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Title: Expression of a Phenylcoumaran Benzylic Ether Reductase - Like Protein in the Ovules of Gossypium hirsutum

item Turley, Rickie

Submitted to: Biologia Plantarum
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2007
Publication Date: 11/9/2008
Citation: Turley, R.B. 2008. Expression of a Phenylcoumaran Benzylic Ether Reductase - Like Protein in the Ovules of Gossypium hirsutum. Biologia Plantarum. 52:759-762.

Interpretive Summary: In the search for proteins which may improve cotton yields by increasing fibers on the ovule, we have examined proteins which are produced in cotton lines which produce fiber and not produced in cotton mutants which do not produce fiber. The reason for using mutants without fiber is that they are identical to the fiber producing ovules in everything except fiber production. Once a difference is found between the fiber producing line and the mutant, it has a better chance of being important. Comparisons were made during early ovule growth before, during, and after fibers begin to grow (initiation). We describe and partially characterize one protein which was found in the cotton line producing fiber and not in the mutant fiberless line. There is evidence this protein is expressed in all cotton organs and tissues including the leaf, stem, roots, seedlings and fiber. The protein has been suggested to be involved in lignin (a compound which give plants strength to stand upright) production. This would explain the presence of this protein throughout the plant except for the fiber which does not produces lignin. The partial characterization of this protein indicates that it is not important in improving cotton yields.

Technical Abstract: A unique protein was discovered in the 2 D PAGE profiles of a wild-type cotton line. This protein was not present in the fiberless SL 1-7-1 cotton line. The protein was purified from 2-D PAGE of 4 days post anthesis ovules and partially sequenced. The short amino acid sequence was nearly identical to the deduced amino acid sequences for cotton phenylcoumaran benzylic ether reductase (PCBER) protein. A consensus sequence was assembled from ESTs encoding PCBER genes, primers were designed, and a full length gene was amplified from plasmid DNA from a 72 h etiolated cotton cotyledon library. The PCR reaction generated a 950 bp product with unique EcoRI (5') and (3') KpnI restriction sites for directional insertion in frame with the alpha-factor secretion sequence in the expression vector pPICZ alpha A. Nucleotide sequencing was performed, and the full length coding region was 924 bp encoding a protein of 308 amino acids. Comparisons of the molecular mass and pIs were similar between the measured protein (2D PAGE) and the theoretical deduced protein. A heterologous protein of cotton PCBER was expressed in Pichia pastoris and partially characterized. It is postulated that PCBER has a role in fiber growth but not in fiber initiation.