OPEN ACCESS ARTICLE

This Article Free via Open Access: OA OA Full Text Full Text (PDF) Supplemental Data OA All Versions of this Article: 145/1/277    most recent pp.107.102095v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Kwak, M. S. Articles by Bae, J. M. Search for Related Content PubMed PubMed Citation Articles by Kwak, M. S. Articles by Bae, J. M. Agricola Articles by Kwak, M. S. Articles by Bae, J. M.

SYSTEMS BIOLOGY, MOLECULAR BIOLOGY, AND GENE REGULATION

A Sepal-Expressed ADP-Glucose Pyrophosphorylase Gene (NtAGP) Is Required for Petal Expansion Growth in ‘Xanthi’ Tobacco^{1,[C],[W],[OA]}

School of Life Sciences and Biotechnology, Korea University, Seoul 136–701, Korea (M.S.K., K.-H.P., J.S.S., J.M.B.); Plant Genome Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305–806, Korea (S.R.M., J.R.L.); Biosafety Division, National Institute of Agricultural Biotechnology, Rural Developmental Administration, Suwon 441–707, Korea (S.-M.L.); and Department of Molecular Biology, Sejong University, Seoul 136–747, Korea (K.-N.K.)

In this study, a tobacco (Nicotiana tabacum ‘Xanthi’) ADP-glucose pyrophosphorylase cDNA (NtAGP) was isolated from a flower bud cDNA library and the role of NtAGP in the growth of the floral organ was characterized. The expression of NtAGP was high in the sepal, moderate in the carpel and stamen, and low in the petal tissues. NtAGP-antisense plants produced flowers with abnormal petal limbs due to the early termination of the expansion growth of the petal limbs between the corolla lobes. Microscopic observation of the limb region revealed that cell expansion was limited in NtAGP-antisense plants but that cell numbers remained unchanged. mRNA levels of NtAGP, ADP-glucose pyrophosphorylase activity, and starch content in the sepal tissues of NtAGP-antisense plants were reduced, resulting in significantly lower levels of sugars (sucrose, glucose, and fructose) in the petal limbs. The feeding of these sugars to flower buds of the NtAGP-antisense plants restored the expansion growth in the limb area between the corolla lobes. Expansion growth of the petal limb between the corolla lobes was severely arrested in ‘Xanthi’ flowers from which sepals were removed, indicating that sepal carbohydrates are essential for petal limb expansion growth. These results demonstrate that NtAGP plays a crucial role in the morphogenesis of petal limbs in ‘Xanthi’ through the synthesis of starch, which is the main carbohydrate source for expansion growth of petal limbs, in sepal tissues.

² These authors contributed equally to the article.

The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Jung Myung Bae (jmbae{at}korea.ac.kr).

^[C] Some figures in this article are displayed in color online but in black and white in the print edition.

^[W] The online version of this article contains Web-only data.

^[OA] Open Access articles can be viewed online without a subscription.

www.plantphysiol.org/cgi/doi/10.1104/pp.107.102095

^* Corresponding author; e-mail jmbae{at}korea.ac.kr.

Received May 9, 2007; accepted July 16, 2007; published July 27, 2007.