Increasing inositol (1,4,5)-trisphosphate metabolism affects drought tolerance, carbohydrate metabolism and phosphate-sensitive biomass increases in tomato.
Inositol-(1,4,5)-trisphosphate (InsP(3)) is a second messenger in plants that increases in response to many stimuli. The metabolic consequences of this signalling pathway are not known. We reduced the basal level of InsP(3) in tomato (Solanum lycopersicum cv. Micro-Tom) by expressing the human type I inositol polyphosphate 5-phosphatase (InsP 5-ptase) gene. Transgenic lines producing InsP 5-ptase protein had between 15% and 30% of the basal InsP(3) level of control plants. This increased hydrolysis of InsP(3) caused dramatic increases in drought tolerance, vegetative biomass and lycopene and hexose concentrations in the fruits. Transcript profiling of root, leaf and fruit tissues identified a small group of genes, including a cell-wall invertase inhibitor gene, that were differentially regulated in all tissues of the InsP 5-ptase expressing plants. Significant differences were found in the amounts of carbohydrates and organic phosphate in these plants. Plants with increased hydrolysis of InsP(3) in the cytosol also showed increased net CO(2)-fixation and sucrose export into sink tissue and storage of hexoses in the source leaves. The increase in biomass was dependent on the supply of inorganic phosphate in the nutrient medium. Uptake and storage of phosphate was increased in the transgene expressing lines. This suggests that in tomato, increased flux through the inositol phosphate pathway uncoupled phosphate sensing from phosphate metabolism. Altering the second messenger, InsP(3), revealed multiple coordinated changes in development and metabolism in tomato that have potential for crop improvement.
Khodakovskaya
Mariya
M
Department of Plant Biology, North Carolina State University, Raleigh, NC, USA.
Sword
Courtney
C
Wu
Qian
Q
Perera
Imara Y
IY
Boss
Wendy F
WF
Brown
Christopher S
CS
Winter Sederoff
Heike
H
D018533:Biomass; D050260:Carbohydrate Metabolism; D002338:Carotenoids / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D018744:DNA, Plant / Q000235:genetics; D055864:Droughts; D005638:Fruit / Q000254:growth & development / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D006601:Hexoses / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D000072181:Inositol Polyphosphate 5-Phosphatases; D000077276:Lycopene; D018551:Solanum lycopersicum / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics; D018515:Plant Leaves / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
D018744:DNA, Plant; D006601:Hexoses; D002338:Carotenoids; D015544:Inositol 1,4,5-Trisphosphate; D010744:Phosphoric Monoester Hydrolases; D000072181:Inositol Polyphosphate 5-Phosphatases; D000077276:Lycopene