Transgenic plants with enhanced growth characteristics

Abstract

The invention relates to transgenic plants exhibiting dramatically enhanced growth rates, greater seed and fruit/pod yields, earlier and more productive flowering, more efficient nitrogen utilization, increased tolerance to high salt conditions, and increased biomass yields. In one embodiment, transgenic plants engineered to over-express both glutamine phenylpyruvate transaminase (GPT) and glutamine synthetase (GS) are provided. The GPT+GS double-transgenic plants of the invention consistently exhibit enhanced growth characteristics, with T0 generation lines showing an increase in biomass over wild type counterparts of between 50% and 300%. Generations that result from sexual crosses and/or selfing typically perform even better, with some of the double-transgenic plants achieving an astounding four-fold biomass increase over wild type plants.

1 . A transgenic plant comprising a GPT transgene and a GS transgene, wherein each of said GPT transgene and said GS transgene is operably linked to a plant promoter. 
     
     
         2 . (canceled) 
     
     
         3 . The transgenic plant of  claim 1 , wherein each plant promoter is heterologous to the plant. 
     
     
         4 . The transgenic plant of  claim 1 , wherein the plant promoter operably linked to the GPT transgene is heterologous to the species from which the GPT transgene is derived, and wherein the plant promoter operably linked to the GS transgene is heterologous to the species from which the GS transgene is derived. 
     
     
         5 . The transgenic plant of  claim 4 , wherein the GPT transgene encodes a polypeptide having an amino acid sequence selected from the group consisting of (a) SEQ ID NO: 2; SEQ ID NO: 9; SEQ ID NO: 15, SEQ ID NO: 19, SEQ ID NO: 21, SEQ ID NO 24, SEQ ID NO: 30, SEQ ID NO: 31, SEQ ID NO: 32, SEQ ID NO: 33, SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO: 46 and SEQ ID NO: 49, and (b) an amino acid sequence that is at least 75% identical to any one of SEQ ID NO: 2; SEQ ID NO: 9; SEQ ID NO: 15, SEQ ID NO: 19, SEQ ID NO: 21, SEQ ID NO 24, SEQ ID NO: 30, SEQ ID NO: 31, SEQ ID NO: 32, SEQ ID NO: 33, SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO: 46 and SEQ ID NO: 49 and has GPT activity. 
     
     
         6 . The transgenic plant of  claim 4 , wherein the GS transgene encodes a polypeptide having an amino acid sequence selected form the group consisting of (a) SEQ ID NO: 4, SEQ ID NO: 7 from residue 11, and SEQ ID NO: 41, and (b) an amino acid sequence that is at least 75% identical to SEQ ID NO: 4, SEQ ID NO: 7 or SEQ ID NO: 41. 
     
     
         7 . The transgenic plant according to  claim 1 , wherein the GPT and GS transgenes are incorporated into the genome of the plant. 
     
     
         8 . The transgenic plant according to  claim 1 , wherein the GPT and/or the GS transgenes are incorporated into the plastome of the plant. 
     
     
         9 - 15 . (canceled) 
     
     
         16 . The transgenic plant according to  claim 1 , which is a plant of the phylum  Tracheophyta.    
     
     
         17 . The transgenic plant of  claim 16 , wherein the transgenic plant is selected from the group consisting of fruits including apples, avocado, banana, blackberry, blueberry, cherries, cranberries, cantaloupes, grapefruit, lemons, limes, nectarines, oranges, peaches, pineapples, pears, plums, tangelos, tangerines, papaya, mango, strawberry, raspberry, grape, kiwi fruit, olives, and coconuts; vegetables including brussel sprouts, radish, mung beans, carrots, sugarbeet, yams, horseradish, flax, sesame, turnip, sweet potato, cabbage, canola, cucumbers, eggplant, lettuce, onion, okra, parsnips, pumpkins and spinach; flowering plants including lily, carnation, chrysanthemum, petunia, geranium, violet, gladioli, orchid, and lilac; trees including oil palm; ornamental plants; canola; lupins; and cotton. 
     
     
         18 . The transgenic plant of  claim 16 , wherein the transgenic plant is selected from the group consisting of plants of the families Poaceae,  Gossypium , Fabaceae, Brassicaceae, Rutaceae, Rubiaceae, Cucurbitaceae, Rosaceae, Asteraceae, Amaranthaceae and Brassicaceae. 
     
     
         19 . The transgenic plant of  claim 16 , wherein the transgenic plant is selected from the group consisting of plants of the genera  Avena, Hordeum, Oryza, Panicum, Phleum, Saccharum, Secale, Sorghum, Triticum, Zea, Pennisetum, Lycopersicon, Capiscum, Fagopyrum, Triticosecale, Chenopodium, Digitaria, Manihot, Ipomoea, Olea, Daucus, Pastinaca, Raphanus, Dioscorea, Armoracia, Elaeis, Linum, Carthamus, Sesamum, Vitis , and  Solanum.    
     
     
         20 - 22 . (canceled) 
     
     
         23 . A method of producing a plant having increased nitrogen use efficiency relative to an analogous wild type or untransformed plant, comprising:
 (a) introducing a GPT transgene into the plant;   (b) introducing a GS transgene into the plant or a progeny of the plant;   (c) expressing the GPT transgene and the GS transgene in the plant or the progeny of the plant; and,   (d) selecting a plant having an increased nitrogen use efficiency relative to a plant of the same species that does not comprise a GPT transgene or a GS transgene.   
     
     
         24 - 29 . (canceled) 
     
     
         30 . A transplastomic plant or cell line carrying a GPT transgene and a GS transgene expression cassette, wherein said expression cassette is flanked by sequences from the plant or plant cell's plastome. 
     
     
         31 - 35 . (canceled)