A dominant mutation of TWISTED DWARF 1 encoding an .ALPHA.-tubulin protein causes severe dwarfism and right helical growth in rice

Abstract

Dwarfism is a common type of mutation in many plant species. The pathways and factors regulating biosynthesis and signaling of several plant growth regulators have been clarified through analyses of dwarf mutants in rice, Arabidopsis, pea, and maize. However, the genetic mechanisms controlling dwarfism are not well characterized, and the causal genes underlying most dwarf mutants are still uncovered. Here, we report a dominant mutant, Twisted dwarf 1-1 (Tid1-1), showing dwarfism and twisted growth in rice. Tid1-1 exhibit right helical growth of the leaves and stem and shortening of the roots. They also show an increased number of cells in the shoot apical meristem. Cells in the leaves of Tid1-1 are often ill-shapen, possibly owing to irregular cell division. Cell elongation in roots is suppressed in the elongation zone, and cells in the root apical meristem are enlarged. Map-based cloning of TID1 revealed that it encodes an α-tubulin protein comprising microtubules and is an ortholog of Arabidopsis LEFTY genes. Our analysis of the Tid1-1 mutant revealed that the dynamics of microtubules affects not only anisotropic growth in both dicots and monocots, but also meristematic activity and gross plant morphology.

POM-POM2/CELLULOSE SYNTHASE INTERACTING1 Is Essential for the Functional Association of Cellulose Synthase and Microtubules inArabidopsis

“…Although cellulose-deficient mutants (i.e., mutants that have reduced CESA velocities and cellulose content) typically display defects in microtubule organization (Paredez et al, 2008), no spiraling phenotypes have been reported. Moreover, clasp and other microtubule-related mutants also affect mitotic activity, presumably by disturbances in the mitotic spindle formation (Ambrose et al, 2007;Kirik et al, 2007;Sunohara et al, 2009). Interestingly, pom2/csi1 mutants also held a reduced number of cells that actively divided in the root meristem.…”

“…Apart from altered microtubule organization, mutations in several microtubule-associated genes also lead to reduced mitotic activity (Ambrose et al, 2007;Kirik et al, 2007;Sunohara et al, 2009). To test whether the pom2 mutants also hold fewer cells that actively divide, we crossed lines expressing the mitotic marker cycB1;1:Cyclin Destruction Box (CDB):b-glucuronidase (GUS) (Hauser and Bauer, 2000) with several pom2 mutant alleles.…”

RICE MORPHOLOGY DETERMINANTEncodes the Type II Formin FH5 and Regulates Rice Morphogenesis

“…In response to environmental and developmental stimuli, the microtubule system can be reoriented, such as undergoing clockwise or counterclockwise rotation in plant cells (Lloyd and Chan, 2004;Chan et al, 2007). In plants, components of the microtubule system have been shown to be critical for plant architecture (Thitamadee et al, 2002;Twell et al, 2002;Nakajima et al, 2004;Sedbrook, 2004;Sunohara et al, 2009). For example, the rice TWISTED DWARF1 (TID1) gene encodes an a-tubulin that influences plant morphology; a dominant mutation of TID1 caused disrupted cellular microtubule arrays, severe dwarfism, and right helical growth (Sunohara et al, 2009).…”

Isolation and Characterization of a Dominant Dwarf Gene, D-h, in Rice

“…The gene for the semi-dominant, gain-of-function mutant Slr-d , located on chromosome 3, is a consequence of a mutation in the gene encoding the rice DELLA protein SLR1 , which functions as a repressor of GA signaling through an interaction with the GA receptor GID1 [7]. The gene for another dominant dwarf mutant, Twisted dwarf 1 ( Td1 ), was located on chromosome 11 and was found to encode the α-tubulin protein; this has been recognized as an additional factor that determines plant height through the regulation of microtubule formation [16]. The loci for other dominant dwarf mutants, including D53 , Ssi1 , Sdd(t) , Dx , and LB4D , were identified on chromosomes 11, 1, 6, 8, and 11, respectively [13]–[15], [17], [18].…”