Expression of a bifunctional fusion of the Escherichia coli genes for trehalose-6-phosphate synthase and trehalose-6-phosphate phosphatase in transgenic rice plants increases trehalose accumulation and abiotic stress tolerance without stunting growth.
Trehalose plays an important role in stress tolerance in plants. Trehalose-producing, transgenic rice (Oryza sativa) plants were generated by the introduction of a gene encoding a bifunctional fusion (TPSP) of the trehalose-6-phosphate (T-6-P) synthase (TPS) and T-6-P phosphatase (TPP) of Escherichia coli, under the control of the maize (Zea mays) ubiquitin promoter (Ubi1). The high catalytic efficiency (Seo et al., 2000) of the fusion enzyme and the single-gene engineering strategy make this an attractive candidate for high-level production of trehalose; it has the added advantage of reducing the accumulation of potentially deleterious T-6-P. The trehalose levels in leaf and seed extracts from Ubi1::TPSP plants were increased up to 1.076 mg g fresh weight(-1). This level was 200-fold higher than that of transgenic tobacco (Nicotiana tabacum) plants transformed independently with either TPS or TPP expression cassettes. The carbohydrate profiles were significantly altered in the seeds, but not in the leaves, of Ubi1::TPSP plants. It has been reported that transgenic plants with E. coli TPS and/or TPP were severely stunted and root morphology was altered. Interestingly, our Ubi1::TPSP plants showed no growth inhibition or visible phenotypic alterations despite the high-level production of trehalose. Moreover, trehalose accumulation in Ubi1::TPSP plants resulted in increased tolerance to drought, salt, and cold, as shown by chlorophyll fluorescence and growth inhibition analyses. Thus, our results suggest that trehalose acts as a global protectant against abiotic stress, and that rice is more tolerant to trehalose synthesis than dicots.
Jang
In-Cheol
IC
Department of Biological Science, Myongji University, Yongin 449-728, Korea.
Oh
Se-Jun
SJ
Seo
Ju-Seok
JS
Choi
Won-Bin
WB
Song
Sang Ik
SI
Kim
Chung Ho
CH
Kim
Youn Shic
YS
Seo
Hak-Soo
HS
Choi
Yang Do
YD
Nahm
Baek Hie
BH
Kim
Ju-Kon
JK
D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D000595:Amino Acid Sequence; D001483:Base Sequence; D002734:Chlorophyll / Q000378:metabolism; D003080:Cold Temperature; D004190:Disasters; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D005964:Glucosyltransferases / Q000235:genetics* / Q000378:metabolism; D012275:Oryza / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D010641:Phenotype; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D014026:Nicotiana / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D014198:Trehalase / Q000378:metabolism; D014199:Trehalose / Q000096:biosynthesis*
D011993:Recombinant Fusion Proteins; D002734:Chlorophyll; D012965:Sodium Chloride; D014199:Trehalose; D005964:Glucosyltransferases; C023180:trehalose-6-phosphate synthase; C023178:trehalose-phosphatase; D010744:Phosphoric Monoester Hydrolases; D014198:Trehalase