Abstract In some growing environments blueberry (Vaccimium corymbosum L.) yields exhibit excessive annual variation associated with poor photosynthetic performance. The purpose of this study was to determine how photosynthesis may be affected by demand and to define the mechanisms underpinning photosynthetic plasticity. Manipulation of source-sink ratios revealed that yields were maintained following 50 % defoliation. This was associated with an adaptive increase in photosynthetic capacity mediated via changes in stomatal physiology, photosynthetic electron transport and CO2 assimilation. Transcripts encoding enzymes of the Calvin-Benson cycle including the Rubisco large subunit, Rubisco activase, phosphoribulokinase and plastid-localised glyceraldehyde phosphate dehydrogenase 3 were more abundant in leaves from partially defoliated plants relative to control plants. Short-term 13CO2 labelling experiments suggested that partial defoliation did not incur an assimilation penalty although the accumulation of sugars and starch in some organs was reduced. Metabolite profiles of leaves from partially defoliated plants exhibited some differences from those of control leaves, however, no changes in the diurnal content of leaf sugar and starch were observed between treatments. The data highlights the mechanisms by which blueberry leaves adapt to increased demand and demonstrate that photosynthetic plasticity can compensate for significant loss of the photosynthetic area.

中文翻译：

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光合可塑性允许蓝莓 (Vaccinium corymbosum L.) 植物在高汇需求条件下补偿产量损失

摘要 在某些生长环境中，蓝莓 (Vaccimium corymbosum L.) 的产量表现出与光合性能差相关的过度年变。本研究的目的是确定光合作用如何受到需求的影响，并确定支持光合作用可塑性的机制。对源汇比率的操纵表明，在 50% 的落叶后产量保持不变。这与通过气孔生理、光合电子传递和 CO2 同化的变化介导的光合能力的适应性增加有关。编码卡尔文-本森循环酶的转录本，包括 Rubisco 大亚基、Rubisco 激活酶、与对照植物相比，部分脱叶植物的叶子中的磷酸核糖激酶和质体定位的磷酸甘油醛脱氢酶 3 含量更高。短期 13CO2 标记实验表明，尽管某些器官中糖和淀粉的积累减少了，但部分落叶并未引起同化惩罚。部分落叶植物叶片的代谢物谱与对照叶片的代谢物谱显示出一些差异，然而，在处理之间观察到叶片糖和淀粉的昼夜含量没有变化。数据突出了蓝莓叶适应需求增加的机制，并证明光合可塑性可以弥补光合面积的显着损失。短期 13CO2 标记实验表明，尽管某些器官中糖和淀粉的积累减少了，但部分落叶并未引起同化惩罚。部分落叶植物叶片的代谢物谱与对照叶片的代谢物谱显示出一些差异，然而，在处理之间观察到叶片糖和淀粉的昼夜含量没有变化。数据突出了蓝莓叶适应需求增加的机制，并证明光合可塑性可以弥补光合面积的显着损失。短期 13CO2 标记实验表明，尽管某些器官中糖和淀粉的积累减少了，但部分落叶并未引起同化惩罚。部分落叶植物叶片的代谢物谱与对照叶片的代谢物谱显示出一些差异，然而，在处理之间观察到叶片糖和淀粉的昼夜含量没有变化。数据强调了蓝莓叶适应需求增加的机制，并证明光合可塑性可以弥补光合面积的显着损失。然而，在处理之间没有观察到叶糖和淀粉的昼夜含量变化。数据突出了蓝莓叶适应需求增加的机制，并证明光合可塑性可以弥补光合面积的显着损失。然而，在处理之间没有观察到叶糖和淀粉的昼夜含量变化。数据突出了蓝莓叶适应需求增加的机制，并证明光合可塑性可以弥补光合面积的显着损失。