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Usha Vijayraghavan

Professor
Department of Microbiology and Cell biology,
Indian Institute of Science, Bangalore
Ph.D.- California Institute of Technology, California, USA
Post doc- California Institute of Technology, California, USA
Email- uvr@iisc.ac.in

Research overview-

We study cell division and fate in plants and yeasts. Gene networks controlled by rice transcription factors for flowering stem and flower development is a research focus. Post-transcriptional processes fine-tune genomic expression. We examine links between splicing, chromatin status and cell division in yeast with implications for plant gene expression.

Highlights

  • Rice RFL regulates inflorescence form; OsMADS1 a regulatory hub for flowers
  • Contextual roles for essential splicing factors in splicing, chromatin and cell division

Genetic regulators of flowering:

Developmental of multicellular eukaryotes can be controlled by master regulators with cascading effects on cell and tissue fate. In higher plants, flowering requires a dramatic change in the fate of organs that emerge from the apical meristem- a plant growth center. Remarkable diversity exists in flowering time, form and function of the flowering stem (inflorescence) and floral organs. Yet, how evolutionarily conserved regulators confer different architectures are not well understood. Rice, a genetically tractable cereal-grass model, produces modified flowers on higher-order inflorescence branches. Its unique floral organs are the lemma, palea and lodicules whose homology to dicot organs is debated. We study rice inflorescence and flower development with the overall goal to identify networks of transcription factors, chromatin regulators, and signaling pathways for meristem and organ fate.

We study cell division and fate in plants and yeasts. Gene networks controlled by rice transcription factors for flowering stem and flower development is a research focus. Post transcriptional processes fine-tune genomic expression. We examine links between splicing, chromatin status and cell division in yeast with implications for plant gene expression.

Pre-mRNA splicing and links to regulated gene expression and cellular processes:

RNA splicing, an essential step in eukaryotic gene expression, generates functional RNAs from a genes primary transcript. Splicing requires precise excision of non-functional intronic segments and this can expand the complexity of expressed information from any genome. Defects in splicing cause diseases and developmental disorders. Our research on fission yeast factors, Prp18, Slu7 and Prp16, deciphered their intron-context-dependent roles for accurate splice-site selection and for alternative splice isoforms under diverse growth and stress conditions. Further, some splicing factors, mediate centromeric heterochromatinzation and thereby influence cell division and mitosis. As fission yeast gene exon-intron architectures closely resemble those in higher plants, our findings preview how post-transcriptional mechanisms may fine-tune developmental gene expression.

 Future plans:

We will further our investigations of key regulatory networks during rice inflorescence and flower development. Broad aims are to probe spatial and temporal pathways downstream to hub factors like RFL, OsMADS1 and some of their key target genes. Our preliminary data indicate RNA binding and RNA modification factors could influence floral developmental gene expression; these leads will be examined in rice and mechanistic studies could rely on fission yeast as a surrogate. We will continue probing roles for spliceosomal proteins in splicing dependent, and independent pathways that lead to constitutive and/ or facultative heterochromatinzation using fission yeast as a model system.

PhD students
Sandhan Prakash
Amit Sharma
Aniket Girish Parab
Vishnupriya K
Mohamed Zamzam
Sushmita Dutta
Manendra Negi
Owais Ahmad
Postdoctoral fellows
Rashmi Rai (UGC Kothari fellow)
Rakesh Kumar (DBT-RA)
Sharad Singh (Project-SRF/RA)
Sunita Patro (DBT-RA)

Staff members
Rachita Srivastava
Kavitha C.

Junior Scientific Assistant
D Narsimha Murthy