Browsing by Author "Mittal, Lavanya"

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Finding a breather for Oryza sativa: Understanding hormone signalling pathways involved in rice plants to submergence stress
(John Wiley & Sons, 2022) Mittal, Lavanya; Tayyeba, Sumaira; Sinha, Alok Krishna
During the course of evolution, different ecotypes of rice (Oryza sativa L.) have evolved distinct strategies to cope with submergence stress. Such contrasting responses are mediated by plant hormones that are principle regulators of growth, development and responses to various biotic and abiotic stresses. These hormones act cooperatively and show extensive crosstalk which is mediated by key regulatory genes that serve as nodes of molecular communication. The presence or absence of such genes leads to significant changes in hormone signalling pathways and hence, governs the type of response that the plant will exhibit. As flooding is one of the leading causes of crop loss across all the major rice-producing countries, it is crucial to deeply understand the molecular nexus governing the response to submergence to produce flood resilient varieties. This review focuses on the hormonal signalling pathways that mediate two contrasting responses of the rice plant to submergence stress namely, rapid internode elongation to escape flood waters and quiescence response that enables the plant to survive under complete submergence. The significance of several key genes such as Sub1A-1, SLR1, SD1 and SK1/SK2, in defining the ultimate response to submergence has also been discussed.
MPK4-mediated phosphorylation of PHYTOCHROME INTERACTING FACTOR4 controls thermosensing by regulating histone variant H2A.Z deposition
(Oxford University Press, 2024) Verma, Neetu; Singh, Dhanraj; Mittal, Lavanya; Banerjee, Gopal; Noryang, Stanzin; Sinha, Alok Krishna
Plants can perceive a slight upsurge in ambient temperature and respond by undergoing morphological changes, such as elongated hypocotyls and early flowering. The dynamic functioning of PHYTOCHROME INTERACTING FACTOR4 (PIF4) in thermomorphogenesis is well established, although the complete regulatory pathway involved in thermosensing remains elusive. We establish that an increase in temperature from 22˚C to 28˚C induces upregulation and activation of MITOGEN-ACTIVATED PROTEIN KINASE 4 (MPK4) in Arabidopsis (Arabidopsis thaliana), subsequently leading to the phosphorylation of PIF4. Phosphorylated PIF4 represses the expression of ACTIN-RELATED PROTEIN 6 (ARP6), which is required for mediating the deposition of histone variant H2A.Z at its target loci. Furthermore, we demonstrate that variations in ARP6 expression in PIF4 phosphor-null and phosphor-mimetic seedlings affect hypocotyl growth at 22˚C and 28˚C by modulating the regulation of ARP6-mediated H2A.Z deposition at the loci of genes involved in elongating hypocotyl cells. Interestingly, the expression of MPK4 is also controlled by H2A.Z deposition in a temperature-dependent manner. Taken together, these findings highlight the regulatory mechanism of thermosensing by which MPK4-mediated phosphorylation of PIF4 affects ARP6-mediated H2A.Z deposition at the genes involved in hypocotyl cell elongation.
Transcriptomic and OsWAK24-MPK3 crosstalk reveal resistance mechanism of primed rice seedlings against Arsenic-Iron
(Oxford University Press, 2026) Bhatia, Priyanka; Mittal, Lavanya; Pandey, Shubhangi; Khatoon, Narjis Saba; Sinha, Alok Krishna; Gupta, Meetu
Priming, elucidated as "memory," refers to the preconditioning of plant's stress responses to enhance resilience toward future stressors, including arsenic (As) contamination. This adaptive preparedness becomes further complex under As-Fe(iron) interplay, which remains scarcely delineated within priming background. Here, we employed Illumina sequencing to acquire global transcriptome alterations and heterologous interaction approach to chart the molecular reprogramming associated with As and As-Fe-dynamics in primed rice. The transcriptome revealed 3005 and 3650 genes to be differentially regulated in As and As-Fe-exposed primed seedlings. Comprehensive elucidation of expression profiling revealed that key genes were involved in transportation (OsNramp, OsFCR, OsNAS), signalling (OsWRKY, OsMYB, OsAP2, OsZF-TF), and defence (OsHSP, OsPRX, OsCyt P450). The antioxidant (OsGST, OsAPX) expression correlated well with their respective physiological enzyme activity. The entire WAK module, transducing extracellular signals to intercellular pathways, was differentially regulated under As and As-Fe influence. Notably, OsWAK24 revealed higher expression under As-Fe, reflecting its association with seedlings' tolerance behaviour. The computational protein network and docking unfolded OsMPK3 as an interactor of OsWAK24. The split-ubiquitin-based yeast-hybrid assay and immunoblot revealed OsWAK24-OsMPK3 association, suggesting OsMPK3 phosphorylates OsWAK24 at serine residue. Overall, the results decoded the seedling's resilience mechanism and aid in developing rice varieties with desired traits.