Jitendra P. Khurana

Professor (Rtd), J.C. Bose National Fellow (SERB), Department of Plant Molecular Biology 
Telephone No.: 091 11 24115126 (work), 091 11 24119090 (home) Fax: 091 11 24111208, 24115270; E-mail: khuranaj@genomeindia.org

Photoperception and Signal Transduction Mechanisms in plants; Plant Hormone Action Mechanisms; Structural and Functional Genomics in Plants

Research Interests

Our group has contributed extensively to the area of light perception and signal transduction mechanisms in plants. Some of the initial work on Arabidopsis mutants lead to the identification of the blue light receptor, phototropin1 (PHOT1), which in fact remained elusive for over a century. During a screen for phototropism mutants, we also identified constitutively photomorphogenic mutants that display de-repression of gene expression in dark and flower precociously. Some other novel mutants characterized include bls1cnr1 and prl2, which are defective in light, hormone and sugar signaling. The genes encoding blue light receptors, CRY1 and CRY2, have been isolated and sequenced from Brassica napus and CRY2 coding gene from rice and functionally validated in transgenics for their role in regulating agronomically important traits like plant height and flowering time. Based on the microarray analysis of transgenics, it has become obvious that CRY1 regulates plant height largely by modulating the expression of genes involved in GA biosynthesis, auxin signalling and cell wall modification enzymes. In addition, the genes for red/far-red sensing phytochromes (PHYA and PHYC) have been characterized from hexaploid wheat and their evolutionary relationship examined. More recently, we have chracterized rice bZIP protein coding genes, ortologous to HY5 of Arabdopsis. One of these rice orthologs, OsbZIP48, could functionally complement hy5 mutant of Arabidopsis, as also caused semi-dwarfism when over-expressed in rice; strikingly, its T-DNA insertion line in rice was seedling lethal. In contrast to AtHY5, OsbZIP48 protein was found to be stable in dark. Thus, it appears that OsbZIP48 has undergone neofunctionalization during the course of evolution in monocot systems like rice.

In the past over 15 years, the focus in my lab has gradually shifted towards structural and functional genomics in plants. Our group at South Campus has actively participated in sequencing rice, tomato and wheat genomes as part of the International Consortia. Using genome sequence resources, we have phylogenetically analyzed and characterized several rice gene families, including auxin-inducible AUX/IAASAUR and GH3 gene families, and a sub-group of cytokinin-inducible Response Regulator (RR) genes. We have identified a few interacting partners of one of these AUX/IAA proteins and demonstrated the role of one of them, Di-19, in abiotic stress signalling. In addition, an extensive bioinformatic analysis has also been carried out for two very important classes of transcription factor genes in rice encoding F-box proteins (involved in 26S proteasome-mediated protein degradation) and the basic leucine zipper (bZIP) proteins, known to be involved in light and hormone signalling. How the expression of these genes is altered during various stages of panicle and seed development and under various abiotic stress conditions has been analyzed for prioritization of genes for functional analysis in transgenics adopting over-expression and RNAi approach. In addition to elucidating the role of OsbZIP48 in light signalling (discussed above), another rice bZIP protein (OsbZIP62; a homolog of AtFD) coding gene, has been characterized in detail. Functional analysis by raising RNAi lines and carrying out protein-protein interaction studies by Y2H, BiFC and pull-down assays, has revealed that OsbZIP62 interacts with the mobile FT protein (florigen) to regulate the expression of genes involved in floral transition and panicle development in rice. We have also elucidated the role of one of the F-box protein coding genes, OsFBK1, a component of E3 ligase, in lignin biosynthesis by regulating turnover of cinnamoyl-CoA reductase during anther and root development in rice.

