TRANSCRIPTOME AND METABOLOME ANALYSIS OF CYTOKININ PATHWAY IN CICHORIUM ENDIVIA LEAVES

Endives (Cichorium endivia var. crispum) and escaroles (C. endivia var. latifolium) are leafy crops belonging to the Cichorieae tribe which leaves are widely consumed as fresh, minimally processed and cooked food. Similar to lettuce, endives and escarole leaves display a wide range of leaf morphology diversity, ranging from smooth (escaroles) to extremely curly leaves (endives). Cytokinins (CK) are plant hormones that occur naturally as N6-substituted adenine derivatives. CKs regulate several important aspects of plant development and growth such as cell division and differentiation, shoot development and organogenesis (Kieber and Shaller, The Arabidopsis book, 2014). Besides this, cytokinins control leaf shape determination and development (Frugis et al. Plant Physiol. 2001; Shani et al. Plant Cell 2010) and have long been known to inhibit leaf senescence (Gun and Amasino, Science 1995) in model and crop species (Ori at al. Plant Cell 1999; McCabe et al. Plant Physiol. 2001). Being potent general antagonists of senescence, cytokinins might be exploited to extend the shelf life properties of leafy vegetables. As for leaf patterning, cytokinin homeostasis and responses may contribute to leaf morphology diversity among Cichorium species and C. endivia cultivars. We reconstructed the genetic pathway of cytokinins in endives (reference cultivar Domari) which transcriptome was assembled de novo using RNA of several organs and Illumina HiSeq2000 technology. C. endivia genes involved in cytokinin metabolism, perception, signaling and response were identified, classified and annotated based on homology with the plant model species Arabidopsis thaliana. Transcript profiling of CK genes were analyzed in edible leaves of endive and escarole commercial cultivars and compared to CK metabolites content. Putative cultivar-specific transcriptional markers and SNPs were identified and characterized.