Initiation of organ maturation and fruit ripening in grapevine is controlled by the CARPO-NAC transcription factor [Sultana]. Initiation of organ maturation and fruit ripening in grapevine is controlled by the CARPO-NAC transcription factor [Sultana]

In this study we identified the NAC family member VviCARPO (Controlled Adjustment of Ripening and maturation of Plant Organs) as a key regulator of grapevine maturation. We explored CARPO binding landscapes through DAP-seq and overlapped its bound genes with transcriptomics datasets from stable and transient CARPO overexpressing grapevine plants to narrow a set of high-confidence targets. Among these, we identified key molecular ripening markers. Physiological, metabolic and promoter activation analyses showed that CARPO induces chlorophyll degradation and anthocyanin accumulation through the up regulation of VviSGR1 and VviMYBA1, respectively, with the latter being up-regulated by a VviCARPO-VviNAC03 regulatory complex. CARPO complemented the nor mutant phenotype in tomato, suggesting it may have acquired a dual role as an orchestrator of both ripening- and senescence-related processes. Our results evidenced that CARPO is a master regulator of the grapevine vegetative-to-mature phase organ transition and therefore an essential target for insuring fruit quality and environmental resilience. Overall design: For transient transformation of Vitis vinifera cv. Sultana, the 35S:VviCARPO construct was transferred to Agrobacterium tumefaciens strain C58C1 by electroporation. As control, Agrobacterium was also transformed with an empty pK7WG2 containing a non-coding sequence. Seven in vitro six-week-old plants of grapevine cv. Sultana for overexpression and five for the control were immersed in each bacterial suspension and vacuum infiltrated (2 X 2 min at 90kPa). After agroinfiltration, plantlets were allowed to recover in vitro for seven days before collecting material for RNA extraction and transcriptomic analysis.

本研究中，我们鉴定出NAC家族成员VviCARPO（植物器官成熟与衰老精准调控因子，Controlled Adjustment of Ripening and maturation of Plant Organs）作为葡萄成熟的关键调控因子。我们通过DNA亲和纯化测序（DAP-seq）解析了CARPO的全基因组结合图谱，并将其结合基因与稳定及瞬时过表达（overexpression）CARPO的葡萄植株的转录组学（transcriptomics）数据集进行交集分析，以筛选出一组高可信度的靶标基因。在这些靶标中，我们鉴定出了关键的果实成熟分子标记物。生理、代谢及启动子激活分析显示，CARPO分别通过上调VviSGR1和VviMYBA1来诱导叶绿素降解与花青素积累，其中VviMYBA1的上调由VviCARPO-VviNAC03调控复合物介导。CARPO能够互补番茄nor突变体的表型，这表明其可能兼具调控果实成熟与器官衰老相关过程的双重功能。本研究结果证实，CARPO是调控葡萄营养生长向成熟阶段器官转变的核心调控因子，因此是保障果实品质与环境适应性的关键靶点。实验总体设计：针对‘无核白’（Vitis vinifera cv. Sultana）葡萄的瞬时转化实验，我们通过电转化（electroporation）将35S:VviCARPO重组载体导入根癌农杆菌（Agrobacterium tumefaciens）菌株C58C1中。作为对照，我们同时将携带非编码序列的空载pK7WG2载体导入根癌农杆菌中。取7株生长6周的离体‘无核白’葡萄组培苗用于过表达组，5株用于对照组，将其分别浸没于菌液中并进行真空渗透处理（90kPa下真空渗透2次，每次2分钟）。农杆菌浸润处理后，将组培苗在离体培养条件下恢复培养7天，随后收集材料用于RNA提取（RNA extraction）与转录组分析（transcriptomic analysis）。