Publications of NIPGR Scientists

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Author: search.filters.author.Ram, HasthiSubject: search.filters.subject.Functional genomics

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    A CRISPR-Cas9 library to target putative redundant gene sets facilitates their functional exploration in grain development in rice
    (Springer Nature Publishing AG, 2025) Yadav, Banita; Sardar, Shaswati; Yadav, Anil; Kumari, Annapurna; Gautam, Mohini; Mandlik, Rushil; Arora, Simran; Kumar, Shailesh; Jewaria, Pawan Kumar; Sonah, Humira; Deshmukh, Rupesh; Chinnusamy, Viswanathan; Ram, Hasthi
    Advent of CRISPR-Cas9 library approach has revolutionized the field of high throughput targeted mutagenesis in plants. By identifying an sgRNA spacer that can target multiple paralogous genes in a genome, higher-order knockout plants can be developed. Using this concept, we developed ten CRISPR-Cas9 pool libraries and generated higher-order knockout plants in rice. Towards this, firstly we identified genome-wide sets of genes which are co-expressed and have high sequence similarity and can be targeted by a single sgRNA. Based on the expression pattern, these genes were divided into ten groups, and subsequently ten CRISPR-Cas9 plasmid libraries were developed. One such library designed against seed-expressed genes was transformed into rice and higher-order knockout plants were developed. Genotyping revealed that around 90% T0 plants had editing, and among the edited plants majority of them were higher-order knockouts. Phenotypic analysis in the next generation discovered functions of several seed specific genes in grain length, width, number and 100-grain weight. By analyzing single and double mutants for two Agenet domain-containing proteins, we have discovered an epistatic interaction between them for grain development. Further application of our approach will help to uncover hidden functions of the targeted genes and accelerate functional genomics research in rice. The CRISPR-Cas9 library is a useful approach to generate higher-order knockout mutants and identify functions of the targeted genes in rice.
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    Global gene regulatory network underlying miR165a in Arabidopsis shoot apical meristem
    (Springer Nature Publishing AG, 2023) Sinha, Sonali; Sahadevan, Sudeep; Ohno, Carolyn; Ram, Hasthi; Heisler, Marcus G
    Arabidopsis microRNA165a (miR165a) targets Class III Homeodomain Leucine-Zipper (HD-ZIPIII) transcription factors to regulate various aspects of plant development and stress response. Overexpression of miR165a mimics the loss-of-function phenotype of HD-ZIPIII genes and leading to ectopic organ formation, shoot apical meristem (SAM) termination, loss of leaf polarity, and defective vasculature development. However, the molecular mechanisms underlying these phenotypes remain unresolved. Here, we over-expressed miR165a in a dexamethasone inducible manner and identifed diferentially expressed genes in the SAM through RNA-Seq. Simultaneously, using multichannel FACS combined with RNA-Seq approach, we characterized global transcriptome patterns in miR165a expressing cell-types compared to HD-ZIPIII expressing cell-types and other cell-types in SAM. By integrating our results we identifed sets of genes which are up-regulated by miR165a as well have enriched expression in miR165a cell-types, and vice-versa. Known plant development related genes such as HD-ZIPIII and their targets LITTLE ZIPPERs, Like AUXIN RESISTANT 2, BEL1-like homeodomain 6, ROTUNDIFOLIA like 16 were found to be down-regulated. Among the up-regulated genes, GIBBERELLIN 2-OXIDASEs, various elemental transporters (YSL3, ZIFL1, SULTR), and other transporter genes were prominent. Thus, the genes identifed in this study help to unravel the molecular mechanism of miR165a and HD-ZIPIII regulated plant development and stress response.