We also have interest in genes involved in chromatin modulations, which are turning out to be of great significance in regulation of gene expression in living organisms. The genes encoding polycomb group/SET domain proteins have also been annotated and classified from rice. One such gene that preferentially expresses in the reproductive tissue has been characterized functionally. When over-expressed, it could restore telomere silencing in a yeast mutant, indicating functional conservation of gene repression mechanisms in eukaryotic chromatin. In addition, genes encoding topoisomerase 6 (TOP6A1, A2, A3 and TOP6B), a subclass of topoisomerase II, have been characterized from rice. When rice TOP6A1, TOP6A3 and TOP6B genes were over-expressed in Arabidopsis (as a model system), all the genes independently conferred tolerance to abiotic stress, suggesting their use in transgenic manipulation for stress tolerance in crop plants like rice.

Select Publications:
Out of nearly 150 papers published, a select list of 15 is provided.
  1. Borah, P. and Khurana, J.P. 2018. The OsFBK1 E3 ligase subunit affects anther and root secondary cell wall thickenings by mediating turn-over of a cinnamoyl-CoA reductase. Plant Physiology 176: 2148–2165.
  2. Burman, N., Bhatnagar, A. and Khurana, J.P. 2018. OsbZIP48, orthologous to AtHY5, exerts pleiotropic effects in light-regulated plant development. Plant Physiology 176: 1262-1285 (In Focus Issue “Energy: Light and Oxygen”).
  3. International Wheat Genome Sequencing Consortium (IWGSC) 2018. Shifting the limits in wheat research and breeding using a fully annotated reference genomeScience 361 (6403): eaar7161 (1-13).
  4. Borah, P., Sharma, E., Kaur, A., Chandel, G., Mohapatra, T., Kapoor, S. and Khurana, J.P. 2017. Analysis of the drought-signalling network in two contrasting varieties of rice by employing microarray-based transcriptomics approach. Scientific Reports 7: 42131. doi: 10.1038/srep42131. 
  5. Mishra, S. and Khurana, J.P. 2017. Emerging roles and new paradigms in signalling mechanisms of plant cryptochromes. Crit. Rev. Plant Sci. 36: 89-115.
  6. The International Wheat Genome Sequencing Consortium (IWGSC) 2014. A chromosome-based draft sequence of the hexaploid bread wheat (Triticum aestivum) genome. Science 345: 1251788-1 to 1251788-11.
  7. Sharma, P., Chatterjee, M., Burman, N. and Khurana, J.P. 2014. Cryptochrome 1 regulates growth and development in Brassica through alteration in the expression of genes involved in light, phytohormone and stress signaling. Plant Cell Environ. 37: 961-977.
  8. The Tomato Genome Sequencing Consortium 2012. The tomato genome sequence provides insights into fleshy fruit evolution. Nature 485: 635-641. (Authored as one of the Principal Investigators).
  9. Jain, M. and Khurana, J.P. 2009. An expression compendium of auxin-responsive genes during reproductive development and abiotic stress in rice. FEBS J. 276: 3148-3162.
  10. Nijhawan, A., Jain, M., Tyagi, A.K. and Khurana, J.P. 2008. A genomic survey and gene expression analysis of basic leucine zipper (bZIP) transcription factor family in rice. Plant Physiology 146: 333-350.
  11. Jain, M., Nijhawan, A., Arora, R., Agarwal, P., Ray, S., Sharma, P., Kapoor, S., Tyagi, A.K. and Khurana, J.P. 2007. F-box proteins in rice. Genome-wide analysis, classification, temporal and spatial gene expression during panicle and seed development, and regulation by light and abiotic stress. Plant Physiology 143: 1467-1483.
  12. Jain, M., Tyagi, A.K. and Khurana, J.P. 2006. The over-expression of putative topoisomerase 6 genes from rice confers stress tolerance in transgenic Arabidopsis plants. FEBS Journal 273: 5245-5260.
  13. Chatterjee, M., Sharma, P. and Khurana, J.P. 2006. CRYPTOCHROME 1 from Brassica napus is upregulated by blue light and controls hypocotyl/stem growth and anthocyanin accumulation. Plant Physiology 141: 61-74.
  14. International Rice Genome Sequencing Program 2005. The map-based sequence of the rice genome. Nature 436: 793-800.
  15. Khurana, J.P. and Poff, K.L. 1989. Mutants of Arabidopsis thaliana with altered phototropism. Planta 178: 400-406.