Overexpression of tomato LeAGP-1 arabinogalactan-protein promotes lateral branching and hampers reproductive development
Article first published online: 6 DEC 2004
The Plant Journal
Volume 40, Issue 6, pages 870–881, December 2004
How to Cite
Sun, W., Kieliszewski, M. J. and Showalter, A. M. (2004), Overexpression of tomato LeAGP-1 arabinogalactan-protein promotes lateral branching and hampers reproductive development. The Plant Journal, 40: 870–881. doi: 10.1111/j.1365-313X.2004.02274.x
- Issue published online: 6 DEC 2004
- Article first published online: 6 DEC 2004
- Received 12 June 2004; revised 22 August 2004; accepted 3 September 2004.
- LeAGP-1 arabinogalactan-protein;
LeAGP-1 is a glycosylphosphatidylinositol (GPI)-anchored arabinogalactan-protein (AGP) in tomato (Lycopersicon esculentum). Patterns of mRNA expression and protein localization for LeAGP-1 indicate that it likely functions in certain aspects of plant growth and development. To elucidate LeAGP-1 function(s), transgenic tomato plants expressing enhanced green fluorescent protein (GFP) fused to LeAGP-1 [GFP-LeAGP-1] or two LeAGP-1 variants, one lacking the C-terminal GPI-anchor domain [GFP-LeAGP-1ΔC] and the other lacking the lysine-rich domain [GFP-LeAGP-1ΔK], under the control of the CaMV35S promoter were produced using Agrobacterium-mediated transformation. Transgenic T0 and T1 lines with high levels of both GFP-LeAGP-1 mRNA and protein: (i) were significantly shorter; (ii) were highly branched; (iii) produced more flower buds, but most of these flowers did not mature, resulting in less fruit production; and (iv) produced seeds that were significantly smaller than normal seeds. Overexpression of LeAGP-1ΔK had a similar or even more pronounced effect on plant vegetative and reproductive growth, while the effect of LeAGP-1ΔC overexpression on plant reproduction was minimal. These results indicate that the GPI anchor is critical for LeAGP-1 function. As the phenotype of GFP-LeAGP-1 overexpressing transgenic plants is similar to that of cytokinin-overproducing plants, mRNA expression patterns of LeAGP-1 under different hormone treatments were examined. Cytokinins upregulated LeAGP-1 mRNA expression, while auxins and ABA inhibited LeAGP-1 mRNA expression. Based on these results, GPI-anchored LeAGP-1 most likely functions in plant growth and development in concert with auxin/cytokinin signaling.