Our research interests
The main area of research in our lab is in the field of Plant Morphogenesis. We focus on molecular developmental biology with emphasis on phytohormone signaling and vegetative shoot morphogenesis. Another area of work includes DNA markers (e.g., AFLP, microsatellites) for plant population genetics and cladistics. Using plants as bioreactors for production of selected therapeutic proteins (e.g., proteins from snake venom) is a minor area of work in our lab.
Recent accomplishments in understanding the regulation of shoot morphogenesis
- Work on MADS box genes: We have isolated and characterized some genes that are associated with adventitious shoot regeneration. These include a MADS-box cDNA (PkMADS1) from Paulownia kawakamii, which regulates vegetative shoot development and in vitro shoot regeneration from leaf explants (Plant Journal 2002, 29:141-151). Functional analyses based on transgenic plant strategy revealed that PkMADS1 is a novel MADS box protein that regulates vegetative shoot development in Paulownia. Most of the earlier information on MADS box genes was on regulation of flower development. Our work was one of the first to establish a regulatory role for the vegetatively expressed MADS box proteins in plant development.
- Other work on MADS box genes we have completed include the discovery of AGAMOUS-LIKE24 (AGL24) in regulating flowering time in Arabidopsis (PNAS, USA 2002, 99: 16336-16341). Our work established that AGL24 acts as a key intermediary for integrating the flowering signal between LEAFY and SOC1.
- Another MADS box gene we have cloned and characterized is from the primitive gymnosperm Cycas – which has established that the AGAMOUS gene evolved at least 300 million years ago and that its structure and function have been conserved for that period in all the seed plants (Plant Journal 2004, 37: 566-577).
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Phenotypes of expression of the AGAMOUS ortholog CyAG from Cycas (a gymnosperm) in Arabidopsis (Plant J. 2004, 37:566-577) (A) Wild-type Arabidopsis flower. (B) ag-2 mutant flower. (C) Flowers of ag-2 harboring AGenhancer::D35S::CyAG showing that the stamens and carpel are rescued (four stamens). (D) Flowers of ag-2 harboring AGenhancer::D35S::CyAG showing that the mutant is fully rescued (six stamens). se, sepal; pe, petal; st, stamen; ca, carpel. Scale bar = 1 mm. |
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SEM image of an Arabidopsis flower harboring CyAG cDNA in the ag-2 mutant background. Note full rescue of the mutant phenotype. |
- Work on phytohormone signaling: Our current work on a gene encoding for a cytokinin binding protein (originally isolated from petunia) has shown that it is involved in regulating branching, flowering time and adventitious shoot induction from leaf explants. This will be an important candidate gene for developmental enhancement of leafy vegetables where excessive branching and delayed flowering phenotype are highly desirable. Currently, we are attempting to study the proteins that interact with this using the TAP tag approach. This can also contribute to plant biotechnology in the long-term.
- Arising from the above research project and also from our earlier work on ethylene, we have initiated some work on attempts to isolate phytohormone signal transduction intermediates. Recent literature indicates that ethylene and cytokinin signal transduction proceeds by the two-component histidine kinases. Several downstream intermediates have also been isolated by other workers. We intend to attempt to isolate such interacting proteins for the cytokinin-binding protein. This can contribute towards a basic understanding of phytohormone signal transduction during plant development.
Studies such as these help to identify genes for future crop improvement efforts by genetic enhancement of development either by marker assisted plant breeding or by genetic engineering.
- Work on DNA markers: A minor area of research interest in our lab is work on developing DNA markers such as AFLP (phylogeny of Johannesteijsmannia - a palm species) and microsatellites (population dynamics in tropical moss species such as Acanthorrhynchium).
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We have developed microsatellite markers for a tropical moss, Acanthorrhynchium papillatum |