RESUMEN
Plants have evolved phosphate (Pi) starvation response to adapt the low-Pi environment. The regulation of adaptive responses to phosphorus deficiency by the PHR1-miR399-PHO2 module has been well studied in Arabidopsis thaliana but not in strawberry. Transcription factor PHR1 as the central regulator in the Pi starvation signaling has been revealed in a few plant species. However, the function of PHR1 homologues in strawberry is still unknown. In this study, a total of 13 MYB-CC genes were identified in the woodland strawberry (Fragaria vesca) genome and the FvPHR1 gene was characterized. FvPHR1 contains MYB domain and coiled-coil (CC) domain and is localized in the nucleus. FvPHR1 also exhibits trans-activation ability. Furthermore, the P content in leaves of FvPHR1-overexpressing woodland strawberries was significantly increased by 1.38-fold to 1.78-fold compared with that in the wild type. FvPHR1 was also demonstrated to directly bind to the FvMIR399a promoter and positively regulate the expression of FvmiR399a in woodland strawberry. These results showed that PHR1-miR399 module is involved in the regulation of phosphate-signaling pathway and phosphate homeostasis in woodland strawberry.
Asunto(s)
Fragaria/genética , Regulación de la Expresión Génica de las Plantas , MicroARNs/genética , Fosfatos/metabolismo , Transducción de Señal , Factores de Transcripción/metabolismo , Secuencia de Aminoácidos , Núcleo Celular/metabolismo , Fragaria/fisiología , Expresión Génica , Homeostasis , Modelos Biológicos , Fósforo/deficiencia , Filogenia , Hojas de la Planta/genética , Hojas de la Planta/fisiología , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Modificadas Genéticamente , Regiones Promotoras Genéticas/genética , ARN de Planta/genética , Alineación de Secuencia , Factores de Transcripción/genéticaRESUMEN
Fruit quality is an important trait in strawberry and is determined by many factors. The soluble solid content in strawberry fruits is positively related to the phosphorus content. MicroRNA399 (miR399) is involved in the regulation of phosphate (Pi) homeostasis. However, the effect of miR399 on strawberry quality remains unknown. In this study, miR399a-overexpressing transgenic woodland strawberries (Fragaria vesca) were obtained via an Agrobacterium-mediated transformation. The phosphorus (P) content was 1.1-fold to 2.1-fold higher in the leaves and fruits of the miR399a-overexpressing plants than in the wild type (WT). However, the P content in the miR399a-overexpressing plants was decreased by 25% to 45% in the roots. The primary root length of the transgenic lines in both the high-Pi and low-Pi media was shorter than that of the WT. Interestingly, the transgenic lines in pots under Pi-sufficient conditions grew better than the WT, and the fruit quality, including the contents of fructose and glucose and soluble solid, was significantly higher in the transgenic lines than in the WT. The overexpression of miR399a in strawberry can be used to improve the parameters involved in fruit quality and provides information regarding breeding nutrient-improved strawberry.