Ph.D. Program in Plant Molecular Biology

Friday Seminar by Ms. Barkha Ravi

GKP Lab/ Friday/ November 30, 2018/ 3.30 pm/ Suppressor screening via EMS Mutagenesis : Illuminating novel key regulators in stress signalling pathways.
Category: Research

Suppressor Screening via EMS Mutagenesis : Illuminating novel key regulators in Stress Signaling pathways.


Plant undergoes continuous exposure to various biotic and abiotic stresses in their natural environment which contributes to the reduction of plant yield. Due to involvement in intricate and complex mechanisms of perception, transduction, and transmission of stress stimuli, they respond optimal to environmental conditions. Therefore it is crucial to understand the mechanisms of plant stress signaling. A powerful approach for determining the biological functions of genes in an organism is to produce mutants with altered phenotypes and physiological responses. Various approaches for mutagenesis involving chemical, irradiation, and insertional methods have been developed. In this post-genomic era, the use of reverse genetic approaches to understanding the role of genes in growth and development has become widespread but with development of new techniques deconvoluting the same has been more convenient. Forward genetic screens are developed by inducing mutagenesis in organisms with well defined genetic background followed by identification of interesting mutant phenotype. Specifically a suppressor screen is used to identify suppressor mutation which revert the phenotype of the original mutation and are extremely useful to define the functions of biochemical pathways within a cell and the relationships between different biochemical pathways. There are various approaches for mutagenesis involving chemical, irradiation, and insertion methods have been developed. Among the chemical mutagens, ethyl methanesulfonate (EMS) is considered as an effective one because it can from adducts with nucleotides efficiently, resulting in mispairing among these nucleotides with their complementary bases and thus introducing base changes after replication. With time utilizing this approach several novel components in major signaling events are been unmasked. Mineral nutrients play a critical role in plant stress resistance. As one of the essential macronutrients, potassium (K) plays crucial roles in plant development and growth by regulating cell electroneutrality, membrane potential, osmolality and enzyme activity. Suppressor screening of low-K + sensitive [lks1 (cipk23)] revealed the suppressor of lks1 (sls1) mutant, which suppressed the leaf chlorosis phenotype of lks1 under LK conditions to synergistacally modulate AKT1- mediated low potassium stress. Similarly genetic studies on the suppressors (soms) of mosaic death 1 (mod1) in Arabidopsis thaliana which presents an elevated ROS level reveals a comprehensive organelle communication pathway that regulates the generation of mitochondrial ROS and triggers PCD. Brassinosteroids (BRs), the polyhydroxylated steroid hormones of plants, regulate almost every phase of plant growth and development. To date, numerous studies have highlighted BRs-induced stress tolerance to various environmental extremes such as high temperature, chilling, drought, salinity and heavy metals in a range of plant species. However, the in-depth mechanisms of BRs-induced stress tolerance still remain largely unknown. The plant brassinosteroid (BR) receptor, BRASSINOSTEROID INSENSITIVE 1 (BRI1), undergoes constitutive cycling between the plasma membrane and the internal membranes. in Arabidopsis thaliana, of a suppressor of bri1, (sbi1), which caused selective accumulation of BR-activated BRI1 and how this receptor dephosphorylation and degradation thus leads to the termination of BR signaling. In a nut shell Generation of diverse mutant alleles in the same gene using EMS provides critical tools to understand the role of these genes in the function of the organism and With help of automation, robust and rapid detection makes it possible to screen a wide range of mutant pools in a short time and to avoid the often laborious process of forward genetic screening.