TITLE

Effects of exogenous spermidine on photosynthetic capacity and expression of Calvin cycle genes in salt-stressed cucumber seedlings

AUTHOR(S)
Shu, Sheng; Chen, Lifang; Lu, Wei; Sun, Jin; Guo, Shirong; Yuan, Yinhui; Li, Jun
PUB. DATE
November 2014
SOURCE
Journal of Plant Research;Nov2014, Vol. 127 Issue 6, p763
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
We investigated the effects of exogenous spermidine (Spd) on growth, photosynthesis and expression of the Calvin cycle-related genes in cucumber seedlings ( Cucumis sativus L.) exposed to NaCl stress. Salt stress reduced net photosynthetic rates (P), actual photochemical efficiency of PSII (ΦPSII) and inhibited plant growth. Application of exogenous Spd to salinized nutrient solution alleviated salinity-induced the inhibition of plant growth, together with an increase in P and ΦPSII. Salinity markedly reduced the maximum carboxylase activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Vcmax), the maximal velocity of RuBP regeneration (Jmax), triose-phosphate utilization capacity (TPU) and carboxylation efficiency (CE). Spd alleviated the negative effects on CO assimilation induced by salt stress. Moreover, Spd significantly increased the activities and contents of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and fructose-1,6-biphosphate aldolase (ALD; aldolase) in the salt-stressed cucumber leaves. On the other hand, salinity up-regulated the transcriptional levels of ribulose-1,5-bisphosphate ( RCA), glyceraldehyde-3-phosphate dehydrogenase ( GAPDH) and phosphoribrokinase ( PRK) and down-regulated the transcriptional levels of ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit ( RbcL), ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit ( RbcS), ALD, triose-3-phosphate isomerase ( TPI), fructose-1,6-bisphosphate phosphatase ( FBPase) and 3-phosphoglyceric acid kinase ( PGK). However, Spd application to salt-stressed plant roots counteracted salinity-induced mRNA expression changes in most of the above-mentioned genes. These results suggest that Spd could improve photosynthetic capacity through regulating gene expression and activity of key enzymes for CO fixation, thus confers tolerance to salinity on cucumber plants.
ACCESSION #
99109266

 

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