NOVELTY - Isolated polypeptide having expansin activity comprising: polypeptide comprising amino acid sequence having at least 60% sequence identity to polypeptide of SEQ ID NO: 2; polypeptide encoded by polynucleotide that hybridizes under at least medium stringency conditions with polypeptide coding sequence of SEQ ID NO: 1; polypeptide encoded by polynucleotide comprising nucleotide sequence having at least 60% sequence identity to polypeptide coding sequence of SEQ ID NO: 1; or variant comprising substitution, deletion and/or insertion of amino acid of polypeptide of SEQ ID NO: 2, is new.    USE - The polypeptide is useful for degrading or converting a cellulosic material, which is useful in producing fermentation products (all claimed) e.g. alcohol (e.g. arabinitol, butanol, ethanol, glycerol, methanol, 1,3-propanediol, sorbitol and xylitol), organic acid (e.g. acetic acid, acetonic acid, adipic acid, ascorbic acid, citric acid, 2,5-diketo-D-gluconic acid, formic acid, fumaric acid, glucaric acid, gluconic acid, glucuronic acid, glutaric acid, 3-hydroxypropionic acid, itaconic acid, lactic acid, malic acid, malonic acid, oxalic acid, oxaloacetic acid, propionic acid, succinic acid and xylonic acid), ketone (e.g. acetone), amino acid (e.g. aspartic acid, glutamic acid, glycine, lysine, serine and threonine), gas (e.g. methane, hydrogen, carbon dioxide and carbon monoxide) and protein as a high value product.    ADVANTAGE - The polypeptide improves the quality of a food or feed, e.g. improves nutritional value, palatability and rheological properties, or destroys an anti-nutritive factor.    DETAILED DESCRIPTION - Isolated polypeptide having expansin activity comprising: a polypeptide comprising an amino acid sequence having at least 60% sequence identity to the mature polypeptide comprising amino acid sequence comprising a fully defined 269 amino acid residues of SEQ ID NO: 2, as given in the specification; a polypeptide encoded by a polynucleotide that hybridizes under at least medium stringency conditions with the mature polypeptide coding sequence comprising nucleotide sequence comprising a fully defined 807 bps of SEQ ID NO: 1, as given in the specification, or the genomic DNA sequence comprising the mature polypeptide coding sequence of SEQ ID NO: 1, or its full-length complementary strand; a polypeptide encoded by a polynucleotide comprising a nucleotide sequence having at least 60% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 1; or a variant comprising a substitution, deletion, and/or insertion of at least one amino acid of the mature polypeptide of SEQ ID NO: 2, is new. INDEPENDENT CLAIMS are also included for:    (1) an isolated polynucleotide (I) comprising a nucleotide sequence that encodes the polypeptide;    (2) productions of the polypeptide;    (3) a method of producing a mutant of a parent cell, comprising disrupting or deleting a polynucleotide encoding the polypeptide or its portion, which results in the mutant producing less of the polypeptide than the parent cell;    (4) a transgenic plant, or its part, or its cell transformed with a polynucleotide encoding the polypeptide;    (5) a double-stranded inhibitory RNA (dsRNA) molecule comprising a subsequence of the polynucleotide, where optionally the dsRNA is a small interfering RNA (siRNA) or a microRNA (miRNA) molecule;    (6) a method of inhibiting the expression of a polypeptide having expansin activity in a cell, comprising: administering the dsRNA molecule to the cell; or expressing the dsRNA molecule in the cell;    (7) an isolated polynucleotide (II) encoding a signal peptide comprising amino acid residues 1-17 of SEQ ID NO: 2;    (8) a method of producing a protein, comprising: cultivating a recombinant host cell comprising a gene encoding a protein operably linked to the polynucleotide (II), where the gene is foreign to the polynucleotide encoding the signal peptide, under conditions conducive for production of the protein; and recovering the protein;    (9) a method for degrading or converting a cellulosic material, comprising: treating the cellulosic material with an enzyme composition in the presence of the polypeptide; and    (10) a method for producing a fermentation product, comprising: saccharifying a cellulosic material with an enzyme composition in the presence of the polypeptide; fermenting the saccharified cellulosic material with at least one fermenting microorganisms to produce the fermentation product; and recovering the fermentation product from the fermentation.