Please use this identifier to cite or link to this item:
Title: Differential response of tomato and tobacco to <i style="">Agrobacterium </i>mediated transformation with c<i style="">ytokinin independent -1</i> (<i style="">CKI-1</i>) gene as influenced by cytokinin levels
Authors: Mythili, J B
Saiprasad, G V S
Naveena, C
Rajeev, P R
Upreti, K K
Keywords: <i style="">Agrobacterium</i> mediated transformation
<i style="">CKI-1</i> expression
<i style="">CKI-1</i> gene
Cytokinin levels
Selectable marker
Issue Date: Dec-2011
Publisher: NISCAIR-CSIR, India
Abstract: <i style="">Cytokinin independent-1 </i>(<i style="">CKI-1</i>) gene was identified through its ability to confer cytokinin independent growth in <i style="">Arabidopsis</i> which has led to this gene being advocated as a selectable marker in plant transformation. Keeping this in view, <i style="">CKI-1</i> gene was assessed as a selectable marker by transformation of tobacco (<i style="">Nicotiana tabacum</i>) and tomato (<i style="">Lycopersicon esculentum</i> L.). Overexpression of <i style="">CKI-1</i> gene through <i style="">Agrobacterium</i> mediated transformation in tobacco and tomato conferred cytokinin independent shoot regeneration (in media devoid of cytokinin/plant growth regulators) in tobacco, but not in tomato wherein this ability (cytokinin independence) was conferred to T1 explants of <i style="">CKI-1</i> transgenic tomato plant (T0) regenerated on cytokinin medium. Analysis of cytokinin levels revealed that cytokinin independent growth upon transformation with <i style="">CKI-1</i> gene in tobacco (T0) and tomato (T1) was achieved through maintaining/regulating higher endogenous cytokinin levels and <i>CKI-1</i> gene expression. Levels of <i style="">CKI-1</i> transcripts assayed through quantitative RT-PCR suggested that there seemed to be a threshold level of endogenous cytokinin level, regulated due to external or internal supply via <i style="">CKI-1</i> gene upto which <i style="">CKI-1</i> gene expression correlated with endogenous cytokinin content and beyond that, either the gene expression was not induced or it remains same. With the incorporation of <i style="">CKI-1</i> gene, it appeared that this threshold level of endogenous cytokinin might be reduced in crops like tomato to support shoot regeneration at lower concentration of cytokinin, but could not be made independent of external supply of cytokinin as in tobacco suggesting that use of <i style="">CKI-1</i> gene as an effective alternate selection marker could not be universally applicable across the species. The results of the present study revealed that <i style="">CKI-1</i> gene in addition to enhancing cytokinin levels, was also involved in contributing to the sensitivity to cytokinin and thus served as a positive regulator of cytokinin signal transduction.
Description: 909-918
ISSN: 0975-1009 (Online); 0019-5189 (Print)
Appears in Collections:IJEB Vol.49(12) [December 2011]

Files in This Item:
File Description SizeFormat 
IJEB 49(12) 909-918.pdf564.59 kBAdobe PDFView/Open

Items in NOPR are protected by copyright, with all rights reserved, unless otherwise indicated.