controlled is not fully clear. Auxin transporters that determine the spatio-temporal auxin distribution in radiate pine seedlings exposed to 45° of tilting were identified. Additionally, based on indications for an intimate plant hormone crosstalk in this process, IAA and JA contents were evaluated. The experiments revealed that expression of the auxin transporters was down-regulated in the upper half of the tilted stem, while being induced in the lower half. Moreover, transporter-coding genes were first induced at the apical zone of the stem. IAA was consistently redistributed toward the lower half, which is in accordance with the expression profile of the auxin transporters. In contrast, JA was mainly accumulated in the upper half of tilted stems. Finally, lignin content and monomeric composition were analyzed in both sides of stem and along the time course of tilting. As expected, lignin accumulation was higher at the lower half of stem at longer times of tilting. However, the most marked difference was the accumulation of the H-lignin monomer in the lower half, while the G-lignin unit was more dominant in the upper half. Here, we provide detailed insight in the distribution of IAA and JA, affecting the lignin composition during the tilting response in Pinus radiata seedlings.
植物会因失去纵向生长而重新定向受影响的器官。在树木中，由于其对林业产业的重要性，这一现象引起了科学界的关注。如今，人们普遍认为生长素的分布参与了倾斜反应的调节，但这种分布是如何控制的还不完全清楚。本研究鉴定了在 45°倾斜的辐射松幼苗中决定生长素时空分布的生长素转运体。此外，基于该过程中生长素和茉莉酸之间存在密切的植物激素相互作用的迹象，评估了 IAA 和 JA 的含量。实验表明，在倾斜茎的上半部分，生长素转运体的表达下调，而在下半部分被诱导。此外，转运体编码基因首先在上茎尖区被诱导。IAA 一直重新分配到下半部分，这与生长素转运体的表达模式一致。相反，JA 主要在倾斜茎的上半部分积累。最后，在茎的两侧和倾斜过程中分析了木质素含量和单体组成。不出所料，在倾斜时间较长时，木质素在茎的下半部分积累更多。然而，最显著的差异是 H-木质素单体在下半部分的积累，而 G-木质素单元在上半部分更为优势。在这里，我们提供了在 Pinus radiata 幼苗倾斜反应过程中 IAA 和 JA 分布的详细信息，影响木质素组成。
