NOVELTY - Plant comprising a down-regulated no apical meristem, ATAF and cup-shaped cotyledon (NAC) secondary wall thickening promoting factor (NST) transcription factor, where the plant exhibits reduced lignin content, is new.    USE - The plant (forage plant, biofuel crop, cereal crop, Medicago, switch grass or industrial plant) is useful for: producing a commercial product, which is paper, paper pulp, ethanol, biodiesel, silage, animal feed or fermentable biofuel feedstock; increasing the level or availability of at least one fermentable carbohydrate in a biofuel crop species plant; increasing the digestibility of a forage crop; and increasing the drought tolerance of a plant, where the: forage plant is a forage soybean, alfalfa, clover, Bahia grass, Bermudagrass, dallisgrass, Pangola grass, big bluestem, indiangrass, fescue (Festuca sp.), Dactylis sp., Brachypodium distachyon, smooth bromegrass, orchard grass, Kentucky bluegrass or reed canary grass; biofuel crop is switchgrass (Panicum virgatum), giant reed (Arundo donax), reed canary grass (Phalaris arundinacea), Miscanthus x giganteus, Miscanthus sp., Lespedeza cuneata, corn, sugarcane, Sorghum, millet, ryegrass (Lolium multiflorum), timothy, Kochia (Kochia scoparia), forage soybeans, alfalfa, clover, sunn hemp, kenaf, Bahia grass, Bermuda grass, dallisgrass, Pangola grass, big bluestem, indiangrass, fescue (Festuca sp.), Dactylis sp., Brachypodium distachyon, smooth bromegrass, orchardgrass, Kentucky bluegrass or poplar; and the cereal crop is maize, rice, wheat, barley, Sorghum, millet, oat, rye, triticle, buckwheat, fonio or quinoa (all claimed). Test details are described but no results given.    ADVANTAGE - The plant comprising down-regulated NST transcription factor exhibits improved digestibility and higher leaf to stem ratio than wild-type plants.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) a plant part of the plant;    (2) a nucleic acid molecule comprising a nucleic acid sequence, which is (a) a nucleic acid sequence that hybridizes to the nucleic acid sequence complementary to the sequence of SEQ ID NO: 1-4 or 5 or their fragments under conditions of 1x standard sodium citrate (SSC) and 65 degrees C, (b) a nucleic acid comprising the sequence of SEQ ID NO: 1-4 or 5, (c) a nucleic acid sequence exhibiting at least 80% sequence identity to the nucleic acid sequence of SEQ ID NO: 1-4 or 5 and (d) a nucleic acid sequence comprising a complement of (a)-(c), where the nucleic acid sequence is operably linked to a heterologous promoter sequence and expression of the nucleic acid molecule in a plant cell modulates the lignin content of the plant cell;    (3) a transgenic plant cell comprising the nucleic acid molecule;    (4) a transgenic plant or its part comprising the nucleic acid molecule;    (5) a biofuel feedstock comprising the nucleic acid molecule;    (6) a method of increasing the level or availability of at least one fermentable carbohydrate in a biofuel crop species plant, or decreasing the lignin content in a plant, or increasing the digestibility of a forage crop, or increasing the drought tolerance of a plant, comprising down-regulating an NST transcription factor in the plant; and    (7) a method of increasing the lignin content of a plant comprising expressing the DNA molecule in the plant.