2019 ASHS Annual Conference

Auxin response factors (ARFs) are involved in auxin mediated transcriptional regulation in plants. We study the roles of ARFs in the regulation of fruit quality in tomato. We found that both tomato SlARF6 and SlARF10 were located in the nucleus and displayed transcriptional activity. Overexpression of SlARF6 and SlARF10 increased chlorophyll contents in tomato fruits, whereas down-regulation resulted in decreased chlorophyll contents compared with wild type (WT) plants. Furthermore, up-regulation of SlARF6 and SlARF10 increased the photosynthetic rate, accumulation of starch and soluble sugars, whereas knock-down led to opposite phenotypes in tomato. RNA-sequence analysis showed that regulation of SlARF6 expression altered the expression of genes involved in chlorophyll metabolism, photosynthesis and sugar metabolism. SlARF6 protein directly bound to the promoter of SlGLK1, CABs and RbcS genes and positively regulated the expression of these genes. SlARF6 also played a role in the regulation of fruit ripening and ethylene production, by directly binding to SAMS1 promoter and negatively regulated the SAMS1 expression. Taken together, our study demonstrates that ARFs play an important role in the regulation of chlorophyll biosynthesis, photosynthesis, sugar accumulation and fruit development in tomato and provides a potential target for genetic engineering to improve fruit nutrition in horticulture crops.