G proteins are the key regulators for a wide range of cellular processes
in animals and plants. In comparison to animals and yeast, plants have a
single Rho-GTPase subfamily called Rho-like GTPases (ROPs). The ROP
family of monomeric GTPases has emerged as a versatile and key regulator
in plant signal transduction processes. During the past few years'
studies on plant RHO-type (ROP) GTPase have generated new insights into
their role in diverse processes ranging from cytoskeletal organization,
polar growth, development to stress and hormonal responses. Studies have
shown that plants have evolved specific regulators and effector
molecules. ROP GTPases possess the ability to interact with these
multiple regulator and effector molecules that ultimately determines
their signaling specificity. Recently, genome wide studies in plants
have shown that the Arabidopsis genome encodes 93, and rice has nearly
85 small GTPase homologs. And we have been able to identify four new
homologs in the rice genome. Here, we focus on the complete
phylogenetic, domain, structural and expression analysis during stress
and various developmental processes of small GTPases in plants. The
comparison of gene expression patterns of the individual members of the
GTPase family may help to reveal potential plant specific signaling
mechanisms and their relevance. Also, we are summarizing the role of
currently known ROP GTPases and their interacting proteins with brief
description, simultaneously, comparing their expression pattern based on
microarray data. Overall, we will be discussing the functional genomic
perspective of plant Rho like GTPases and their role in regulating
several physiological processes such as stress, hormonal, pollen tube,
root hair-growth and other developmental responses.
