Open AccessMetabolic Implications in the Biochemical Responses to Iron Deficiency in Cucumber (Cucumis sativus L.) Roots
Author(s) -
Giuseppina Rabotti,
Patrizia De Nisi,
Graziano Zocchi
Publication year - 1995
Publication title -
plant physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.554
H-Index - 312
eISSN - 1532-2548
pISSN - 0032-0889
DOI - 10.1104/pp.107.4.1195
Subject(s) - cucumis , phosphoenolpyruvate carboxylase , rhizosphere , carbon fixation , biochemistry , cytosol , lactate dehydrogenase , nad+ kinase , pyruvate carboxylase , chemistry , biology , enzyme , botany , photosynthesis , bacteria , genetics
Strategy I plants respond to Fe deficiency by inducing morphological and biochemical modifications at the root level that are apt to make iron available for uptake. Cucumber (Cucumis sativus L.) grown in the absence of Fe has been shown to increase the capacity to acidify the rhizosphere and Fe3+ reduction activity. We have determined in these roots some metabolic activities that might be correlated with the increased proton extrusion. Proton efflux from roots may be followed by a mechanism regulating the cytosolic pH according to the pH-stat theory. Roots grown in the absence of Fe showed an increase in dark 14CO2 fixation and organic acid synthesis and a 6-fold increase in the extractable phosphoenolpyruvate carboxylase activity with respect to the control roots. Dehydrogenase activities producing cytosolic NAD(P)H were also increased under Fe deficiency. The presence of Fe2+, but not Fe3+, inhibited dark 14CO2 fixation in a range between 24 and 52% but did not show any effect on the in vitro phosphoenolpyruvate carboxylase activity.