Identification and Characterization of SPL Transcription Factor Family Reveals Organization and Chilling-Responsive Patterns in Cabbage (Brassica oleracea var. capitata L.).

Squamosa promoter-binding protein-like (SPL) is a major family of plant-specific transcription factor, which is involved in multiple biological processes, such as plant growth and development, hormone response, light response and stress response. Therefore, it has been profoundly significant to systematically analyze the SPL Transcription Factors family in Brassica oleracea. In this study, a total of 33 BoSPLs were identified in the B. oleracea genome, and they were further divided into six subgroups based on the phylogenetic tree constructed from the SPL proteins of B. oleracea, B. rapa and Arabidopsis thaliana. The expression profile of BoSPLs in different organs/tissues showed that a large number of BoSPLs were expressed in the callus, root, stem, leaf, bud, flower and silique. In addition, the expression levels of two BoSPLs (BoSPL9b and BoSPL10b) were up-regulated in chilling tolerance cabbage 'CT-923' at 6 h after chilling stress when compared with normal treatment (mock), while two BoSPLs (BoSPL9b and BoSPL15a) in chilling sensitive cabbage 'CS-D9', five BoSPLs (BoSPL1, -9a, -9b, -10b, -11b) in 'CT-923' and two BoSPLs (BoSPL9b and BoSPL16a) in 'CS-D9' were up-regulated after 24 h chilling stress, indicated that these genes may play an important role in the chilling-tolerance of cabbage. We analyzed the characteristics of BoSPLs and provided the basis for further functional research. [ABSTRACT FROM AUTHOR]