Comparative Transcriptome Analysis of Different Actinidia arguta Fruit Parts Reveals Difference of Light Response during Fruit Coloration

SIMPLE SUMMARY: Kiwifruit (A. arguta) color is one of the most important quality characters. Exploring the coloration mechanism is significant for the genetic improvement of color quality and the breeding of new germplasms. As a critical environmental factor, light plays a key role in fruit coloration. However, the effecting mechanism of light on A. arguta coloration remains unclear. In current research, different A. arguta parts with different treatments were performed high throughput RNA sequencing, based on which candidate genes and corresponding annotations were obtained. Finally, AaMYB308like was screened as an R2R3-MYB typed TF involved in light-inducible fruit coloration through the result analysis of bioinformatics and molecular biology experiments. Our study provides insights into the photoreponse mechanisms in A. arguta coloration. ABSTRACT: Kiwifruit coloration is an important agronomic trait used to determine fruit quality, and light plays a vital role in the coloration process. The effect of light on fruit coloration has been studied in many species, but differences in the photoresponse of different fruit parts during fruit coloration is unclear in kiwifruit (Actinidia arguta). In this study, peel and core with bagging and non-bagging treatment at two stages were selected to perform high throughput RNA sequencing. A total of 100,417 unigenes (25,186 unigenes with length beyond 1000 bp) were obtained, of which 37,519 unigenes were annotated in functional databases. GO and KEGG enrichment results showed that ‘plant hormone signal transduction’ and ‘carbon metabolism’ were the key pathways in peel and core coloration, respectively. A total of 27 MYB-related TFs (transcription factors) were differentially expressed in peel and core. An R2R3-MYB typed TF, AaMYB308like, possibly served as a candidate objective, which played a vital role in light-inducible fruit coloration based on bioinformatics analysis. Transient overexpression of AaMYB308like suggested overexpression of AaMYB308like elevated transcription level of NtCHI in Nicotiana tabacum leaves. Integration of all these results imply that AaMYB308like might be served as a light-responsive transcription factor to regulate anthocyanin biosynthesis in A. arguta. Moreover, our study provided important insights into photoreponse mechanisms in A. arguta coloration.