Conserved genetic determinant of motor organ identity in Medicago truncatula and related legumes
- Jianghua Chena,
- Carol Moreaub,
- Yu Liua,
- Masayoshi Kawaguchic,
- Julie Hoferb,d,
- Noel Ellisb,d, and
- Rujin Chena,1
- aPlant Biology Division, Samuel Roberts Noble Foundation, Ardmore, OK 73401;
- bDepartment of Crop Genetics, The John Innes Centre, Colney, Norwich NR4 7UH, United Kingdom;
- cDivision of Symbiotic Systems, National Institute for Basic Biology, Myodaiji-cho, Okazaki 444-8585, Japan; and
- dInstitute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, Ceredigion SY23 3EE, United Kingdom
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Edited by Sarah Hake, University of California, Berkeley, CA, and approved May 11, 2012 (received for review March 16, 2012)
Abstract
Plants exhibit various kinds of movements that have fascinated scientists and the public for centuries. Physiological studies in plants with the so-called motor organ or pulvinus suggest that cells at opposite sides of the pulvinus mediate leaf or leaflet movements by swelling and shrinking. How motor organ identity is determined is unknown. Using a genetic approach, we isolated a mutant designated elongated petiolule1 (elp1) from Medicago truncatula that fails to fold its leaflets in the dark due to loss of motor organs. Map-based cloning indicated that ELP1 encodes a putative plant-specific LOB domain transcription factor. RNA in situ analysis revealed that ELP1 is expressed in primordial cells that give rise to the motor organ. Ectopic expression of ELP1 resulted in dwarf plants with petioles and rachises reduced in length, and the epidermal cells gained characteristics of motor organ epidermal cells. By identifying ELP1 orthologs from other legume species, namely pea (Pisum sativum) and Lotus japonicus, we show that this motor organ identity is regulated by a conserved molecular mechanism.
Footnotes
- ↵1To whom correspondence should be addressed. E-mail: rchen{at}noble.org.
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Author contributions: J.C., C.M., N.E., and R.C. designed research; J.C., C.M., and Y.L. performed research; M.K. contributed new reagents/analytic tools; J.C., C.M., J.H., N.E., and R.C. analyzed data; and J.C. and R.C. wrote the paper.
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The authors declare no conflict of interest.
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This article is a PNAS Direct Submission.
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Data deposition: The sequences reported in this paper have been deposited in the GenBank database [accession nos. JQ653161 (ELP1), JQ653162 (SLP), JQ653163 (Apu), JQ653164 (Glyma06g18860), and JQ653165 (Glyma04g36080)].
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See Commentary on page 11474.
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This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1204566109/-/DCSupplemental.
