Transgenic Phenotypic Differences of Grapevine Circular Rna Between Arabidopsis and Grapevine Callus Imply the Species-Dependent Functions of Vv-Circptcd1

Circular RNAs (circRNAs) served as covalently closed single-stranded RNAs have been proposed to influence plant development and stress resistance. Grapevine is the most economically valuable fruit crops cultivated worldwide and threaten by various abiotic stresses. Herein, we reported that a circRNA (Vv-circPTCD1) processed from the second exon of a pentatricopeptide repeat family gene PTCD1 was preferentially expressed in leaves and responded to salt and drought but not heat stress in grapevine. Additionally, the second exon sequence of PTCD1 was highly conserved but the biogenesis of Vv-circPTCD1 is species-dependent in plants. It was further found that the overexpressed Vv-circPTCD1 can slightly decreased abundance of the cognate host gene and the neighboring genes were barely affected in grapevine callus. Furthermore, we also successfully overexpressed the Vv-circPTCD1, and found that the Vv-circPTCD1 deteriorated the growth during heat, salt, and drought stresses in Arabidopsis. However, the biological effects on grapevine callus were not always consistent with that of Arabidopsis. Interestingly, we found that the transgenic plants of linear counterpart sequence also conferred the same phenotypes as that of circRNA during the three stress conditions, no matter what species. Those results imply that although the sequences are conserved, the biogenesis and functions of Vv-circPTCD1 are species-dependent. Our results indicate that the plant circRNA function investigation should be conducted in homologous species, which support valuable reference for further plant circRNA studies.