determination-tripartite-interaction-between-two-monomers-mads-box

Determination of Tripartite Interaction between Two Monomers of a MADS-box Transcription Factor and a Calcium Sensor Protein by BiFC-FRET-FLIM Assay

Protein-protein interactions are an integral part of all biological processes in the cells as they play a crucial role in regulating, maintaining, and ...

University of Delhi South Campus

The precisely timed process of tapetum development and its degradation involving programmed cell death is an important molecular event during anther development. Through its degeneration, the tapetum not only provides nutritive substances to the developing microspores but also contributes to the pollen wall by way of sporopollenin, which is a complex mixture of biopolymers, containing long-chain fatty acids, phenylpropanoids, phenolics and traces of carotenoids. A number of dyes and staining methods have been used to visualize tapetal structure and its components by using light microscopy techniques, but none of these methods could differentially stain and thus distinguish tapetal cells from other cell types of anther wall. While analysing progression of tapetum development in different cell types in rice anthers, we discovered a unique property of periodic acid-Schiff (PAS) stain, which upon interaction with some specific component(s) in tapetal cells and developing microspores emits fluorescence at ~620 nm. In rice anthers, the PAS-associated fluorescence could be observed initially in tapetum and developing microspores, and subsequent to degeneration of tapetum, the fluorescence was found to emanate mainly from the pollen wall. We also show that PAS-dependent fluorescence in tapetal cells is distinct from the autofluorescence resulting from pollen wall components and is also not caused by interaction of PAS with pollen starch. Henceforth, this novel fluorescence property of PAS stain could prove to be a new tool in the toolkit of developmental biologists to analyse different aspects of tapetum development and its degeneration with little more ease and specificity.

A novel application of periodic acid-Schiff (PAS) staining and fluorescence imaging for analysing tapetum and microspore development.

In flowering plants, LIKE HETEROCHROMATIN PROTEIN 1 (LHP1)/TERMINAL FLOWER 2 (TFL2) is known to interact with polycomb group (PcG) and non-PcG proteins and control developmental programs. LHP1/TFL2 is an ancient protein and has been characterized in the early-divergent plant Physcomitrella patens. However, interacting partners of PpLHP1 other than the chromomethylase PpCMT have not been identified to date. Also, while functional polycomb repressive complex 2 (PRC2) is known to exist in P. patens, there is no experimental evidence to support the existence of PRC1-like complexes in these mosses. In this study, using protein-protein interaction methods, transient expression assays and targeted gene knockout strategy, we report the conserved properties of LHP1/TFL2 using the Physcomitrella system. We show that a PRC1-like core complex comprising of PpLHP1 and the putative PRC1 Really Interesting New Gene (RING)-finger proteins can form in vivo. Also, the interaction between PpRING and the PRC2 subunit PpCLF further sheds light on the possible existence of combinatorial interactions between the Polycomb Repressive Complex (PRC) in early land plants. Based on the interaction between PpLHP1 and putative hnRNP PpLIF2-like in planta, we propose that the link between PpLHP1 regulation and RNA metabolic processes was established early in plants. The conserved subnuclear distribution pattern of PpLHP1 in moss protonema further provides insight into the manner in which LHP1/TFL2 are sequestered in the nucleoplasm in discrete foci. The PpLHP1 loss-of-function plants generated in this study share some of the pleiotropic defects with multiple aberrations reported in lhp1/tfl2. Taken together, this work documents an active role for PpLHP1 in epigenetic regulatory network in P. patens.

Article	Year
A novel application of periodic acid-Schiff (PAS) staining and fluorescence imaging for analysing tapetum and microspore development. Histochemistry and cell biology\| PubMed ID: 27565968	2017
Functional characterization of LIKE HETEROCHROMATIN PROTEIN 1 in the moss Physcomitrella patens: its conserved protein interactions in land plants. The Plant journal : for cell and molecular biology\| PubMed ID: 30537172	2019

Vibha Verma

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