Calcium Variously Mediates the Effect of Cytokinin on Chlorophyll and LHCPII Accumulation During Greening in Barley Leaves and Cucumber Cotyledons

Journal title

Acta Biologica Cracoviensia s. Botanica




No 2

Publication authors

Divisions of PAS

Nauki Biologiczne i Rolnicze


<jats:title>Abstract</jats:title> <jats:p>During greening, excised etiolated barley leaves and cucumber cotyledons that were depleted of exogenous Ca<jats:sup>2+</jats:sup> by a chelating agent (ethylene glycol-bis (beta aminoethyl ether)-N,N,N`N`-tetraacetic acid, EGTA) showed ∼50% reduced chlorophyll (Chl) accumulation and ∼30% accumulation of apoprotein of the light-harvesting chlorophyll a/b-binding protein complex of photosystem II (LHCPII). The Ca<jats:sup>2+</jats:sup> channel blocker lanthanum chloride (LaCl<jats:sub>3</jats:sub>) applied to cucumber cotyledons reduced LHCPII accumulation more than EGTA did. In both plant mate-rials, cytokinins enhanced chlorophyll accumulation by 50-60% and this effect was completely canceled by EGTA application. Hormones significantly increased LHCPII accumulation but EGTA application reduced that effect in barley leaves by ∼30% and in cucumber cotyledons by ∼80%. A similar effect was observed in LaCl<jats:sub>3</jats:sub>-treated cotyledons. CaCl<jats:sub>2</jats:sub> application boosted chlorophyll accumulation in both plant materials. CaCl<jats:sub>2</jats:sub> applied together with cytokinin reduced the hormonal effect on chlorophyll accumulation by ∼38% in barley leaves and 23% in cucumber cotyledons, but almost totally inhibited cytokinin-stimulated LHCPII accumulation. Our results indicate that calcium variously mediates the effect of cytokinin on chlorophyll and LHCPII accumulation. Cytokinin-induced enhancement of chlorophyll accumulation seems totally dependent on the exogenous pool of Ca<jats:sup>2+</jats:sup>, while Ca<jats:sup>2+</jats:sup>-dependent and Ca<jats:sup>2+</jats:sup>-independent pathways are involved in the hormonal effect on LHCPII accumulation. The effect of cytokinin on the increase of light-induced LHCPII accumulation appears to be sensitive to exogenously applied Ca<jats:sup>2+</jats:sup>, which almost totally blocked the hormonal effect. Our results give indirect evidence that the responses to cytokinin and light act on different events leading to Chl and LHCPII accumulation.</jats:p>


Biological Commission of the Polish Academy of Sciences – Cracow Branch


2015[2015.01.01 AD - 2015.12.31 AD]


eISSN 1898-0295 ; ISSN 0001-5296