Ananieva K, Ananiev ED, Doncheva S, Georgieva K, Tzvetkova N, Kamínek M, Motyka V, Dobrev P, Gajdošová S, Malbeck J
PHYSIOLOGIA PLANTARUM
134:
609-623,
2008
Klíčová slova:
Abstrakt:
Darkness mediates different senescence-related responses depending on the
targeting of dark treatment (whole plants or individual leaves) and on the organs
that perceive the signal (leaves or cotyledons). As no data are available on the
potential role of darkness to promote senescence when applied to individual
cotyledons, we have investigated how darkness affects the progression of senescence
in either a single or both individually darkened cotyledons of young
10-day-old Cucurbita pepo (zucchini) seedlings. Strong acceleration of senescence
was observed when both cotyledons were darkened as judged by the
damage in their anatomical structure, deterioration of chloroplast ultrastructure
in parallel with decreased photosynthetic rate and photochemical quantum
efficiency of PSII. In addition, the endogenous levels of cytokinins (CKs) and IAA
were strongly reduced. In a single individually darkened cotyledon, the structure
and function of the photosynthetic apparatus aswell as the contents of endogenous
CKs and IAAweremuch less affected by darkness, thus suggesting inhibitory effect
of the illuminated cotyledon on the senescence of the darkened one. Apparently,
the effect of darkness to accelerate/delay senescence in a single darkened
cotyledon depends on the light status of the other cotyledon from the pair. The
close positive correlation between CK content and the activity of CK oxidase/
dehydrogenase (CKX; EC 1.4.3.18/1.5.99.12) suggested that CKX was essentially
involved in the mechanisms of downregulation of endogenous CK levels. Our
results indicated that CKX-regulated CK signaling could be a possible regulatory
mechanism controlling senescence in individually darkened cotyledons.
Fulltext: kontaktujte autory z ÚEB
Autoři z ÚEB: Petre I. Dobrev,
Silvia Gajdošová,
Miroslav Kamínek,
Jiří Malbeck,
Václav Motyka
Čeština
English