Date Published: May 23, 2019
Publisher: Public Library of Science
Author(s): Yukuo Li, Wen Cui, Ran Wang, Miaomiao Lin, Yunpeng Zhong, Leiming Sun, Xiujuan Qi, Jinbao Fang, Shin-Han Shiu.
As important regulators, miRNAs could play pivotal roles in regulation of fruit coloring. Actinidia arguta is a newly emerged fruit tree with extensively application prospects. However, miRNAs involved in A. arguta fruit coloring are unknown. In this study, A. arguta fruit were investigated at three developmental stages by small RNAs high-throughput sequencing. A total of 482 conserved miRNAs corresponding to 526 pre-miRNAs and 581 novel miRNAs corresponding to 619 pre-miRNAs were grouped into 46 miRNA families. Target gene prediction and analysis revealed that miR858, a strongly candidate miRNA, was involved in anthocyanin biosynthesis in which contributes to fruit coloring. The anthocyanin level was determined in three A. arguta cultivars by UPLC-MS/MS (ultra-performance liquid chromatography coupled with tandem mass spectrometry). In addition, qPCR (quantitative real-time PCR), cluster analysis were conducted as well as correlation analysis. All results were combined to propose a model in which describes an association of miRNA and anthocyanin biosynthesis in A. arguta. The data presented herein is the first report on miRNA profile analysis in A. arguta, which can provide valuable information for further research into the regulation of the miRNAs in anthocyanin biosynthesis and fruit coloring.
Domestication of kiwifruit (genus Actinidia, Actinidiaceae) began in the twentieth century . It is known as the ‘king of fruits’ as it contains high contents of amino acids, mineral components, antioxidants, vitamin C and abundant dietary fiber . Kiwifruit belongs to the genus of Actinidia and comprises approximately 54 species and 125 taxa . Commercial cultivars are mainly selected from two species: Actinidia chinensis and Actinidia deliciosa due to their unique taste, large-fruit and long-storage . Kiwifruit is traditionally known as a green-fleshed fruit for a long time until the release of yellow-fleshed kiwifruit. Recently, an all-red-fleshed kiwifruit (A. arguta) which appears in the red skin and the flesh is introduced to the market. Consumers are attacted by its unique desirable agro characteristics such as appearance and high level of anthocyanin.
MiRNAs are important regulators involved in various biological processes, including biotic and abiotic stress tolerance, plant growth and development, metabolic pathways and morphogenesis,. Extensive reports show that miRNAs regulate fruit development in multiple plants, including orange , pear , tomato , and persimmon . Although many miRNAs have been identified by small RNA sequencing in both model plants and many fruit trees including Arabidopsis thaliana , tomato , rice , apple  and peach , miRNAs have not been characterized in A. arguta. The results of our previous study suggests that anthocyanin accumulation in A. arguta during fruit development is accompanied by the expression of relevant gene, indicating that fruit coloring is both a dynamical process and a complex network regulated by a series of genes [48, 59]. Therefore, the identification of miRNAs in A. arguta can provide valuable information to better understand the biological process in fruit coloring.