TEMPRANILLO homologs in apple regulate flowering time in the woodland strawberry Fragaria vesca

Abstract

Many economically valuable fruit trees belong to the Rosaceae family. The long juvenile period of fruit trees makes their breeding costly and time-consuming. Therefore, flowering time regulation and shortening the juvenile phase have been a breeding priority for genetic improvement of fruit tree crops. TEMPRANILLO genes act as floral inhibitors in Arabidopsis and so, two orthologs of this gene were isolated here from apple (Malus domestica) and functionally analysed in Arabidopsis and woodland strawberry by being overexpressed in both model plants, and partially silenced in strawberry. The overexpression of MdTEM genes down-regulated FvFT1, FvGA3OX1, and FvGA3OX2 genes in strawberry. The overexpression lines exhibited delayed flowering, both in terms of days to flowering and the number of leaves at flowering. RNAi-mediated silencing of TEM resulted in early flowering plants. These plants flowered approximately five days earlier than wild type plants with a lower number of leaves. However, the overexpression of MdTEM genes could not functionally rescue the Arabidopsis mutants. According to the results, it can be concluded that MdTEM1 and MdTEM2 are orthologs of FvTEM gene, which play an important role in regulating the juvenile phase and flowering time through controlling FT and GA biosynthetic gene expression.