Table_1_Impact of Within-Tree Organ Distances on Floral Induction and Fruit Growth in Apple Tree: Implication of Carbohydrate and Gibberellin Organ Contents.xlsx

In plants, organs are inter-dependent for growth and development. Here, we aimed to investigate the distance at which interaction between organs operates and the relative contribution of within-tree variation in carbohydrate and hormonal contents on floral induction and fruit growth, in a fruit tree case study. Manipulations of leaf and fruit numbers were performed in two years on “Golden delicious” apple trees, at the shoot or branch scale or one side of Y-shape trees. For each treatment, floral induction proportion and mean fruit weight were recorded. Gibberellins content in shoot apical meristems, photosynthesis, and non-structural carbohydrate concentrations in organs were measured. Floral induction was promoted by leaf presence and fruit absence but was not associated with non-structural content in meristems. This suggests a combined action of promoting and inhibiting signals originating from leaves and fruit, and involving gibberellins. Nevertheless, these signals act at short distance only since leaf or fruit presence at long distances had no effect on floral induction. Conversely, fruit growth was affected by leaf presence even at long distances when sink demands were imbalanced within the tree, suggesting long distance transport of carbohydrates. We thus clarified the inter-dependence and distance effect among organs, therefore their degree of autonomy that appeared dependent on the process considered, floral induction or fruit growth.

植物各器官的生长与发育存在相互依存关系。本研究以果树为研究对象，旨在探究器官间相互作用的作用距离，以及树体内碳水化合物与激素含量的变异对成花诱导(floral induction)和果实生长的相对贡献。本研究于两年内针对金冠(Golden Delicious)苹果树，在新梢、枝条尺度或Y形果树的单侧开展了叶片与果实数量的调控处理。针对每组处理，记录成花诱导率与平均单果重。测定了茎尖分生组织(shoot apical meristems)中的赤霉素(Gibberellins)含量、各器官的光合速率以及非结构性碳水化合物(non-structural carbohydrate)浓度。结果显示，叶片存在与果实缺失可促进成花诱导，但该过程与分生组织内的非结构性碳水化合物含量无显著关联。这表明源自叶片与果实的促进与抑制信号，以及赤霉素介导的信号共同参与调控过程。不过，此类信号仅能在短距离内发挥作用，因为远距离处的叶片或果实存在对成花诱导无显著影响。与之相反，当树体内库需求(sink demands)失衡时，即使远距离处存在叶片，也会对果实生长产生影响，这表明碳水化合物可进行长距离运输。综上，本研究明确了器官间的相互依存关系与距离效应，进而明确了器官的自主程度——该自主程度似乎取决于所研究的具体过程：成花诱导或果实生长。