Phenotypic plasticity is an important response mechanism of plants to environmental heterogeneity. Here, we explored the genetic basis of plastic responses of Arabidopsis thaliana to water deficit by experimentally mapping quantitative trait loci (QTL) in two recombinant inbred populations (Cvi x Ler and Ler x Col). We detected genetic variation and significant genotype-by-environment interactions for many traits related to water use. We also mapped 26 QTL, including six for carbon isotope composition (delta13C). Negative genetic correlations between fruit length and fruit production as well as between flowering time and branch production were corroborated by QTL colocalization, suggesting these correlations are due to pleiotropy or physical linkage. Water-limited plants were more apically dominant with greater root:shoot ratios and higher delta13C (higher water-use efficiency) when compared to well-watered plants. Many of the QTL effects for these traits interacted significantly with the irrigation treatment, suggesting that the observed phenotypic plasticity is genetically based. We specifically searched for epistatic (QTL-QTL) interactions using a two-dimensional genome scan, which allowed us to detect epistasis regardless of additive genetic effects. We found several significant QTL-QTL interactions including three that exhibited environmental dependence. These results provide preliminary evidence for proposed genetic mechanisms underlying phenotypic plasticity.

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Computational Methods in Sciences and Engineering, and Computers & Mathematics with Applications. Besides, he has coauthored seven books including the most recent one entitled "Computational Error and Complexity in Science and Engineering (with V. Lakshmikantham), Elsevier, Amsterdam, 2005. He had also authored several book chapters. All his research and book publications are in several areas mainly in computational science. He has been teaching several courses in areas such as stochastic and deterministic operations research, applied statistical analysis, and computational mathematics since late sixties. Further, he has been a member of the editorial board of international journals such as Computer Science and Informatics (India), and Neural, Parallel and Scientific Computations (USA). He has also been cited in Marquis Whos Who (Sep 2005).