StPCP1: an IDD transcription factor involved in sugar-induced flowering and tuberization in Solanum tuberosum

在马铃薯植株(Solanum Tuberosum)中，开花和块茎形成都采用相似的诱导途径。由于马铃薯是作为地下贮藏器官而种植的，块茎形成时间和块茎产量在粮食安全方面具有越来越重要的意义，这就是为什么对影响块茎品质性状的块茎诱导因素和机制的识别在植物研究和农业中引起了广泛的兴趣。在这项建议中，我们建议在优先项目SPP1530的框架内对影响马铃薯开花和块茎形成的途径进行表征。开花和块茎是通过多因素途径调节的发育过程。我们特别感兴趣的是了解这些途径是如何与植物中的一般代谢过程汇合的。马铃薯POTATO1(StPCP1)蛋白是IDD转录因子家族中的一个转录因子。StPCP1 RNAi植株表现出开花和块茎形成的表型。初步的实时定量聚合酶链式反应分析表明，StPCP1是糖转运蛋白的一般调节者，从而影响马铃薯植株的碳水化合物状态。一些韧皮部移动信号被建议用来报告源叶向下沉器官如茎顶端分生组织或匍匐茎尖端的蔗糖状态。我们计划更详细地研究这些推测的韧皮部移动因子，特别是海藻糖6-磷酸、miR156和miR172以及它们的靶标。初步研究表明，叶片中的蔗糖含量反映在这些信号成分的表达和合成的变化上，正如在拟南芥中所显示的那样。我们进一步建议表征StPCP1作为转录因子的性质以及它的下游靶标。这特别涉及对蔗糖转运蛋白(如StSUT4)的直接调控，以及通过与已知ID1结构域的结合来调控更多的下游靶标。同时，我们将解决与马铃薯开花和块茎形成的已知信号通路相互作用的问题，即光周期和T6P通路，因为它们已经被证明受到StPCP1的影响。

In potato plants (Solanum tuberosum) both flowering and tuberization employ similar inducing pathways. Since potato is cultivated for its underground storage organs, the time to tuberization and the tuber yield is of growing significance in terms of food security, which is why the identification of tuber inducing factors and mechanisms also affecting tuber quality traits is of broadest interest in plant research and agriculture. In this proposal we suggest the characterization of pathways affecting flowering and tuberization in potato within the framework of the priority program SPP1530. Flowering and tuberization are developmental processes that are regulated via multifactorial pathways. We are especially interested in understanding how these pathways converge with general metabolic processes in the plant. The POTATO COUCH POTATO1 (StPCP1) protein is a transcription factor of the IDD transcription factor family. StPCP1 RNAi plants show a flowering and tuberization phenotype. Preliminary quantitative real time PCR analyses suggest that StPCP1 is a general regulator of sugar transporters thereby influencing the carbohydrate status in potato plants. Several phloem mobile signals have been suggested to report of the sucrose status of source leaves to sink organs such as the shoot apical meristem or the stolon tips. We plan on investigating these putative phloem mobile factors in more detail, in particular trehalose 6-phosphate, miR156 and miR172 as well as their targets. Preliminary studies indicate that the sucrose content in the leaves is reflected by a changed expression and syntheses of these signaling components, as it has been shown for Arabidopsis. We further propose characterizing the nature of StPCP1 as a transcription factor as well as its downstream targets. This specifically involves the direct regulation of sucrose transporters (e.g. StSUT4) and the regulation of further downstream targets via the binding of the known ID1 domain. At the same time we will address open questions regarding the interaction with known signaling pathways leading to flowering and tuberization in potato, i.e. the photoperiod and the T6P pathways, as they have been shown to be affected by StPCP1.