Early flowering in Fragaria vesca through gene silencing

The diploid strawberry has been recognized as a model plant for genomics research in Rosaceae family. Many economically valuable fruit trees belong to Rosaceae family; the long juvenile period of fruit trees makes their breeding costly and time-consuming. Therefore, shortening the juvenile phase is always an imperative breeding goal. TEMPRANILLO gene has been proposed to delay flowering time through FT repression, to this end, we hypothesized that it’s silencing would cause early flowering. In the present study, a 137bp fragment of TEM gene was cloned into pHellsgate12 binary Gateway® destination vector under control of the CaMV35S promoter and octopine synthase terminator. Vector included two introns to form a hairpin RNA to trigger gene silencing. Fragaria vesca L. (Hawaii-4) leaf explants were used for transformation by Agrobacterium tumefaciens strain GV310 containing the RNAi silencing construct. Real-time PCR analysis revealed the reciprocal changes in mRNA expression of TEM and FT. As expected, the expression of endogenous TEM suppressed in the transgenic lines; while the expression level of FT increased indicating the precocious flowering. Transgenic lines flowered 24 days after transferring to the inductive conditions, but the control plants flowered after 32 days. In addition, the average number of leaves at the flowering time in transgenic lines and control plants were 4.5 and 8.2, respectively. Based on our findings we suggest that TEM plays a key role in regulating the juvenile phase and flowering time in the plants.

Keywords:

Fragaria vesca , gene silencing , TEMPRANILLO , flowering