Identification and Functional Characterization of a Microtubule-Associated Protein, GhCLASP2, From Upland Cotton (Gossypium hirsutum L.)

Abstract

Cytoplasmic linker-associated proteins (CLASPs) are microtubule-associated proteins (MAPs) involved in regulation of dynamics of microtubules (MTs) that play an important role in plant growth and development. In this study, we identified cotton <i>CLASP</i> genes and investigated the function of <i>GhCLASP2</i>. <i>GhCLASP2</i> was mainly expressed in stem and developing fibers, especially in fibers of the secondary cell wall deposition stage. Ectopic expression of <i>GhCLASP2</i> in <i>Arabidopsis</i> increased the branching number of leaf trichomes and rescued the defective phenotypes of <i>clasp-1</i>. In cotton, overexpression of <i>GhCLASP2</i> increased fiber strength, probably related to enhanced expression levels of tubulin, cellulose synthase, and expansin genes. Suppression of <i>GhCLASP2</i> caused shorter internodes and semi-dwarfism, abnormal flower stigma, aborted anthers without pollen grains, and sterility. These changed phenotypes were similar to those observed in the <i>Arabidopsis clasp-1</i> mutant. GhCLASP2 was co-localized with MTs according to transient experiment. These results suggest that <i>GhCLASP2</i> functions similarly as <i>AtCLASP</i>, acting as a MAP and controlling cotton growth and development by regulating MTs.