A Flower Specific Calcineurin B-Like Molecule (CBL)-Interacting Protein Kinase (CIPK) Homolog in Tomato Cultivar Micro-Tom ( Solanum lycopersicum L.)

Abstract

Floral and reproductive organs of higher plants are relatively sensitive to biotic and abiotic stresses compared with the vegetative organs. Calcineurin B-like molecule (CBL) interacting protein kinase (CIPK) has appeared to be involved in acquired tolerance and acclimation under environmental stresses such as salinity, drought and chilling. Semi-quantitative RT-PCR using the vegetative and reproductive organs of tomato Micro-Tom (Solanum lycopersicum L.) at the various developmental stages indicated that SlCIPK2 was expressed specifically in the floral organ. An anti-CIPK specific antibody recognized the recombinant SlCIPK2 specifically and cross-reacted to a CIPK-related polypeptide at a significant level in flower, particularly in stamen. The flower specific CIPK was tightly associated with the microsomes. In vitro pull-down assay of the recombinant SlCIPK2 showed that SlCIPK2 interacts with SlCBLs and stress-responsive transcription factors, SlERF7, SlCBF1 and SlAREB1. The present data suggested that the flower-specific CIPK, SlCIPK2, was involved in calcium signaling in tomato via CBLs and stress tolerance possibly mediated by the stress-responsive transcription factors in stamen.