Microtubule-associated protein AtMPB2C plays a role in organization of cortical microtubules, stomata patterning, and tobamovirus infectivity.
AtMPB2C is the Arabidopsis (Arabidopsis thaliana) homolog of MPB2C, a microtubule-associated host factor of tobacco mosaic virus movement protein that was been previously identified in Nicotiana tabacum. To analyze the endogenous function of AtMPB2C and its role in viral infections, transgenic Arabidopsis plant lines stably overexpressing green fluorescent protein (GFP)-AtMPB2C were established. The GFP-AtMPB2C fusion protein was detectable in various cell types and organs and localized at microtubules in a punctuate pattern or in filaments. To determine whether overexpression impacted on the cortical microtubular cytoskeleton, GFP-AtMPB2C-overexpressing plants were compared to known microtubular marker lines. In rapidly elongated cell types such as vein cells and root cells, GFP-AtMPB2C overexpression caused highly unordered assemblies of cortical microtubules, a disturbed, snake-like microtubular shape, and star-like crossing points of microtubules. Phenotypically, GFP-AtMPB2C transgenic plants showed retarded growth but were viable and fertile. Seedlings of GFP-AtMPB2C transgenic plants were characterized by clockwise twisted leaves, clustered stomata, and enhanced drought tolerance. GFP-AtMPB2C-overexpressing plants showed increased resistance against oilseed rape mosaic virus, a close relative of tobacco mosaic virus, but not against cucumber mosaic virus when compared to Arabidopsis wild-type plants. These results suggest that AtMPB2C is involved in the alignment of cortical microtubules, the patterning of stomata, and restricting tobamoviral infections.
Ruggenthaler
Pia
P
Department of Medical Biochemistry, Medical University of Vienna, 1030 Vienna, Austria.
Fichtenbauer
Daniela
D
Krasensky
Julia
J
Jonak
Claudia
C
Waigmann
Elisabeth
E
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000378:metabolism* / Q000821:virology*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000378:metabolism*; D055864:Droughts; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism* / Q000821:virology; D008969:Molecular Sequence Data; D010936:Plant Extracts / Q000378:metabolism; D054046:Plant Stomata / Q000166:cytology / Q000378:metabolism* / Q000821:virology*; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017898:Tobamovirus / Q000472:pathogenicity*
D029681:Arabidopsis Proteins; C540501:MPB2C protein, Arabidopsis; D008869:Microtubule-Associated Proteins; D010936:Plant Extracts; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins