Publications of NIPGR Scientists

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Author: search.filters.author.Jaggi, MonikaSubject: search.filters.subject.Monoterpenoid indole alkaloid pathway

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    Ectopic overexpression of vacuolar and apoplastic Catharanthus roseus peroxidases confers differential tolerance to salt and dehydration stress in transgenic tobacco
    (Springer Science, 2012) Kumar, Santosh; Jaggi, Monika; Sinha, Alok Krishna
    CrPrx and CrPrx1 are class III peroxidases previously cloned and characterized from Catharanthus roseus. CrPrx is known to be apoplastic in nature, while CrPrx1 is targeted to vacuoles. In order to study their role in planta, these two peroxidases were expressed in Nicotiana tabacum. The transformed plants exhibited increased peroxidase activity. Increased oxidative stress tolerance was also observed in transgenics when treated with H(2)O(2) under strong light conditions. However, differential tolerance to salt and dehydration stress was observed during germination of T1 transgenic seeds. Under these stresses, the seed germination of CrPrx-transformed plants and wild-type plants was clearly suppressed, whereas CrPrx1 transgenic lines showed improved germination. CrPrx-transformed lines exhibited better cold tolerance than CrPrx1-transformed lines. These results indicate that vacuolar peroxidase plays an important role in salt and dehydration stress over cell wall-targeted peroxidase, while cell wall-targeted peroxidase renders cold stress tolerance.
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    Effect of loss of T-DNA genes on MIA biosynthetic pathway gene regulation and alkaloid accumulation in Catharanthus roseus hairy roots
    (Springer, 2010) Taneja, Jyoti; Jaggi, Monika; Wankhede, Dhammaprakash Pandhari; Sinha, Alok Krishna
    Hairy roots are generated by integration of T-DNA in host plant genome from root inducing (Ri) plasmid of Agrobacterium rhizogenes and have been utilized for production of secondary metabolites in different plant systems. In Catharanthus roseus, hairy roots are known to show different morphologies, growth patterns, and alkaloid contents. It is also known that during transformation, there is a differential loss of a few T-DNA genes. To decipher the effect of loss of T-DNA genes on the various aspects of hairy roots, ten hairy root clones were analyzed for the presence or absence of T-DNA genes and its implications. It was found that the loss of a few ORFs drastically affects the growth and morphological patterns of hairy roots. The absence of T(R)-DNA from hairy roots revealed increased transcript accumulation and higher alkaloid concentrations, whereas callusing among hairy root lines led to decreased transcript and alkaloid accumulation. Significantly higher expression of MIA biosynthetic pathway genes and low abundance of regulator transcripts in hairy root clones in comparison with non-transformed control roots were also observed. This study indicates that it is not only the integration of T-DNA at certain region of host plant genome but also the presence or absence of important ORFs that affects the expression patterns of MIA biosynthetic pathway genes, regulators, and accumulation of specific alkaloids.