Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.1.14 (SPS)
 813 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The primary target for light-chilling stress in chilling-sensitive cucumber leaves is the chloroplast Cu,Zn-Superoxide dismutase, followed by subsequent inactivation of the photosystem (PS) I by reactive oxygen species (ROS). To test this hypothesis, two rice cultivars that were different in their ecological origins (a chilling-resistant Stejaree 45 and a chilling-sensitive Milyang 23) were evaluated with respect to photosynthetic properties, the ROS scavenging system, and expression of genes that are involved in sucrose synthesis and allocation upon the light-chilling stress. As expected, when the leaves were exposed to various low temperatures with illumination (150 micromol m(-2)s(-1)) for 6 h, the leaf photosynthesis of Milyang 23 decreased faster than that of Stejaree 45. The light-chilling induced differential photoinhibition of photosynthesis between the two cultivars was caused by the photoin-activation of PSII but not of PSI, since the potential quantum yield of PSII followed a similar trend to the changes in photosynthetic rates. The activities of the two chloroplastic antioxidant enzymes (superoxide dismutase and ascorbate peroxidase) that are known to be sensitive to oxidative stress were barely affected by the light-chilling treatments. Among various genes in sucrose metabolism (such as cytosolic FBPase, SPS, SUT, SuSy, and AGPase), the transcript levels of SuSy in Milyang 23 were significantly decreased by light-chilling stress compared to that of Stejaree 45. Based on these results, we propose that PSII, not PSI, is the sensitive site for light-chilling stress in chilling-sensitive rice. The extent of PSII photoinhibition depends on its capacity for the photochemical utilization of light.
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PMID:Differential susceptibility of photosynthesis to light-chilling stress in rice (Oryza sativa l.) depends on the capacity for photochemical dissipation of light. 1213 82

The expression of sucrose-phosphate synthase II (SPSII) and sucrose transporters ShSUT1A and ShSUT4 were determined by RT-PCR and qRT-PCR in the sink and source leaves and in rind and pith of mature internodes of four high-yielding Hawaiian sugarcane cultivars. Expression of SPSII, ShSUT1A, and ShSUT4 was lower in pith than in rind, except in one cultivar, but else quite similar in the cultivars. The strong expression of transporter ShSUT4 in the rind of the internodes may hint to a special role of ShSUT4 in the rind. ShSUT4-expression in the sink and source leaves was similar in all four cultivars, whereas large differences were found for the expression of ShSUT1A and SPSII between the source and sink leaves and between the cultivars. The levels of sucrose precursors were doubled in source leaves compared to sink leaves, whereas they were higher in immature internode compared to mature internode. The role of sucrose transporters and SPSII in leaves and internodes is discussed, but the large differences, which were observed in the transcript levels of SPSII and sucrose transporters between some cultivars, although all the cultivars were similarly high-yielding cultivars, show that SPSII and SUT transcript levels cannot be used as indicators of high-yield cultivars.
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PMID:Assessment of sucrose transporters, metabolites and sucrose phosphate synthase in different sugarcane tissues. 2887 8