The identification and validation of interacting partners of an F-box protein in rice
Student name: Mr Shane William Rydquist
Guide: Dr Deepti Gupta
Year of completion: 2013
Host Organisation: Department of Plant Molecular Biology, University of Delhi South Campus
Supervisor (Host Organisation): Prof Jitendra P. Khurana
Abstract: The controlled and selective degradation of regulatory proteins plays a great role in plant development.
One such mechanism of turnover is the ubiquitin mediated 26S proteasome pathway. Among the many
components involved in this pathway, F-box proteins confer target specificity for ubiquitination. One such
F-box gene in rice, belonging to the FBK subfamily, was identified in our laboratory for functional
validation. To achieve this objective, homozygous RNAi as well as over-expression lines in rice were raised
previously. Among the phenotypic differences that were observed between these lines, the proliferation of
roots in the RNAi line was visibly greater as compared to the wild type. The over-expression lines on the
other hand showed a far less vigorous root phenotype. At the same time, this gene was found to express
preferentially in anther, based on microarray profiling. The focus of my study for the major project was to
identify and characterize interacting partners of this F-box protein. In this study, we have identified and
validated two interacting partners of this F-box protein in rice by library screening and validated their
interaction by BiFC assay and/or co-immunoprecipitation. The first is cinnamoyl coenzymeA reductase
(CCR) an enzyme involved in the lignin biosynthesis pathway, identified previously from screening an
anther cDNA library. The second partner was phytosulfokine receptor precursor (PSK-RP), identified from
a root cDNA library generated as a part of this study. Knowledge based on previous studies of CCR
suggests its probable role in lignification of the anther leading to its timely dehiscence. In the case of PSKRP,
its role in facilitating cell proliferation through the action of the mitogen, phytosulfokine remains to be
fully understood. Furthermore, these interactions with an F-box protein bring to light the possible role of
this F-box gene in anther and root development.
Key words: F-box, interacting partners, anther, root, development.
