Growth and Vegetative Development
Vvedenskaya, Irina , Kerstetter, Randall A. .
A novel pathway links chloroplast function and adaxial-abaxial leaf polarity in Arabidopsis.
Leaves of flowering plants develop with a distinct adaxial-abaxial asymmetry that reflects functional specializations for intercepting light energy and exchanging gases. Microsurgical and molecular genetic studies have demonstrated that the proper specification of adaxial-abaxial polarity requires communication between the SAM and the incipient leaf, and that subsequent blade outgrowth is dependent on the juxtaposition of adaxial and abaxial fates. Adaxial-abaxial asymmetry in lateral organs depends on mutually repressive interactions between members of several families of transcription factors and on posttranscriptional regulation by small regulatory RNAs (reviewed by Kidner, 2007).
We have recently characterized a new regulator of leaf polarity, FLAVODENTATA (FLV), which reveals a previously unidentified relationship between chloroplast function and adaxial-abaxial polarity during leaf development. The flv mutant shows light intensity-dependent defects in greening and leaf morphogenesis. Young leaves on flv plants are serrated, white to pale green, and occasionally form radially symmetric, needle-shaped leaves. The reduced greening observed in flv suggests defects in chloroplast function whereas needle-shaped leaves indicate defects in the proper specification of adaxial leaf fate. We found that the FLV encodes a pentatricopeptide repeat (PPR) protein with a predicted chloroplast signal sequence. Members of the PPR family have been shown to be sequence-specific RNA-binding proteins that mediate a variety of RNA processing events. Here we show that strong synergistic interactions between flv and mutations in genes involved in the regulation of adaxial-abaxial polarity indicate that FLV may act in an independent genetic pathway to specify normal leaf morphogenesis.
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1 - Waksman Institute of Microbiology, Rutgers University, 190 Frelinghuysen Road, Piscataway, NJ, 08854, USA
2 - Waksman Institute of Microbiology, Rutgers University
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM