Because of the importance of the nucleus, the proteomic analysis of nuclear proteins has attracted considerable recent interest and the findings from plant nuclear proteomic studies have been reviewed. To date, the nuclear proteome of many plant species, including Arabidopsis, Medicago, rice, chickpea, tomato, potato, apple, maize, Xerophyta viscosa , hot pepper, barley, wheat and soybean, has been analyzed. Soybean, which is cultivated worldwide, provides an abundant source of protein and edible vegetable oil for human consumption. Although soybean is able to grow in a wide range of climatic conditions, plant growth and grain yield are greatly reduced by flooding, which is typically caused by heavy or continuous rainfall in areas with poorly drained soil. In response to flooding stress, soybean displays altered patterns of gene expression, protein abundance, and metabolite accumulation. To identify the upstream events controlling the regulation of flooding-responsive proteins in soybean, the proteomic analysis of nuclear proteins is a powerful technique.

Proteomic techniques allow for the systematic analysis of complex cellular mechanisms, such as plant responses to abiotic stress, as proteomic analyses provide qualitative and quantitative data on protein properties, including intracellular distribution, turnover dynamics, protein–protein interactions, and post-translational modifications. Determination of the nuclear proteome provides insight into the complex regulatory networks that function in plant nuclei. Recent advances in nuclear proteomic techniques have allowed for the ever-more sensitive detection of nuclear proteins. Using these approaches, nuclear proteins that are modulated in response to flooding stress were extensively characterized in soybean. In the present review, methods for nuclei purification from various plant species are described and common modifications of plant nuclear proteins are presented. Furthermore, to provide insight into the upstream mechanisms regulating the early soybean responses to flooding stress, the functions of flooding-responsive nuclear proteins are discussed. For the purification of plant nuclei, homogenization buffers with variable compositions depending on the type of plant material and intended downstream analysis have been used. The basic requirements for a suitable homogenization buffer are that the integrity of the nuclear membrane and stability of nuclei must be maintained during the isolation of released nuclei from intact cells. Phosphorylation is one of the most studied posttranslational modifications and is a common signaling event that occurs upon plant exposure to abiotic and biotic stresses. Approximately one-third of all eukaryotic proteins are modified by phosphorylation. Jørgensen and Linding reported that the structure, interaction partners, and subcellular localization of proteins were affected by phosphorylation. With the development of effective plant nuclei isolation methods and technological advances in tandem MS, large-scale nuclear proteomic studies have become feasible, Performed a nuclear proteomic study in Arabidopsis using two-dimensional gel electrophoresis (2DE) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) and identified 158 nuclear proteins that were related to signaling and gene regulation. Flooding is an abiotic stress that severely affects crop growth. Soybean is particularly sensitive to flooding stress and exhibits markedly reduced growth under flooding. In response to flooding, numerous soybean proteins related to signal transduction and hormonal signaling, transcriptional control, glucose degradation/sucrose accumulation, alcohol fermentation, suppression of active oxygen scavenging, mitochondrial impairment, ubiquitin/proteasome-mediated proteolysis

Regrads,
Catherine
Journal Co-Ordinator
Annals of Biological Sciences