Virtual Laboratory

Research interests   

 
 

My research interests

I had worked mainly with two crops, rice and rubber. It was very exciting and quite challenging to work with two totally different crop genetic resources, which I loved very much.

a. Rice

I started my scientific career from my post graduation days at the Tamil Nadu Agricultural University (TNAU), when I was working on the hybrid rice (Oryza sativa L) with wild abortive cytoplasmic male sterility (WA-CMS). WA-CMS revolutionized the hybrid rice production in China. We tested three male-sterile lines carrying WA-CMS namely ZhenShan 97A, Er-jiu-Nan 1A and COMS37A crossed with IR50 to identify the restorer system with aim of identifying a series of restorer combinations possessing both high yield and and high fertility restoration. Pollen and spikelet fertility segregated in 9:7 ratio indicating digenic control. A number of selection lines were identified for further evaluation and development of restorers for WA-CMS based cytosteriles. Using these population I could identify strong pleiotropic association of panicle exsertion and male sterility. Interestingly, these genes also favored the phenotypes develop sheath rot (ShR) disease caused by Sarocladium oryzae.

For my doctoral studies, I was attached to work with a Rockefeller Foundation funded project on nitrogen uptake in rice to the TNAU. We were developing a molecular linkage map of rice using a recombinant inbred line (RIL) population developed from a cross between Basmati 370 x ASD 16. ASD 16 is a high yielding indica variety and Basmati 370 is a high grain quality, aromatic rice variety closer to japonica. I had worked on,

  1. Field multiplication and maintenance of RIL population using single seed descent method from F9 onwards.

  2. Agronomic evaluation of RILs under different nitrogen regimes.

  3. Molecular marker profiling of RILs and parents using simple sequence repeat (SSR) markers.

  4. Construction of molecular linkage map.

  5. Biochemical profiling of RILs and parents for primary nitrogen assimilation enzymes like nitrate reductase (NR), glutamine synthetase (GS) and glutamate synthase (GOGAT).

  6. Designing primers specific to unspliced coding sequences and upstream promoter specific regions for key nitrogen assimilation enzymes, ammonium and nitrate transporter genes.

  7. Mapping of Quantitative trait loci (QTLs) linked to nitrogen assimilation and associated agronomic phenotypes.

  8. Determination of QTL x nitrogen regime interaction

  9. Identification of nitrogen sensitive locus for helping the development of low nitrogen stable genotypes in future through Marker assisted selection (MAS)

  10. The RILs were also subjected cooked grain quality evaluation and QTLs  associated with these traits also were identified.

During this period, I used software such as MAPMAKER/EXP, QTLMAPPER, PLABQTL, QTL Cartographer, SAS, EPISTAT, MAPCHART, QTL Network, FastPCR, Primer 3 etc., apart from all the procedures and equipments to run molecular and biochemical profiling of RILs. At the end of my doctoral, I could identify a specific chromosomal region on the long arm of chromosome 3, particularly sensitive to nitrogen, which associated strongly with yield under different nitrogen regimes and biomass production. This region also showed high association with GS activity. This region is further awaiting fine mapping attempts.

While at TNAU, I also worked with MAS for drought tolerance using near flowering lines (NFL) of the crosses between IR 64 x Norungan and IR 50 x Norungan. Norungan was a landrace known for its drought tolerance. Panicle exsertion was found to be a secondary trait highly associated in determining yield under the reproductive stage moisture stress. We have worked on QTL validation and found specific genomic regions associated with drought tolerance were favored by alleles from Norungan and strongly associated with yield under reproductive phase moisture stress. We have also worked on fingerprinting of rice accessions including landraces suitable for drought tolerance and medicinal importance.

b. Rubber

My earlier work at at the Rubber Research Institute of India (RRII) was with Hevea brasiliensis genetic resources, especially with the wild Hevea collections brought in from Rubber Research Institute of Malaysia (RRIM). These collections were done during 1981 at the centre of primary diversity in Brazil, specially from the states of Acre, Rondonio and Mato Grosso, in an international expedition organised by the International Rubber Research and Development Board (IRRDB), London, UK. The collections were maintained at RRIM then on. With these germplasm providing tremendous potential for improvement of Hevea, we started to work on,

i.    Conserving the germplasm ex situ at our own gardens as source bush nurseries.
ii.   Characterization of the germplasm lines and development of passport data.
iii.  Quantitative evaluation and numerical taxonomy
iv.  Determination of provenance diversity
v.   Genetic potential for pre-breeding

I worked with the wild germplasm at North-East India, where Hevea was experiencing low temperature stress. We could identify few promising accessions based on secondary traits. Some selections were sent to other hot spot regions of India for further evaluation. Parallelly, we could also identify ideal selections for commercial cultivation at North East India, from the cultivated germplasm originated from the Wickham collections dating back to 1876. My studies were focused on cold stress and we worked on,

i.    Growth pattern of different clones under the agroclimate at North East India
ii.   Yielding trend of different clones under cold and non-cold regimes
iii.  Genotype x environment interaction studies
iv.  Selection combining yield and stability
v.   Recombination breeding

With the tremendous exposure with a abiotic stress situation, I continued to work with Hevea breeding lines at another non-traditional region at Coastal Karnataka. The region was characterized by heavy rains, hot summer, with excessive surface soil heating due to high deposits of iron ore native to this region. This region supports the growth of Hevea well, but require specific care in immature period to ward of the damages due to sun scorch. But, more prevalent were various diseases affecting Hevea, starting from the leaf diseases like, Phytophthora leaf fall, Colletotrichum leaf spot, Corynespora leaf fall, Oidium powdery mildew and stem diseases like pink disease caused by Corticium salmonicolor, patch canker, bark rot and brown root disease. Selecting high and stable yielding clones with disease tolerance was the focus of crop improvement at Coastal Karnataka. Here I worked on,

i.    Growth pattern of clones under the agroclimate of Coastal Karnataka
ii.   Clonal performance for yield and associated traits, for commercial selection
iii.  Identification of disease tolerance of clones

c. Other crops

At TNAU, I have worked for the induction of cytoplasmic male sterility in pigeon pea (Cajanus cajan L.), by attempting to transfer of alien cytoplasm from Atylosia cajanifolia, Cajanus scarabaeoides, C. acutifolius and C. platycarpus. Embryo rescue techniques were attempted to salvage inter-specific hybrids. Molecular profiling using isozyme and DNA markers of the successful hybrids was done. Successful crosses were obtained in field. I was also involved in molecular characterization and profiling of interspecifc crosses of Sesamum and studied the pollen pistil interaction as the pre-zygotic hybridization barriers in many wide crosses of Sesamum. DNA marker profiling of a hybrid between S. indicum x S. radiatum was attempted.

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