NOVELTY - Engineering a plant to increase the production of a biosynthetic product in a desired tissue, comprises introducing an expression cassette into the plant, where the expression cassette comprises a polynucleotide encoding a transcription factor that regulates production of the biosynthetic product operably linked to a heterologous promoter.    USE - The methods are useful for engineering a plant to increase the production of a biosynthetic product in a desired tissue; for engineering a plant having lignin or xylan deposition or xylan O-acetylation that is substantially localized to the vessels of xylem tissue of the plant; for obtaining an increased amount of soluble sugars from a plant in a saccharification reaction; for increasing bioenergy production from biomass derived from a plant; for increasing stem, straw or timber strength from plants during growth; for obtaining a plant having improved resistance to mechanical stress; for obtaining an increased amount of soluble sugars from a plant in a saccharification reaction; and for obtaining an increased C6/C5 sugars ratio from a plant after a hydrolysis reaction (all claimed).    ADVANTAGE - Methods of engineering plants having lignin deposition or xylan deposition that is substantially localized to the vessels of xylem tissue in the plant, and methods of engineering plants to increase production of a desired biosynthetic product, e.g., to have increased secondary cell wall deposition or increased wax/cutin accumulation, are provided. The engineered plants have use in bioenergy production, e.g., by improving the density and the digestibility of biomass derived from the plant and to improve water usage requirements.    DETAILED DESCRIPTION - Engineering a plant to increase the production of a biosynthetic product in a desired tissue, comprises introducing an expression cassette into the plant, where the expression cassette comprises a polynucleotide encoding a transcription factor that regulates production of the biosynthetic product operably linked to a heterologous promoter, where the heterologous promoter is a promoter that induces gene expression of a gene that is a downstream target of the transcription factor in the desired tissue; and culturing the plant under conditions in which the transcription factor is expressed. INDEPENDENT CLAIMS are:    (1) a method of engineering a plant having lignin deposition that is substantially localized to the vessels of xylem tissue of the plant;    (2) a plant engineered by the method above, or a progeny of the plant;    (3) seed from the plant of (2);    (4) a plant cell comprising a polynucleotide encoding a lignin biosynthesis enzyme operably linked to a heterologous vessel-specific promoter;    (5) a plant comprising the plant cell of (4), where the plant has increased secondary wall deposition, and has lignin deposition that is substantially localized to the vessels of xylem tissue of the plant;    (6) biomass comprising plant tissue from the plant or part of the plant of (2);    (7) a method of obtaining an increased amount of soluble sugars from a plant in a saccharification reaction, by subjecting the plant of (2) to a saccharification reaction, thus increasing the amount of soluble sugars that can be obtained from the plant as compared to a wild-type plant;    (8) a plant cell comprising an expression cassette that comprises a polynucleotide encoding a transcription factor that regulates the production of secondary cell wall in woody tissue operably linked to a heterologous promoter, where the promoter is a promoter that induces expression of a gene that is a downstream target of the transcription factor;    (9) a method of increasing bioenergy production from biomass derived from a plant, by harvesting biomass from the plant of (2) or (5); and subjecting the biomass to a conversion reaction, thus increasing bioenergy production as compared to a wild-type plant;    (10) a method of increasing stem, straw or timber strength from plants during growth, by cultivating the plant of (2) or (5) to produce seed, where resistance lodging is improved as compared to a wild type plant;    (11) a method of obtaining a plant having improved resistance to mechanical stress, by cultivating the plant of (2)or (5), thus obtaining a plant having improved resistance to mechanical stress compared to a wild-type plant that has not been genetically modified to increase secondary cell wall production;    (12) a method of engineering a plant having xylan deposition that is substantially localized to the vessels of xylem tissue of the plant;    (13) a plant engineered by the method of (12), or a progeny of the plant;    (14) a plant cell from the plant of (13);    (15) seed from the plant of (13);    (16) a plant cell comprising an expression cassette that comprises a polynucleotide encoding a xylan biosynthesis enzyme operably linked to a heterologous vessel-specific promoter;    (17) a plant comprising the plant cell of (16), where the plant has xylan deposition that is substantially localized to the vessels of xylem tissue of the plant;    (18) biomass comprising plant tissue from the plant or part of the plant of (13) or (17);    (19) a method of obtaining an increased amount of soluble sugars from a plant in a saccharification reaction, by subjecting the plant of (13) or (17) to a saccharification reaction, thus increasing the amount of soluble sugars that can be obtained from the plant as compared to a wild-type plant;    (20) a method of obtaining an increased C6/C5 sugars ratio from a plant after a hydrolysis reaction, by subjecting the plant of (13) or (17) to chemical or enzymatic hydrolysis, thus increasing the amount of C6 sugars compared to CS sugars that can be obtained from the plant as compared to a wild-type plant;    (21) a method of engineering a plant having xylan O-acetylation that is substantially localized to the vessels of xylem tissue of the plant;    (22) a plant engineered by the method of (21), or a progeny of the plant;    (23) a plant cell from the plant of (22);    (24) seed from the plant of (22);    (25) a plant cell comprising an expression cassette that comprises a polynucleotide encoding the xylan O-acetylation enzyme operably linked to a heterologous vessel-specific promoter;    (26) a plant comprising the plant cell of (25), where the plant has xylan O-acetylation that is substantially localized to the vessels of xylem tissue of the plant;    (27) biomass comprising plant tissue from the plant or part of the plant of (22) or (25); and    (28) a method of obtaining an increased amount of soluble sugars from a plant in a saccharification reaction, by subjecting the plant of (22) or (25) to a saccharification reaction, thus increasing the amount of soluble sugars that can be obtained from the plant as compared to a wild-type plant.