Molecular identification of a root apical cell-specific and stress-responsive enhancer from an enhancer trap line.

Background: Plant root apex is the major part to direct the root growth and development by responding to various signals/cues from internal and soil environments. To study and understand root system biology particularly at a molecular and cellular level, an T-DNA insertional enhancer trap line J3411 expressing reporters (GFP) only in the root tip was adopted in this study to isolate a DNA fragment.

Results: Using nested PCR, DNA sequencing and sequence homology search, the T-DNA insertion site(s) and its flanking genes were characterised in J3411 line.

Molecular identification and functional characterization of GhAMT1.3 in ammonium transport with a high affinity from cotton (Gossypium hirsutum L.).

Ammonium (NH ) represents a primary nitrogen source for many plants, its effective transport into and between tissues and further assimilation in cells determine greatly plant nitrogen use efficiency. However, biological components involved in NH movement in woody plants are unclear. Here, we report kinetic evidence for cotton NH uptake and molecular identification of certain NH transporters (AMTs) from cotton (Gossypium hirustum).

The ureide-degrading reactions of purine ring catabolism employ three amidohydrolases and one aminohydrolase in Arabidopsis, soybean, and rice.

Several ureides are intermediates of purine base catabolism, releasing nitrogen from the purine nucleotides for reassimilation into amino acids. In some legumes like soybean (Glycine max), ureides are used for nodule-to-shoot translocation of fixed nitrogen. Four enzymes of Arabidopsis (Arabidopsis thaliana), (1) allantoinase, (2) allantoate amidohydrolase (AAH), (3) ureidoglycine aminohydrolase, and (4) ureidoglycolate amidohydrolase (UAH), catalyze the complete hydrolysis of the ureide allantoin in vitro.

Rice DUR3 mediates high-affinity urea transport and plays an effective role in improvement of urea acquisition and utilization when expressed in Arabidopsis.

• Despite the great agricultural and ecological importance of efficient use of urea-containing nitrogen fertilizers by crops, molecular and physiological identities of urea transport in higher plants have been investigated only in Arabidopsis. • We performed short-time urea-influx assays which have identified a low-affinity and high-affinity (K(m) of 7.55 μM) transport system for urea-uptake by rice roots (Oryza sativa).

Identification and characterization of proteins involved in rice urea and arginine catabolism.

Rice (Oryza sativa) production relies strongly on nitrogen (N) fertilization with urea, but the proteins involved in rice urea metabolism have not yet been characterized. Coding sequences for rice arginase, urease, and the urease accessory proteins D (UreD), F (UreF), and G (UreG) involved in urease activation were identified and cloned. The functionality of urease and the urease accessory proteins was demonstrated by complementing corresponding Arabidopsis (Arabidopsis thaliana) mutants and by multiple transient coexpression of the rice proteins in Nicotiana benthamiana.