Abstract
Cytoskeletal remodeling has a fundamental role, especially during transitional developmental stages when cells rapidly adopt new forms and roles, like gametogenesis, fertilization and concomitant embryogenesis and seed formation. KATANIN 1, a microtubule severing protein, fulfills a major regulatory mechanism of dynamic microtubule turnover in eukaryotes. Herein, we show that three well-established KATANIN 1 mutants, fra2, lue1 and ktn1-2 collectively display lower fertility and seed set in Arabidopsis. These lower fertility and seed set rates of fra2, lue1 and ktn1-2 mutants were correlated to abnormalities in the development of embryo proper and seed. Such phenotypes were rescued by transformation of mutants with functional pKTN1::GFP:KTN1 construct. This study significantly expands the already broad functional repertoire of KATANIN 1 and unravels its new role in embryo and seed development. Thus, KATANIN 1 significantly contributes to the fertility and proper embryo and seed formation in Arabidopsis.
Highlights
In angiosperms, seeds arise from a fertilized ovule and consist of the following parts: the embryo which arises from the zygote, the endosperm which arises from the fertilization of the diploid central cell by haploid sperm cell and the integuments
All KATANIN 1 mutants showed reduced fertility, which is evident by the formation of numerous non-elongating siliques on the inflorescences of fra2, lue1 and ktn1-2, suggesting that irregular development of siliques arised from defects in fertilization (Supplemental Figures 1A–D)
Thorough phenotypic characterization of unpollinated ovule formation in KATANIN 1 mutants compared to Col-0 (Figures 2E–Q) revealed that ovule development was variably defective in KATANIN 1 mutants, ranging from severely malformed to normal and fertile
Summary
Seeds arise from a fertilized ovule and consist of the following parts: the embryo which arises from the zygote, the endosperm which arises from the fertilization of the diploid central cell by haploid sperm cell and the integuments. A major regulatory mechanism of dynamic microtubule turnover in eukaryotes, involves microtubule severing by means of AAA-ATPase family proteins including katanin (McNally and Vale, 1993; Burk et al, 2001), fidgetin (Mukherjee et al, 2012) and spastin (Roll-Mecak and Vale, 2005). In plants as represented by the genetically tractable model Arabidopsis thaliana, only katanin has been identified as a microtubule severing protein (Burk et al, 2001; McClinton et al, 2001), and was shown thereon to play central roles in mechanisms governing microtubule organization. Katanin forms hexameric rings on the surface of microtubules and exerts its catalytic activity using ATP hydrolysis (Hartman and Vale, 1999). In the Arabidopsis genome, only the p60 subunit is expressed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
