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Overexpression of tomato LeAGP‐1 arabinogalactan‐protein promotes lateral branching and hampers reproductive development
Author(s) -
Sun Wenxian,
Kieliszewski Marcia J.,
Showalter Allan M.
Publication year - 2004
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2004.02274.x
Subject(s) - green fluorescent protein , biology , transgene , messenger rna , genetically modified crops , agrobacterium , microbiology and biotechnology , transformation (genetics) , genetically modified tomato , lycopersicon , cytokinin , arabinogalactan , phenotype , auxin , botany , gene , biochemistry , cell wall
Summary 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.