Crop biomass and yield are tightly linked to how the light signaling network translates information about the environment into allocation of resources, including photosynthates. Once activated, the phytochrome (phy) class of photoreceptors signal and re−deploy carbon resources to alter growth, plant architecture, and reproductive timing. Brassica rapa has been used as a crop model to test for conservation of the phytochrome−carbon network. B. rapa phyB mutants have significantly decreased or absent CO₂ −stimulated growth responses in seedlings, and adult plants have reduced chlorophyll levels, photosynthetic rate, stomatal index, and seed yield. Here, we examine the transcriptomic response of adult wild−type and BrphyB leaves to darkening and recovery in light. Three days of darkness was sufficient to elicit a response in wild type leaves suggesting a shift from carbon fixation and nutrient acquisition to active redistribution of cellular resources. Upon a return to light, wild−type leaves appeared to transcriptionally return to a pre−darkness state restoring a focus on nutrient acquisition. Overall, BrphyB mutant plants have a similar response with key differences in genes involved in photosynthesis and light response which deviate from the wild type transcriptional dynamics. Genes targeted to the chloroplast are especially affected. Adult BrphyB mutant plants had fewer, larger chloroplasts, further linking phytochromes, chloroplast development, photosynthetic deficiencies and optimal resource allocation.

中文翻译：

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BrphyB对成熟的芸s属植物叶片快速恢复到黑暗至关重要

作物生物量和产量与光信号网络如何将有关环境的信息转化为包括光合产物在内的资源分配紧密相关。激活后，光敏色素的植物色素（phy）类发出信号并重新部署碳资源，以改变生长，植物结构和生殖时间。甘蓝型油菜已被用作作物模型来测试植物色素碳网络的保存性。B. rapa phyB突变体在幼苗中的CO ₂刺激生长响应显着降低或不存在，成年植物的叶绿素水平，光合速率，气孔指数和种子产量降低。在这里，我们检查了成年野生型和BrphyB的转录组反应叶片变黑并在光照下恢复。三天的黑暗足以激发野生型叶片的响应，表明从碳固定和养分获取向细胞资源的主动再分配转变。在恢复光照后，野生型叶片似乎在转录上恢复了到黑暗前的状态，从而恢复了对养分获取的关注。总体而言，BrphyB突变体植物具有相似的响应，但其光合作用和光响应基因的关键差异与野生型转录动力学不同。靶向叶绿体的基因尤其受到影响。成人BrphyB 突变植物的叶绿体更少，更大，从而进一步联系了植物色素，叶绿体的发育，光合缺陷和最佳的资源分配。