RNA interference-core proteins from the Actinidiaceae: Evolution, structure, and functional differentiation

As a popular berry fruit rich in vitamin C, kiwifruit (family Actinidiaceae) is economically important. RNA interference (RNAi) is one of the main mechanisms of plant resistance to viruses, and small RNAs also mediate growth, development, and resistance to stress and disease. The RNAi pathway involves three main types of proteins: Dicer-like (DCL), RNA-dependent RNA polymerase (RDR), and Argonaute (AGO). To gain a deeper understanding of small RNA formation and stress resistance mechanisms in kiwifruit, a comparative analysis of RNAi core gene regulatory families in Actinidiaceae was conducted. A total of 49, 20, and 111 RDR, DCL, and AGO genes were obtained from Actinidiaceae and initially corrected seven of them due to potential misannotation. These genes could be distinguished into four RDR, four DCL, and seven AGO protein classes and showed abundant subcellular localization and structural variation characteristics. Furthermore, the potential evolution of these RNAi-related genes was preliminarily characterized and clarified their unique expression profiles in tissues (expression patterns in different tissues and potential differences in gene expression between species) and in response to stresses (pathogen induction and storage). In conclusion, in this study, a systematic identification and comparative analysis of the RNAi core protein regulator family of Actinidiaceae was performed, and expression analysis was conducted on Actidia chinensis. These results are expected to reveal the evolutionary trends of the RNAi core protein family of Actinidiaceae and provide a reference for the evolutionary process of natural differences in sRNA formation and stress resistance in kiwifruit.