ANANIEVA, K., ANANIEV, E. D., DONCHEVA, S., STEFANOV, D., MISHEV, K., KAMÍNEK, Miroslav, MOTYKA, Václav, DOBREV, Petre, MALBECK, Jiří. Local induction of senescence by darkness in Cucurbita pepo (zucchini) cotyledons or the primary leaf induces opposite effects in the adjacent illuminated organ. Plant Growth Regulation. 2011, 65(3), 459-471. ISSN 0167-6903. E-ISSN 1573-5087

Local darkening of zucchini cotyledons or the adjacent leaf affected in an organ-specific manner the adjacent ones which remained under the initial light regime. Darkening of the pair of cotyledons induced a reduction of total cytokinin (CK) levels and increase CK oxidase/dehydrogenase (CKX) activity in the adjacent illuminated primary leaf. Content of abscisic acid (ABA) was increased which correlated with reduced stomatal aperture. In contrast, darkening of adjacent primary leaf led to the increase in total CK levels in parallel with decreased CKX activity, decrease of ABA content in correlation with increased stomatal aperture. Three photosynthesis-related genes psbA, psaB and rbcL remained almost unaffected in both illuminated organs. Results indicate involvement of CKX and ABA signaling in the control of communication mechanisms between cotyledons and the primary leaf which could operate in response to changing environmental factors.