Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/14394
Title: Cloning and characterization of diamine oxidase and glutamate decarboxylase genes of mustard (Brassica juncea) and their roles in shoot morphogenesis in vitro
Authors: JIAO YUXIA
Keywords: mustard, PAs, DAO, GAD, shoot regeneration, ethylene
Issue Date: 29-Nov-2004
Source: JIAO YUXIA (2004-11-29). Cloning and characterization of diamine oxidase and glutamate decarboxylase genes of mustard (Brassica juncea) and their roles in shoot morphogenesis in vitro. ScholarBank@NUS Repository.
Abstract: The main aim of this study was to elucidate the role of polyamine catabolism in shoot morphogenesis in vitro in relation to diamine oxidase (DAO) and glutatmate decarboxylase (GAD). To achieve this, one genomic DAO clone, gBjDAO, was isolated and characterized in mustard. DAO expressed at very low levels in mustard and expression was regulated, at least in part, at the promoter. The deletion of 5a??-UTR greatly downregulated DAO expression in the whole plant and expression in the root was completely suppressed. Exogenous applications of H2O2, paraquat and salicylic acid were shown to downregulate DAO expression, which might be feedback-inhibited by H2O2. In addition to DAO, four members (mGAD1, mGAD2, mGAD4a and mGAD4b) of the GAD gene were also isolated from mustard. These GAD genes were shown to express differentially in different organs and in response to external stimuli. Cultured tissues derived from transgenic plants that overexpressed DAO produced higher levels of ethylene and possessed higher putrescine/spermidine ratios but tissues were poorly regenerative. This was contrary to highly regenerative tissues from transgenic plants expressing antisense DAO and wild type, which showed lower levels of ethylene production with lower putrescine/spermidine ratios. However, overexpression and downregulation of GAD had no apparent effect on shoot regeneration in vitro.
URI: http://scholarbank.nus.edu.sg/handle/10635/14394
Appears in Collections:Ph.D Theses (Open)

Show full item record
Files in This Item:
File Description SizeFormatAccess SettingsVersion 
whole thesis.pdf5.87 MBAdobe PDF

OPEN

NoneView/Download
thesis spine.pdf8.19 kBAdobe PDF

OPEN

NoneView/Download

Page view(s)

270
checked on Dec 11, 2017

Download(s)

493
checked on Dec 11, 2017

Google ScholarTM

Check


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