Identification and characterization of Crocus sativus WRKY and its interacting MPK involved in crocins biosynthesis based on full-length transcriptome analysis

Crocus sativus, known as “plant gold”, is rich in carotenoids/apocarotenoids and possesses magnificent medicinal properties. Methyl jasmonate (MeJA) can remarkably enhance the production of carotenoids/apocarotenoids in C. sativus, but its regulatory network remains little understood. Herein, MeJA-induced saffron was sequenced using the combination of third generation long-read and next-generation short-read technology. A total of 75,649 high-quality non-redundant full-length transcripts were generated. Functional annotation of differentially expressed genes (DEGs) showed that post-translational modification was crucial to MeJA-induced saffron. In addition, most of the transcripts encoding enzymes in pathways were up-regulated which in accord with the increasing tendency of crocins content. Then 40 CsWRKYs, 19 CsMPKs were identified with in-depth sequence analysis and established the co-expression network of MPK-WRKY-enzyme through mathematical calculation. Finally, RT-qPCR was performed and a total of 2 CsWRKYs (CsWRKY38, 34) and 1 CsMPK (CsMPK6) with significant correlation were identified as good candidates for carotenoids/apocarotenoids biosynthetic regulation. Our results provide inspiration for blank research on post-translational modification of crocins biosynthesis in C. sativus.