Mechanism of kinetin-induced death of Vicia faba ssp. minor cortex cells

Abstract

Cell death (CD) takes part in the control of all the steps of plant development. It may be induced by endogenous or exogenous factors. This paper presents the results related to mechanism of CD regulation induced by kinetin (Kin) in root cortex of Vicia faba ssp. minor. To explain the process 6-(2-hydroxy-3-methylbenzylamino)purine (PI-55), adenine (Ad), 5'-amine-5'-deoxyadenosine (Ado) and N-(2-chloro-4-piridylo)-N’-phenylurea (CPPU) were applied to (i) block cytokinins (CKs) receptors and toinhibit the activity of (ii) kinases, (iii) oxidases and (iv) phosphoribosyltransferase, respectively. Moreover, ethylene glycol-bis(β-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA), lanthanum chloride (LaCl3) and cyclosporine (CsA) were applied to inactivate calcium ion (Ca2+) channels (i) across all membranes (ALM-Ca2+), including (ii) endoplasmic reticulum (ER-Ca2+) and (iii) mitochondria (MIT-Ca2+), respectively. The effects of these factors were measured by estimation of vitality of cortex cells and amounts of cytosolic Ca2+. Additionally, the role of Sorafenib, inhibitor of RAF kinase, on vitality of cortex cells and ethylene amount as well as the activities of Raf-like kinase and MEK2 with Syntide and Mek2 as substrates, were studied. The results of the paper clarified the suggestion that Kin was converted directly or indirectly to appropriate ribotides (5’-monophosphate ribonucleotides) which cooperated with ethylene and calcium ions signaling pathway activating CD by Kin (Kin-ECD) exogenously (E). Based on the present and previously published results, the scheme of the crosstalk between ethylene signaling MAP kinases, CKs receptor and enzymes of their metabolism in induction of Kin-ECD is proposed.