ABSTRACT
An in-depth understanding of the biology and physiology of the plant root system and its chemical and physical interactions with the surrounding soil environment remains a challenge for scientists, but needs to be elucidated in order to improve crops yields and culturing techniques. Crop yield increases depend on how roots are able to effectively utilize soil to absorb the water and nutrients necessary for plant growth. Many previous root system studies have elucidated mechanisms induced by environmental stress to identify gene products of agronomic relevance using functional genomics. More recently, the use of proteomics-dened as the systematic analysis of the protein population in a tissue, cell, or subcellular compartment-has also shown a large impact on plant biology. Because qualitative and quantitative changes in protein and enzyme patterns are manifestations of the activity of genes controlling the metabolic activity of cells, the interest in proteomics and the number of publications in plant proteomics has increased dramatically over the past 10 years (Figure 10.1). The use of proteomics tools to take snapshots of protein-expression proles of plants has expanded due to the vast improvement of protein gel-and liquid chromatography (LC)-based separation techniques and mass spectrometry instrumentation for protein identication. Furthermore, correlation between gene expression and protein amount and activity is not always straightforward due to posttranscriptional and posttranslational regulation. It has been inferred that 5% of the Arabidopsis thaliana genome encodes kinases and phosphatases, representing over 1000 enzymes
10.4.3 Soil Composition Changes ........................................................................................ 237 10.4.3.1 Salinity Stress ............................................................................................ 237 10.4.3.2 Nitrogen, Potassium, and Phosphorus Deprivation ................................... 238 10.4.3.3 Glycine as a Nitrogen Supply ..................................................................... 239
10.4.4 Metal Contamination-Responsive Proteins ..............................................................240 10.4.4.1 Copper ........................................................................................................240 10.4.4.2 Cadmium .................................................................................................... 241 10.4.4.3 Aluminum ..................................................................................................242 10.4.4.4 Arsenic .......................................................................................................242
