Plant Molecular Biology

, Volume 61, Issue 4–5, pp 781–793 | Cite as

Floral patterning defects induced by Arabidopsis APETALA2 and microRNA172 expression in Nicotiana benthamiana

  • Sizolwenkosi Mlotshwa
  • Zhiyong Yang
  • YunJu Kim
  • Xuemei Chen
Article

Abstract

Floral patterning and morphogenesis are controlled by many transcription factors including floral homeotic proteins, by which floral organ identity is determined. Recent studies have uncovered widespread regulation of transcription factors by microRNAs (miRNAs), ~21-nucleotide non-coding RNAs that regulate protein-coding RNAs through transcript cleavage and/or translational inhibition. The regulation of the floral homeotic gene APETALA2 (AP2) by miR172 is crucial for normal Arabidopsis flower development and is likely to be conserved across plant species. Here we probe the activity of the AP2/miR172 regulatory circuit in a heterologous Solanaceae species, Nicotiana benthamiana. We generated transgenic N. benthamiana lines expressing Arabidopsis wild type AP2 (35S::AP2), miR172-resistant AP2 mutant (35S::AP2m3) and MIR172a-1 (35S::MIR172) under the control of the cauliflower mosaic virus 35S promoter. 35S::AP2m3 plants accumulated high levels of AP2 mRNA and protein and exhibited floral patterning defects that included proliferation of numerous petals, stamens and carpels indicating loss of floral determinacy. On the other hand, nearly all 35S::AP2 plants accumulated barely detectable levels of AP2 mRNA or protein and were essentially non-phenotypic. Overall, the data indicated that expression of the wild type Arabidopsis AP2 transgene was repressed at the mRNA level by an endogenous N. benthamiana miR172 homologue that could be detected using Arabidopsis miR172 probe. Interestingly, 35S::MIR172 plants had sepal-to-petal transformations and/or more sepals and petals, suggesting interference with N. benthamiana normal floral homeotic gene function in perianth organs. Our studies uncover the potential utility of the Arabidopsis AP2/miR172 system as a tool for manipulation of floral architecture and flowering time in non-model plants.

Keywords

APETALA2 Arabidopsis microRNA miR172 Nicotiana benthamiana 

Abbreviations

AG

AGAMOUS

AP2

APETALA2

CaMV

cauliflower mosaic virus

DEF

DEFICIENS

GLO

GLOBOSA

HMW RNA

high molecular weight RNA

LMW RNA

low molecular weight RNA

miRNA

microRNA

miR172

microRNA172

NAG1

Nicotiana tabacum AGAMOUS

NbAG

Nicotiana benthamiana AGAMOUS

NbAP2

Nicotiana benthamiana APETALA2

NbDEF

Nicotiana benthamiana DEFICIENS

NbGLO

Nicotiana benthamiana GLOBOSA

NbWUS

Nicotiana benthamiana WUSCHEL

RUBISCO

ribulose bisphosphate carboxylase

TOE

TARGET OF EAT

WUS

WUSCHEL

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Copyright information

© Springer Science+Business Media B.V. 2006

Authors and Affiliations

  • Sizolwenkosi Mlotshwa
    • 1
  • Zhiyong Yang
    • 1
  • YunJu Kim
    • 1
  • Xuemei Chen
    • 1
  1. 1.Department of Botany & Plant SciencesUniversity of CaliforniaCalifornia, RiversideUSA

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