Submitted to: Plant Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2008
Publication Date: 7/2/2008
Publication URL: http://www3.interscience.wiley.com/cgi-bin/fulltext/120776988/PDFSTART
Citation: Jasinski, S., Tattersall, A., Piazza, P., Hay, A., Martinez-Garcia, J.F., Schmitz, G., Theres, K., McCormick, S.M., Tsiantis, M. 2008. PROCERA encodes a DELLA protein that mediates control of dissected leaf form in tomato. Plant Journal. "Postprint"; doi: 10.1111/j.1365-313X.2008.03628.x Interpretive Summary: A tomato mutant called procera has simple leaves with smooth margins, unlike normal tomato leaves. Normal tomato plants treated with the hormone Gibberellin (GA) have leaves like procera. We show that the PROCERA gene encodes a protein that represses growth, and that this repression can be reversed by GA treatment.
Technical Abstract: Leaves of seed plants can be described as simple, where the leaf blade is entire, or dissected, where the blade is divided into distinct leaflets. Mechanisms that define leaflet number and position are poorly understood and their elucidation presents an attractive opportunity to understand mechanisms controlling organ shape in plants. In tomato, a plant with dissected leaves, KNOTTED1-like homeodomain proteins (KNOX) are positive regulators of leaflet formation. Conversely, the hormone Gibberellin (GA) can antagonise the effects of KNOX overexpression and reduce leaflet number, suggesting that GA may be a negative regulator of leaflet formation. However, when and how GA acts on leaf development is unknown. The reduced leaflet number phenotype of the tomato mutant procera (pro) mimics that of plants to which GA has been applied during leaf development, suggesting that PRO may define a GA signalling component required to promote leaflet formation. Here we show that PRO encodes a DELLA-type growth repressor that likely mediates GA-reversible growth restraint. We demonstrate that PRO is required to promote leaflet initiation at early stages of leaf primordia growth and conversely that reduced GA biosynthesis increases the capability of the tomato leaf to produce leaflets in response to elevated KNOX activity. We propose that in tomato, DELLA activity regulates leaflet number by defining the correct timing for leaflet initiation.