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Arabidopsis SMALL AUXIN UP RNA63 promotes hypocotyl and stamen filament elongation
Author(s) -
Chae Keun,
Isaacs Cameron G.,
Reeves Paul H.,
Maloney Gregory S.,
Muday Gloria K.,
Nagpal Punita,
Reed Jason W.
Publication year - 2012
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2012.05024.x
Subject(s) - auxin , hypocotyl , arabidopsis , biology , microbiology and biotechnology , petal , arabidopsis thaliana , green fluorescent protein , stamen , botany , polar auxin transport , gene , biochemistry , mutant , pollen
Summary Auxin regulates plant growth and development in part by activating gene expression. Arabidopsis thaliana SMALL AUXIN UP RNA s ( SAUR s) are a family of early auxin‐responsive genes with unknown functionality. Here, we show that transgenic plant lines expressing artificial microRNA constructs ( aMIR‐SAUR‐A or ‐ B ) that target a SAUR subfamily ( SAUR61–SAUR68 and SAUR75 ) had slightly reduced hypocotyl and stamen filament elongation. In contrast, transgenic plants expressing SAUR63:GFP or SAUR63:GUS fusions had long hypocotyls, petals and stamen filaments, suggesting that these protein fusions caused a gain of function. SAUR63:GFP and SAUR63:GUS seedlings also accumulated a higher level of basipetally transported auxin in the hypocotyl than did wild‐type seedlings, and had wavy hypocotyls and twisted inflorescence stems. Mutations in auxin efflux carriers could partially suppress some SAUR63:GUS phenotypes. In contrast, SAUR63:HA plants had wild‐type elongation and auxin transport. SAUR63:GFP protein had a longer half‐life than SAUR63:HA. Fluorescence imaging and microsomal fractionation studies revealed that SAUR63:GFP was localized mainly in the plasma membrane, whereas SAUR63:HA was present in both soluble and membrane fractions. Low light conditions increased SAUR63:HA protein turnover rate. These results indicate that membrane‐associated Arabidopsis SAUR63 promotes auxin‐stimulated organ elongation.