Analysis of cDNA Clones Encoding Sucrose-Phosphate Synthase in Relation to Sugar Interconversions Associated with Dehydration in the Resurrection Plant Craterostigma plantagineum Hochst

Abstract

Sucrose-phosphate synthase (SPS) is a key enzyme in the regulation of sucrose metabolism, being responsible for the synthesis of sucrose 6-phosphate from fructose 6-phosphate and uridine 5 ' -diphosphate-glucose. W e report on the isolation and characterization of cDNA clones encoding SPS from Craferosfigma planfagineum Hochst., a resurrection plant in which the accumulation of sucrose is considered to play an important role in tolerance to severe protoplastic dehydration. Two distinct classes of cDNAs encoding SPS were isolated from C. plantagineum, and are represented by the clones Cpspsl and CpspsZ. l h e transcripts corresponding to both cDNAs decrease to very low levels in dehydrating leaves of C. plantagineum. Only the Cpspsl transcript occurs in the roots, where it is present at a higher leve1 than in leaves and increases upon dehydration of the plant. Higher enzymatic activities have been determined in protein extracts of dehydrated tissues compared with untreated tissues, which correlates with an increase in protein levels. It is suggested that the overall regulation of SPS is strongly influenced by the changing composition of the cytoplasm in C. plantagineum leaves during the dehydration-rehydration cycle.

Differential Expression of Sucrose-Phosphate Synthase Isoenzymes in Tobacco Reflects Their Functional Specialization during Dark-Governed Starch Mobilization in Source Leaves

“…A similar expression pattern has been reported for a member of the rice (Oryza sativa) SPS B family that was highly expressed in immature inflorescences, and it has been proposed that in rice the SPS B isoform might be involved in the supply of carbon to developing pollen grains (Chávez-Bárcenas et al, 2000). Expression of the B isoform seems to be induced by stress-related environmental factors in kiwi (Actinidia deliciosa; Fung et al, 2003) and in C. plantagineum (Ingram et al, 1997), however, it is currently not known whether this holds also true for NtSPSB.…”

“…Total (dpm) 6,518 6 1,855 5,339 6 1,445 5,181 6 1,573 8,374 6 2,087 8,913 6 3,079 Insoluble 39.2 6 3.5 42.1 6 4.1 42.7 6 3.8 41.3 6 3.5 42.5 6 5.2 Soluble 60.8 6 3.5 57.9 6 4.1 57.3 6 3.8 58.7 6 3.5 57.5 6 5.2 Neutral 46.7 6 4.6 48.7 6 9.5 41.6 6 8.0 41.9 6 4.3 40.6 6 14.4 Anionic 8.7 6 3.8 8.2 6 2.0 9.9 6 3.8 7.4 6 0.5 7.8 6 2.9 Cationic 6.9 6 0.7 8.8 6 1.4 9.1 6 0.6 8.1 6 0.8 7.9 6 0.7 1997), citrus (Komatsu et al, 1996), Oncidium goldiana (Li et al, 2003), and Craterostigma plantagineum (Ingram et al, 1997). All regulatory phosphorylation sites known for SPS are well conserved among A-family members from different species (Langenkämper et al, 2002).…”

Desiccation Tolerance in the Resurrection Plant Craterostigma plantagineum. A Contribution to the Study of Drought Tolerance at the Molecular Level

“…C. plantagineum possesses a set of genes encoding isoenzymes of Suc synthase and Suc phosphate synthase (Ingram et al, 1997;Kleines et al, 1999), which are differentially expressed. Besides these enzymes and the dehydration-induced expression of cytosolic glyceraldehyde dehydrogenase, it has been proposed that transketolase contributes to the conversion of octulose to Suc.…”

Cloning and characterization of the drought-resistance OsRCI2-5 gene in rice (Oryza sativa L.)

“…Xu et al (1996) used the microprojectile bombardment method to transfer a barley late embryogenesis abundant (LEA) gene into rice and detected a significant increase in LEA protein as well as obviously improved rice drought tolerance, which suggested that the LEA protein could protect rice against drought stress-related injury. In the presence of the overexpression of P5CS and δ-OAT, two key genes involved in the proline biosynthesis process, proline content was increased and rice drought resistance was significantly enhanced (Ingram et al, 1997;Wu et al, 2003). Igarashi et al (1997) isolated P5C cDNA (cosP5CS) from Akibare and found that P5CS could be induced by all stress factors including drought.…”