Instituto de Ciencias Biológicas, Universidad de Talca, 2 Norte 685, Talca, Chile.
New Zealand Institute for Plant and Food Research Limited, Mt. Albert Research Centre, Auckland, 1025, New Zealand.
Sci Rep. 2018 Jul 12;8(1):10524. doi: 10.1038/s41598-018-28226-y.
Fragaria chiloensis is a strawberry endemic from Chile with attractive white-pink fruit, pleasant aroma and taste. However, this fruit has a limited post-harvest period due to fast softening. Several transcription factors (TFs) are involved in the regulation of fruit ripening, and members of the NAC family have been implicated in cell wall remodeling. FcNAC1 was isolated from F. chiloensis fruit, coding a protein of 332 amino acid residues and displaying a characteristic NAC domain at the N terminus. FcNAC1 protein showed nuclear localization. An increase in transcript level was observed during ripening. A sequence of 1488 bp of FcNAC1 promoter was obtained. In silico analysis identified cis elements able to respond to some hormones and Secondary wall NAC binding elements (SNBE), and responding to auxin and ABA. A structural model of FcNAC1 provided evidence for interaction with DNA sequences containing SNBE, while a dual luciferase assay confirmed the transcriptional activation by FcNAC1 of the promoter of FcPL, a gene involved in cell wall remodeling in F. chiloensis fruit. The results suggest the participation of FcNAC1 during ripening development of strawberry fruit, by regulating pectin metabolism during softening.
智利草莓是智利特有的一种草莓，具有吸引人的白色到粉红色的果实、宜人的香气和味道。然而，由于果实迅速软化，这种水果的收获后保质期有限。几种转录因子（TFs）参与了果实成熟的调控，而 NAC 家族的成员则与细胞壁重塑有关。FcNAC1 从智利草莓果实中分离出来，编码一个由 332 个氨基酸残基组成的蛋白质，并在 N 端显示出一个特征性的 NAC 结构域。FcNAC1 蛋白显示核定位。在成熟过程中观察到转录水平增加。获得了 1488bp 的 FcNAC1 启动子序列。通过计算机分析鉴定出能够响应一些激素和次生壁 NAC 结合元件（SNBE）的顺式元件，并响应生长素和 ABA。FcNAC1 的结构模型为与含有 SNBE 的 DNA 序列相互作用提供了证据，而双荧光素酶测定证实了 FcNAC1 对参与智利草莓果实细胞壁重塑的 FcPL 基因启动子的转录激活。这些结果表明，FcNAC1 通过调节软化过程中的果胶代谢，参与了草莓果实成熟发育的过程。
