Publications of NIPGR Scientists

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Author: search.filters.author.Tyagi, Akhilesh K.Subject: search.filters.subject.grain

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    Zinc finger transcriptional repressor ZOS5-09 regulates grain filling and development in rice
    (John Wiley & Sons, 2025) Jaiswal, Priya; Qasim, Falah; Mahto, Arunima; Vichitra, Ankur; Das, Upasana; Tyagi, Akhilesh K.; Agarwal, Pinky
    Grain size is one of the key determinants of grain yield. Our study focuses on a novel seed-preferential C2H2 zinc finger transcription factor, ZOS5-09 (LOC_Os05g38600) that plays an important role in regulating rice grain traits. Rice plants with the ZOS5-09 promoter::GUS construct showed high expression of ZOS5-09 in rice endosperm. In planta reporter effector assays and localization studies showed that ZOS5-09 is a nuclear-localized transcriptional repressor. It has two C2H2 zinc finger domains and a C-terminal NoRS (nucleolar retention signal). Ectopic and seed-preferential overexpression of ZOS5-09 resulted in lethality. Seed-preferential overexpression without NoRS was detrimental to grain filling. Rice plants with knock-down or CRISPR-based knock-out of ZOS5-09 displayed reduced grain length and weight but increased grain width. Grain size change was due to lower cell proliferation and increased cell size in the transverse direction because of downregulation of cell cycle-related genes and increased expression of expansins. Decreased expression of ZOS5-09 also resulted in reduced total starch and protein content and higher endosperm chalkiness, thus negatively affecting grain quality. ZOS5-09 directly bound to a zinc finger–binding site and regulated a seed storage protein-encoding gene, GLU6. It acted as a repressor by promoting deacetylation upon interaction with a histone deacetylase. In summary, our results indicate that an optimum expression of ZOS5-09 is essential for proper rice grain development. Our study highlights the role of a transcriptional repressor in regulating rice grain traits and improves our understanding of the transcriptional regulatory networks affecting grain size.
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    OsMED14_2, a tail module subunit of mediator complex, controls rice development and involves jasmonic acid
    (Elsevier B.V., 2024) Prusty, Ankita; Mehra, Poonam; Sharma, Shivam; Malik, Naveen; Agarwal, Pinky; Parida, Swarup K.; Kapoor, Sanjay; Tyagi, Akhilesh K.
    The Mediator complex is essential for eukaryotic transcription, yet its role and the function of its individual subunits in plants, especially in rice, remain poorly understood. Here, we investigate the function of OsMED14_2, a subunit of the Mediator tail module, in rice development. Overexpression and knockout of OsMED14_2 resulted in notable changes in panicle morphology and grain size. Microscopic analysis revealed impact of overexpression on pollen maturation, reflected by reduced viability, irregular shapes, and aberrant intine development. OsMED14_2 was found to interact with proteins involved in pollen development, namely, OsMADS62, OsMADS63 and OsMADS68, and its overexpression negatively affected the expression of OsMADS68 and the expression of other genes involved in intine development, including OsCAP1, OsGCD1, OsRIP1, and OsCPK29. Additionally, we found that OsMED14_2 overexpression influences jasmonic acid (JA) homeostasis, affecting bioactive JA levels, and expression of OsJAZ genes. Our data suggest OsMED14_2 may act as a regulator of JA-responsive genes through its interactions with OsHDAC6 and OsJAZ repressors. These findings contribute to better understanding of the Mediator complex's role in plant traits regulation.