Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/5/2002
Publication Date: 12/1/2002
Citation: RODRIGUEZ-MILLA, M.A., BUTLER, G.E., RODRIGUEZ-HUETE, A., WILSON, C., ANDERSON, O.D., GUSTAFSON, J.P. EXPRESSED SEQUENCE TAG-BASED GENE EXPRESSION ANALYSIS UNDER ALUMINUM STRESS IN RYE. PLANT PHYSIOLOGY. 2002. v. 130. p. 1706-1716. Interpretive Summary: Aluminum (Al) is one of the most important limiting factors for crop production on acid sols worldwide. There are roughly 3.95 billion hectares of acid soils or about 40% of all arable land in the world. In order to understand the mechanisms responsible for Aluminum (Al) toxicity and tolerance in plants, we utilized an expressed-DNA-sequence-tag approach to analyze changes in gene expression in roots of rye when placed under Al stress. In this manner, we were able to study the response of rye roots when placed in Al. Out of all the genes analyzed, we were able to locate 13 that showed significant levels of increased expression when grown in toxic levels of Al. These genes are currently being studied to provide new insights about rye's response to toxic levels of Al. These new insights should lead scientists to a better understanding of how to improve the ability of wheat, and even rice, to be able to produce a higher yielding crop on soils high in Al.
Technical Abstract: To understand the mechanisms responsible for aluminum (Al) toxicity and tolerance in plants, an 'expressed sequence tag' (EST) approach was used to analyze changes in gene expression in roots of rye under Al stress. Two cDNA libraries were constructed, Al-stressed and unstressed, and a total of 1194 and 774 ESTs were generated, respectively. The putative proteins encoded by these cDNAs were uncoverd by B:ASTX searches. Those ESTs showing similarity to proteins of known function were classified according to 13 different functional categories, providing insights about the structure of the mRNA population in the early stages of Al stress. A total of 671 known-function genes were used to analyze the gene expression patterns in rye root tips under Al stress. Many of the previously identified Al-response genes showed expression differences between the libraries within 6 h of Al stress. Certain genes were selected and their expression profiles were studied during a 48-h period using Northern analysis. A total of 13 novel genes involved in cell elongtion and division (tonoplast aquaporin and ubiquitin-like protein SMT3), oxidative-stress (glutathione peroxidase, glucose-6P-dehydrogenase, and ascorbate peroxidase), iron metabolism (iron deficiency specific proteins IDS3a, IDS3b, and IDS1; s-adenosyl methionine synthase; and methionine synthase), and other cellular mechanisms (pathogenesis-related protein 1.2 heme oxygenase, and epoxide hydrolase) were demonstrated to be regulated by Al stress. These genes provide new insights about the response of Al-tolerant plants to toxic levels of Al.