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Interaction between phosphate starvation signalling and hexokinase‐independent sugar sensing in Arabidopsis leaves
Author(s) -
Müller Renate,
Nilsson Lena,
Nielsen Linda Kærgaard,
Hamborg Nielsen Tom
Publication year - 2005
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.2005.00496.x
Subject(s) - hexokinase , sugar , mutant , arabidopsis , biochemistry , sugar phosphates , biology , gene , phosphatase , sucrose phosphate synthase , sucrose , gene expression , chalcone synthase , phosphate , deoxyglucose , enzyme , sucrose synthase , glycolysis , invertase
Expression of selected genes in relation to phosphate (P i ) starvation and sugar sensing was studied in leaves of Arabidopsis. Excised leaf segments with different P status were supplied with combinations of P i and sugars. Sugar‐inducible genes, encoding β‐amylase ( β‐AMY ) and chalcone synthase ( CHS ) , were also induced by P deficiency, and were more strongly regulated by sugars when leaf segments originated from P‐starved plants. Furthermore, transcript levels of the P‐starvation‐inducible genes ACP5 (encoding an acid phosphatase), RNS1 (encoding a ribonuclease) , and IPS1 (unknown function) increased in response to exogenously applied sugars. Supply of P i to the leaf segments reversed both P‐starvation‐induced and sugar‐induced gene expression. These interactions reveal a close relationship between P and sugar sensing. To differentiate between hexokinase‐dependent and hexokinase‐independent sugar sensing the effect of the glucose analogue 2‐deoxyglucose and gene expression in the hexokinase‐1 deficient mutant, gin2‐1, were studied. Both β‐AMY and CHS were induced by supplying sucrose to excised leaves but not by 2‐deoxyglucose, confirming that these genes are regulated by hexokinase‐independent sugar sensing. In the gin2‐1 mutant both β‐AMY and CHS responded clearly to P starvation excluding that hexokinase‐1 mediates the response to P. Similarly, the P‐responding genes, IPS1 and RNS1 were repressed by addition of P i also in the gin2‐1 mutant. In conclusion, several phosphate starvation‐induced genes are also sugar‐induced and hexokinase‐independent sugar sensing in Arabidopsis is strongly intensified by phosphate starvation.