AimsGeophytic plants have evolved to develop underground storage organs (USO) in the active growing season to withstand harsh environments as well as to coordinate growth and reproduction when conditions are favourable. Saffron is an autumn flowering geophyte and an expensive spice crop restricted to certain geographical locations in the world. Saffron, being sterile, does not produce seeds and thus propagates only through corms, the quality of which determines its yield. Corm development in saffron is unexplored and the underlying molecular mechanism is still elusive. In this study, we performed an extensive characterisation of the transcriptional dynamics in the source (leaf) and sink (corm) tissues during corm development in saffron.Key resultsVia morphological and transcriptome studies, we identified molecular factors regulating corm development process in saffron, which defined corm development into three stages: the initiation stage demonstrates enhanced vegetative growth aboveground and swelling of shoot base belowground due to active cell division & carbohydrate storage; the bulking stage comprises of increased source and sink strength, active photosynthesis, circadian gating and starch accumulation; the maturation stage represents reduced source and sink strength, lowered photosynthesis, sugar transport, starch synthesis and cell cycle arrest.UtilityThe global view of transcriptional changes in source and sink identifies similar and new molecular factors involved in the saffron corm development process compared to USO formation in other geophytes and provides a valuable resource for dissecting the molecular network underlying the corm development. We propose a hypothetical model based on data analysis, of how molecular factors via environmental cues can regulate the corm development process in saffron.

中文翻译：

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源库组织的转录动力学确定了调节藏红花球茎发育过程的分子因素（Crocus sativus L.）

目的地球植物已经进化为在活跃的生长季节发育出地下储存器官（USO），以承受恶劣的环境，并在条件有利时协调生长和繁殖。藏红花是一种秋季开花的土生植物，也是一种昂贵的香料作物，仅限于世界某些地理位置。藏红花是不育的，不会产生种子，因此只能通过球茎繁殖，球茎的质量决定其产量。藏红花球茎的发育尚未被探索，其潜在的分子机制仍然难以捉摸。在这项研究中，我们对藏红花球茎发育过程中源（叶）和库（球茎）组织的转录动力学进行了广泛的表征。主要结果通过形态学和转录组研究，我们确定了调节藏红花球茎发育过程的分子因子，其中将球茎发育定义为三个阶段：起始阶段表现出由于活跃的细胞分裂和碳水化合物储存，地上营养生长增强和地下芽基部膨胀；膨胀阶段包括增加源和库强度、活跃的光合作用、昼夜节律门控和淀粉积累；成熟阶段代表源和库强度降低，光合作用、糖运输、淀粉合成和细胞周期停滞降低。实用性源和库转录变化的全局视图识别了与 USO 形成相比藏红花球茎发育过程中涉及的相似和新的分子因子在其他地球植物中，并为剖析球茎发育背后的分子网络提供了宝贵的资源。我们提出了一个基于数据分析的假设模型，说明分子因素如何通过环境线索调节藏红花的球茎发育过程。