Browsing by Author "Purama, Ravi Kiran"

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Identification and downstream analyses of domains amplified in plant genomes: The case of StAR-related lipid transfer (START) domains in rice
(Springer Nature Publishing AG, 2021) Mahtha, Sanjeet Kumar; Purama, Ravi Kiran; Kumari, Renu; Yadav, Gitanjali
Plant genomes can withstand small- and large-scale duplications, at a far greater success than any other kingdom in the tree of life, resulting in the existence and evolution of gene families, often with over a hundred members! The gene families, in turn, go through subfunctionalization or neofunctionalization, to form protein domains performing unique or grouped functions in context of the original activity. Due to the large number of such cases in the plant kingdom, it has become a routine task for plant biologists to investigate their specific gene family of interest. In this chapter, we provide a simple and standard pipeline for this effort, taking the example of steroidogenic acute regulatory protein (StAR) related lipid transfer (START) domains in rice, as reference. We describe the extraction, processing, and downstream analysis of Oryza sativa var. japonica proteome towards identification and comparative exploration of START domains. This was done by training profile Hidden Markov Models (HMM) of 35 reported START domains in Arabidopsis, which were then used to search potential homologs in rice. Downstream investigations included domain structure analysis, visualization of exon–intron patterns, chromosomal localization of START genes, and phylogenetic studies, followed by identification of cis-regulatory elements and gene regulatory network construction. Additionally, we have also highlighted various alternative tools and techniques that can be used to perform similar analyses, along with salient features.
Metabolomics and molecular physiology perspective for drought and salinity stress tolerance
(Taylor & Francis Group, 2022) Jadhav, Sagar Sudam; Kumari, Renu; Mahtha, Sanjeet Kumar; Purama, Ravi Kiran; Lamba, Vinita; Yadav, Gitanjali
Among abiotic stresses, drought and salinity are mainly affecting crop production. Reactive oxygen species are produced during most of abiotic stresses and can damage cellular components. Therefore, plants produce specific antioxidants (e.g. carotenoids, xanthophylls), metabolites (e.g. flavonoids, phenols), osmoregulatory solutes (e.g. proline, sucrose) and thylakoid stabilizing isoprenes. Plant metabolic networks are complex, and excessive demand for these stress-responsive metabolites during abiotic stress is met only by reconfiguring the metabolic network. This chapter mainly discusses drought and salt stress-specific plant metabolomic and molecular responses and gives insights into signaling network involved thereof. Metabolomics combined with conventional breeding approaches (using introgression lines) has proven to be able to map abiotic stress-responsive loci and key candidates. The role of kinases and argonautes and the prospecting of stress-responsive metabolic quantitative trait loci and alleles are also discussed. The importance of amino acid and hormone metabolism and its connection with epigenetics is reviewed.
StAR-related lipid transfer (START) domains across the rice pangenome reveal how ontogeny recapitulated selection pressures during rice domestication
(Frontiers Media S.A., 2021) Mahtha, Sanjeet Kumar; Purama, Ravi Kiran; Yadav, Gitanjali
The StAR-related lipid transfer (START) domain containing proteins or START proteins, encoded by a plant amplified family of evolutionary conserved genes, play important roles in lipid binding, transport, signaling, and modulation of transcriptional activity in the plant kingdom, but there is limited information on their evolution, duplication, and associated sub- or neo-functionalization. Here we perform a comprehensive investigation of this family across the rice pangenome, using 10 wild and cultivated varieties. Conservation of START domains across all 10 rice genomes suggests low dispensability and critical functional roles for this family, further supported by chromosomal mapping, duplication and domain structure patterns. Analysis of synteny highlights a preponderance of segmental and dispersed duplication among STARTs, while transcriptomic investigation of the main cultivated variety Oryza sativa var. japonica reveals sub-functionalization amongst genes family members in terms of preferential expression across various developmental stages and anatomical parts, such as flowering. Ka/Ks ratios confirmed strong negative/purifying selection on START family evolution, implying that ontogeny recapitulated selection pressures during rice domestication. Our findings provide evidence for high conservation of START genes across rice varieties in numbers, as well as in their stringent regulation of Ka/Ks ratio, and showed strong functional dependency of plants on START proteins for their growth and reproductive development. We believe that our findings advance the limited knowledge about plant START domain diversity and evolution, and pave the way for more detailed assessment of individual structural classes of START proteins among plants and their domain specific substrate preferences, to complement existing studies in animals and yeast.