Functional Studies Of Solanum Lycopersicum Auxin Response Factor 6 (SlARF6) In Fruit Initiation And Development

Tomato(Solanum lycopersicum L.) is not only the representative crop of solanaceous plants but the model plant for the study of fruit initiation and development. ARFs are important auxin response factors, which are encoded by a family gene of transcription factor that control auxin-dependent developmental processes specifically. In recent years, it has been reported that some AFRs family members participate in the initiation and development of tomato fruit.We found that SlARF6 is expressed in all tomato organs and tissues by using TomExpress database analysis, and SlARF6 has high expression levels in stems, flowers as well as fruits. And then, qRT-PCR assay showed the same result. The physiological function of SlARF6 in tomato development was studied through RNA interference, and the SlARF6 down-regulated plants had seedless fruits because of the reduction in recongnition capacity between pollen tubes and ovules. RNA-sequencing(RNA-Seq) identified 72 differentially expressed genes(DEGs) involved in the metabolism and signaling transduction of many phytohormone such as auxin, GA3 and ethylene. And there are also 61 transcription factors(TFs) encoded 61 differential expression genes, which belong to 25 TF families. These DEGs may regulate or influence the fertilization of pollen tubes and ovules. Over-expression of SlARF6 in tomato produces a higher concentration of chlorophyll in green fruit than wild type plants. It suggests that SlARF6 is involved in the chlorophyll biosynthesis of tomato fruits.Our study demonstrates that SlARF6 plays an important role in fruit initiation and development, and, ARFs displays variety of function in gowth and development in tomato plants.