Publications of NIPGR Scientists

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Author: search.filters.author.Vishwakarma, Niraj KumarSubject: search.filters.subject.root

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    Root-specific expression of chickpea cytokinin oxidase/dehydrogenase 6 leads to enhanced root growth, drought tolerance and yield without compromising nodulation
    (John Wiley & Sons, 2020) Khandal, Hitaishi; Gupta, Santosh Kumar; Dwivedi, Vikas; Mandal, Drishti; Sharma, Nilesh Kumar; Vishwakarma, Niraj Kumar; Pal, Lalita; Choudhary, Megha; Francis, Aleena; Malakar, Paheli; Singh, Nagendra Pratap; Sharma, Kapil; Sinharoy, Senjuti; Singh, Narendra Pratap; Sharma, Rameshwar; Chattopadhyay, Debasis
    Cytokinin group of phytohormones regulate root elongation and branching during post‐embryonic development. Cytokinin degrading enzymes cytokinin oxidases/dehydrogenases (CKXs) have been deployed to investigate biological activities of cytokinin and to engineer root growth. We expressed chickpea cytokinin oxidase 6 (CaCKX6) under the control of a chickpea root‐specific promoter of CaWRKY31 in Arabidopsis thaliana and chickpea having determinate and indeterminate growth patterns, respectively, to study the effect of cytokinin depletion on root growth and drought tolerance. Root‐specific expression of CaCKX6 led to a significant increase in lateral root number and root biomass in Arabidopsis and chickpea without any penalty to vegetative and reproductive growth of shoot. Transgenic chickpea lines showed increased CKX activity in root. Soil‐grown advanced chickpea transgenic lines exhibited higher root‐to‐shoot biomass ratio and enhanced long‐term drought tolerance. These chickpea lines were not compromised in root nodulation and nitrogen fixation. The seed yield in some lines was up to 25% higher with no penalty in protein content. Transgenic chickpea seeds possessed higher levels of zinc, iron, potassium and copper. Our results demonstrated the potential of cytokinin level manipulation in increasing lateral root number and root biomass for agronomic trait improvement in an edible legume crop with indeterminate growth habit.
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    CBL-interacting protein kinase 25 contributes to root meristem development
    (Oxford University Press, 2019) Meena, Mukesh Kumar; Vishwakarma, Niraj Kumar; Tripathi, Vineeta; Chattopadhyay, Debasis
    Coordination of auxin and cytokinin activities determines root meristem size during post-embryonic development. Calcineurin B-like proteins (CBLs) and their interacting protein kinases (CIPKs) constitute signaling modules that relay calcium signals. Here we report that CIPK25 is involved in regulating the root meristem size. Arabidopsis plants lacking CIPK25 expression displayed a short root phenotype and a slower root growth rate with less meristem cells. This phenotype was rescued by restoration of CIPK25 expression. CIPK25 interacted with CBL4 and -5, and displayed a strong gene expression in the flower and root except in the cell proliferation domain in the root apical meristem. Its expression in root was positively and negatively regulated by auxin and cytokinin, respectively. cipk25 T-DNA insertion line was compromised in auxin transport and auxin-responsive promoter activity. cipk25 mutant line showed altered expression of auxin efflux carriers and an Aux/IAA family gene SHY2. Decreased PIN1 and PIN2 expression in cipk25 mutant line was completely restored when combined with SHY2 loss-of-function mutation resulting in recovery of root growth. SHY2 and PIN1 expression was partially regulated by cytokinin even in absence of CIPK25, suggesting existence of CIPK25-independent cytokinin signaling pathway(s) as well. Our results suggested a role of CIPK25 in root meristem development.