This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: Expression profiles of 10,422 genes at early stage of low nitrogen stress in rice assayed using a cDNA microarray Xingming Lian 1 , Shiping Wang 1 , Jianwei Zhang 1 , Qi Feng 2 , Lida Zhang 1 , Danlin Fan 2 , Xianghua Li 1 , Dejun Yuan 1 , Bin Han 2 and Qifa Zhang 1, * 1 National Key Laboratory of Crop Genetic Improvement, National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China (*author for correspondence; e-mail firstname.lastname@example.org); 2 National Center for Gene Research, Chinese Academy of Sciences, Shanghai 200233, China Received 13 April 2005; accepted in revised form 18 July 2005 Key words: cDNA chip, ESTs, nitrogen use efficiency (NUE), Oryza sativa L. Abstract Development of crop varieties with high nitrogen use eﬃciency (NUE) is imperative for sustainable agri- culture. Understanding how plant genes respond to low N stress is essential for formulating approaches to manipulating genes for improving NUE. In this study we analyzed the expression profiles of an indica rice cultivar Minghui 63 at seedling stage at 20 min, 1 and 2 h after low N stress with the normal N as the control, using a microarray of 11,494 rice ESTs representing 10,422 unique genes. While no significant difference was detected in the leaf tissue, a total of 471 ESTs were detected as responsive to low N stress in the root tissue with 115 ESTs showing up-regulation and 358 ESTs showing down-regulation. The analysis of expression profiles after low N stress identified following patterns: (1) the genes involved in photosyn- thesis and energy metabolism were down-regulated rapidly; (2) many of the genes involved in early responses to biotic and abiotic stresses were up-regulated while many other stress responsive genes were down-regulated; (3) regulatory genes including transcription factors and ones involved in signal trans- duction were both up- and down-regulated; and (4) the genes known to be involved in N uptake and assimilation showed little response to the low N stress. The challenges for future studies are to characterize the functional roles of the low N stress responsive genes in N metabolisms, including the large number of genes presently with unknown functions. Introduction Nitrogen is a crucial plant macronutrient and is needed in the greatest amount of all mineral elements required by plants. It is a constituent of numerous important compounds, including amino acids, proteins (enzymes), nucleic acids, chloro- phyll and several plant hormones. It comprises 1.5–2% of plant dry matter and approximately 16% of total plant protein (Frink et al ., 1999). In the last half a century, the global use of N fertilizer increased 10-folds in order to increase crop productivity (UNEP, 1999), as a consequence of the fact that most of the high yielding varieties of the major crops developed in the last several decades have high demands of N and other nutrients, as well as optimal cultivation conditions....
View Full Document