title: Arabidopsis VILLIN2 and VILLIN3 act redundantly in sclerenchyma development via bundling of actin filaments.
abstract: The organization of the actin cytoskeleton has been implicated in sclerenchyma development. However, the molecular mechanisms linking the actin cytoskeleton to this process remain poorly understood. In particular, there have been no studies showing that direct genetic manipulation of the actin cytoskeleton affects sclerenchyma development. Villins belong to the villin/gelsolin/fragmin superfamily and are versatile actin-modifying proteins. Several recent studies have implicated villins in tip growth of single cells, but how villins act in multicellular plant development remains largely unknown. Here, we found that two closely related villin isovariants from Arabidopsis, VLN2 and VLN3, act redundantly in sclerenchyma development. Detailed analysis of cross-sections from inflorescence stems of vln2 vln3 double mutant plants revealed a reduction in stem size and in the number of vascular bundles; however, no defects in synthesis of the secondary cell wall were detected. Surprisingly, the vln2 vln3 double mutation did not affect cell elongation of inter-fascicular fibers. Biochemical analyses showed that recombinant VLN2 was able to cap, sever and bundle actin filaments, similar to VLN3. Consistent with these biochemical activities, loss of function of VLN2 and VLN3 resulted in a decrease in the amount of F-actin and actin bundles in plant cells. Collectively, our findings demonstrate that VLN2 and VLN3 act redundantly in sclerenchyma development via bundling of actin filaments.
authors.affiliation: Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Chanchan
authors.initials: C
authors.lastname: Bao
authors.forename: Juan
authors.initials: J
authors.lastname: Wang
authors.forename: Ruihui
authors.initials: R
authors.lastname: Zhang
authors.forename: Baocai
authors.initials: B
authors.lastname: Zhang
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.forename: Yihua
authors.initials: Y
authors.lastname: Zhou
authors.forename: Shanjin
authors.initials: S
authors.lastname: Huang
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism; D056626:Inflorescence / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D016254:Mutagenesis, Insertional; D010641:Phenotype; D018547:Plant Stems / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D058526:Plant Vascular Bundle / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D011994:Recombinant Proteins
chemical_list: D000199:Actins; D029681:Arabidopsis Proteins; D008840:Microfilament Proteins; D011994:Recombinant Proteins; C000591219:VLN3 protein, Arabidopsis; C585920:villin 2 protein, Arabidopsis