Characterization of conserved circular RNA in polyploid Gossypium species and their ancestors

Abstract

Circular RNA (circRNA) is a regulatory class of long, noncoding RNA found in both plant and animal kingdoms. The profile and characterization of circRNA in cotton species remains to be explored. Here, using 24 rRNA-depleted RNA-seq libraries of putative diploid progenitors of Gossypium spp., Gossypium arboreum and Gossypium raimondii, their interspecies hybrid (F1) and allotetraploid Gossypium hirsutum, 1041, 1478, 1311, and 499 circRNAs were identified in each cotton species, respectively. A prevalence of 23 exon-circRNAs contain noncanonical GT/AG signals, and only ~ 10% of exon-circRNA is associated with reverse complementary intronic sequences. This result implies that plants employ a method of circRNA splicing distinct from that of animals. In addition, 432 circRNAs are stably expressed in multiple cotton species.