Biology subjects

Tripathi, A. M.

Publications and source records attributed to Tripathi, A. M..

3 recordsLinked to original sources

bioRxiv2021

Unraveling the regulatory role of miRNAs responsible for proanthocyanidin biosynthesis in the underutilized legume Psophocarpus tetragonolobus (L.) DC.

The underutilized legume winged bean (Psophocarpus tetragonolobus (L.) DC.) is deposited with various degrees of proanathocyanidin (PA) or condensed tannin (CT) on its seed-coat. PA content of two different lines of P. tetragonolobus was estimated and accordingly they were denoted as high-proanthocyanidin containing winged bean (HPW) and low-proanthocyanidin containing winged bean (LPW). The level of PA-content varied as 59.23 mg/g in HPW and 8.68 mg/g in LPW when estimated through vanillin-HCl assay. The identification and quantification of catechin and epigallocatechin gallate were estimated in a range of 63.8 mg/g and 2.3mg/g respectively in HPW whereas only epigallocatechin gallate was reported in LPW line with a value of 3 mg/g. A comparative miRNA profiling of the leaf-tissues of these contrasting lines of P. tetragonolobus revealed a total of 139 mature miRNAs. Isoforms of known novel miRNAs were also identified in this study. Differentially expressed miRNAs e.g., miR156, miR396, miR4414b, miR4416c, miR894, miR2111 and miR5139 were validated through qRT-PCR analysis. Target prediction of the identified miRNAs especially miR156, miR396, miR4416b shows that they have a potential role in the proanthocyanidin biosynthesis of P. tetragonolobus. The study will provide the basis for understanding the role of miRNAs in regulating the biosynthesis of proanthocyanidin.

genomics↗

bioRxiv2021

Abolished miR158 activity leads to 21-nucleotide tertiary phasiRNA biogenesis that targets NHX2 in Arabidopsis thaliana

Small RNAs including microRNAs (miRNAs) are short 20-24-nucleotide non-coding RNAs. They are key regulators of gene expression in plants and other organisms. Some small RNAs, mostly 22-nucleotide long trigger biogenesis of secondary small interfering RNAs (siRNAs). Those siRNAs having distinctive phased configuration are known as phased siRNAs (phasiRNAs) and act either in cis or trans enhancing silencing cascade. Here, we report natural variants of MIR158 having deletions or insertions led to negligible or reduced expression of miR158. The deletion/insertion events affected processing of primary transcript of miR158 to precursor and to mature miR158. We show that miR158 targets a pseudo-pentatricopeptide gene and its abolished activity led to 21-nucleotide tertiary phasiRNA generation from its target. The biogenesis of these phasiRNAS is triggered by TAS2 derived two siRNAs. Accordingly, small RNA analyses of these natural variants, mutants and over-expression lines of MIR158 or its target exhibited enhanced or reduced phasiRNA biogenesis. Finally, we functionally validated the highest expressed tertiary phasiRNA that targets NHX2 thereby regulating transpiration and stomatal conductance. Overall, we deciphered a new module of small RNA network, miRNA-TAS-siRNA-pseudogene-tertiary phasiRNA-NHX2, suggesting an additional layer of gene regulation and larger role of pseudogene in plants.

plant biology↗

bioRxiv2020

Functional characterization of a "plant-like" HYL1 homolog in the cnidarian Nematostella vectensis indicates a conserved involvement in microRNA biogenesis

While the biogenesis of microRNAs (miRNAs) in both animals and plants depends on the RNase III Dicer, its partner proteins are considered distinct for each kingdom. Nevertheless, recent discovery of homologs of Hyponastic Leaves1 (HYL1), a "plant-specific" Dicer partner, in the metazoan phylum Cnidaria, challenges the view that miRNAs evolved convergently in animals and plants. Here we show that the HYL1 homolog Hyl1-like a (Hyl1La) is crucial for development and miRNA biogenesis in the cnidarian model Nematostella vectensis. Inhibition of Hyl1La by morpholinos resulted in metamorphosis arrest in Nematostella embryos and a significant reduction in levels of most miRNAs. Further, meta-analysis of morphants of miRNA biogenesis components, like Dicer1, shows clustering of their miRNA profiles with Hyl1La morphants. Strikingly, immunoprecipitation of Hyl1La followed by quantitative PCR revealed that in contrast to the plant HYL1, Hyl1La interacts only with precursor miRNAs and not with primary miRNAs. This was complemented by an in vitro binding assay of Hyl1La to synthetic precursor miRNA. Altogether, these results suggest that the last common ancestor of animals and plants carried a HYL1 homolog that took essential part in miRNA biogenesis and indicate early emergence of the miRNA system before plants and animals separated. Impact statementPresence of a functional homolog of HYL1 in Nematostella vectensis, a basal animal model, indicates divergent evolution of miRNA biogenesis pathway in plants and animals from an ancestral miRNA system

evolutionary biology↗