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A molecular mechanism that confines the activity pattern of miR165 in A rabidopsis leaf primordia
Author(s) -
Tatematsu Kiyoshi,
Toyokura Koichi,
Miyashima Shunsuke,
Nakajima Keiji,
Okada Kiyotaka
Publication year - 2015
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/tpj.12834
Subject(s) - primordium , epidermis (zoology) , biology , ectopic expression , arabidopsis , microrna , microbiology and biotechnology , psychological repression , mutant , botany , gene , gene expression , genetics , anatomy
Summary In Arabidopsis leaf primordia, the expression of HD ‐Zip III , which promotes tissue differentiation on the adaxial side of the leaf primordia, is repressed by mi RNA 165/166 (miR165/166). Small RNA s, including mi RNA s, can move from cell to cell. In this study, HD ‐Zip III expression was strikingly repressed by miR165/166 in the epidermis and parenchyma cells on the abaxial side of the leaf primordia compared with those on the adaxial side. We also found that the MIR 165A locus, which was expressed in the abaxial epidermis, was sufficient to establish the rigid repression pattern of HD ‐Zip III expression in the leaf primordia. Ectopic expression analyses of MIR 165A showed that the abaxial‐biased miR165 activity in the leaf primordia was formed neither by a polarized distribution of factors affecting miR165 activity nor by a physical boundary inhibiting the cell‐to‐cell movement of mi RNA between the adaxial and abaxial sides. We revealed that cis ‐acting factors, including the promoter, backbone, and mature mi RNA sequence of MIR 165A , are necessary for the abaxial‐biased activity of miR165 in the leaf primordia. We also found that the abaxial‐determining genes YABBY s are trans ‐acting factors that are necessary for the miR165 activity pattern, resulting in the rigid determination of the adaxial–abaxial boundary in leaf primordia. Thus, we proposed a molecular mechanism in which the abaxial‐biased patterning of miR165 activity is confined.

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