Cytokinin oxidase activity and cytokinin content in roots of sunflower under water stress

Abstract

<span style="font-size: 16.0pt;mso-bidi-font-size:9.0pt;font-family:" times="" new="" roman","serif""="">Contents of trans-zeatin riboside (ZR), dihydrozeatin riboside (DZR) and N⁶-(Δ²- isopentenyl) adenosine (iPA) was quantified by an indirect ELISA using polyclonal antibodies, in the roots xylem sap and leaves of pot grown sunflower plants subjected to water stress (RWC of leaves approximately <span style="font-size:15.5pt;mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif""="">65 <span style="font-size:16.0pt;mso-bidi-font-size:9.0pt;font-family:" times="" new="" roman","serif""="">per cent ). The delivery rates of all three cytokinins decreased significantly under stress. Cytokinin levels also decreased in roots and in leaves of stressed plants. Three-fold increase in cytokinin oxidase activity was observed in stressed roots after polymin P-ammonium sulphate fractionation.Further purification using Con A agarose resulted in elution of protein with cytokinin oxidase activity and was found to be <span style="font-size:15.5pt; mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif""="">30 <span style="font-size:16.0pt;mso-bidi-font-size:9.0pt;font-family:" times="" new="" roman","serif""="">kDa protein on SDS-PAGE.

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