An Internal Motor Kinesin Is Associated with the Golgi Apparatus and Plays a Role in Trichome Morphogenesis inArabidopsis

Abstract

Members of the kinesin superfamily are microtubule-based motor proteins that transport molecules/organelles along microtubules. We have identified similar internal motor kinesins, Kinesin-13A, from the cotton Gossypium hirsutum and Arabidopsis thaliana. Their motor domains share high degree of similarity with those of internal motor kinesins of animals and protists in the MCAK/Kinesin13 subfamily. However, no significant sequence similarities were detected in sequences outside the motor domain. In Arabidopsis plants carrying the T-DNA knockout kinesin-13a-1 and kinesin-13a-2 mutations at the Kinesin-13A locus, >70% leaf trichomes had four branches, whereas wild-type trichomes had three. Immunofluorescent results showed that AtKinesin-13A and GhKinesin-13A localized to entire Golgi stacks. In both wild-type and kinesin-13a mutant cells, the Golgi stacks were frequently associated with microtubules and with actin microfilaments. Aggregation/clustering of Golgi stacks was often observed in the kinesin-13a mutant trichomes and other epidermal cells. This suggested that the distribution of the Golgi apparatus in cell cortex might require microtubules and Kinesin-13A, and the organization of Golgi stacks could play a regulatory role in trichome morphogenesis. Our results also indicate that plant kinesins in the MCAK/Kinesin-13 subfamily have evolved to take on different tasks than their animal counterparts.

Rho of Plant GTPase Signaling Regulates the Behavior of Arabidopsis Kinesin-13A to Establish Secondary Cell Wall Patterns

“…Although our experiments revealed that Kinsein-13A promotes microtubule depolymerization both in vitro and in vivo, previous articles reported that Kinesin-13A does not localize to cortical microtubules (Lu et al, 2005;Wei et al, 2009). We hypothesized that this apparent discrepancy is attributable to the absence or presence of MIDD1, which may contribute to the targeting of Kinesin-13a to microtubules in vivo.…”

“…In animals, members of the kinesin-13 family have microtubule depolymerization activity (Desai et al, 1999;Moores and Milligan, 2006). Although Kinesin-13A is involved in trichome morphogenesis (Lu et al, 2005), its molecular function in plant cells is currently unclear. In this study, we investigated the function of Kinesin-13A in metaxylem vessel cells.…”

A Class I ADP-Ribosylation Factor GTPase-Activating Protein Is Critical for Maintaining Directional Root Hair Growth in Arabidopsis

“…The extensive bundles of endoplasmic microtubules of agd1 mutants could also explain the abnormal Golgi movement at the root hair tip. In this regard, it was shown that Golgi stacks can interact with both microtubules and actin and that certain kinesins facilitate the dispersal of Golgi stacks in plant cells (Lu et al, 2005). Since ark1 root hairs exhibited bundled arrays of F-actin at the tip similar to agd1, both AGD1 and ARK1 may have common downstream targets that regulate cytoskeletal dynamics.…”

Actin bundling in plants

“…Shimmen [2007] has recently reviewed the 50 years of research establishing that the main motive force of cytoplasmic streaming is generated by the sliding of organelle-associated myosin XI along actin filaments. Although microtubules and their associated motors also contribute to intracellular movements in higher plant cells, they appear to be involved in short-distance movement and positioning of organelles at the cell cortex, rather than in long-distance or fast streaming [Van Gestel et al, 2002;Romagnoli et al, 2003Romagnoli et al, , 2007Lu et al, 2005].…”