Аннотация:Summary The Phalaenopsis orchid produces complex flowers that are commercially valuable, which has promoted the study of its flower development. E‐class MADS ‐box genes, SEPALLATA ( SEP ), combined with B‐, C‐ and D‐class MADS ‐box genes, are involved in various aspects of plant development, such as floral meristem determination, organ identity, fruit maturation, seed formation and plant architecture. Four SEP ‐like genes were cloned from Phalaenopsis orchid, and the duplicated Pe SEP s were grouped into Pe SEP 1/3 and Pe SEP 2/4 . All Pe SEP s were expressed in all floral organs. Pe SEP 2 expression was detectable in vegetative tissues. The study of protein–protein interactions suggested that Pe SEP s may form higher order complexes with the B‐, C‐, D‐class and AGAMOUS LIKE 6‐related MADS ‐box proteins to determine floral organ identity. The tepal became a leaf‐like organ when Pe SEP 3 was silenced by virus‐induced silencing, with alterations in epidermis identity and contents of anthocyanin and chlorophyll. Silencing of Pe SEP 2 had minor effects on the floral phenotype. Silencing of the E‐class genes Pe SEP 2 and Pe SEP 3 resulted in the downregulation of B‐class Pe MADS 2‐6 genes, which indicates an association of Pe SEP functions and B‐class gene expression. These findings reveal the important roles of Pe SEP in Phalaenopsis floral organ formation throughout the developmental process by the formation of various multiple protein complexes.
