Submitted to: Plant Physiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/20/2002
Publication Date: 11/1/2002
Citation: WANG, Y., GARVIN, D.F., KOCHIAN, L.V. RAPID INDUCTION OF RESULATORY AND TRANSPORTER GENES IN RESPONSE TO PHOSPHORUS, POTASSIUM NAD IRON DEFICIENCIES IN TOMATO ROOTS. EVIDENCE FOR CROSS TALK AND ROUT/RHIZOSPHERE-MEDIATED SIGNALS. PLANT PHYSIOLOGY. 2002. v. 130. p. 1361-1370. Interpretive Summary: Mineral nutrient fertilizer inputs are a major cost for agriculture as mineral deficiencies limit crop production on many soils worldwide. There are also negative environmental consequences for the extensive use of fertilizers in crop production, as fertilizer not absorbed by crop plants can subsequently leach into and contaminate water supplies. Therefore, it would be desirable to develop strategies to reduce fertilizer input while simultaneously maintaining productivity. A more complete understanding of the molecular and physiological basis of mineral nutrient uptake and metabolism in plants may reveal strategies for accomplishing these goals. In this study, we employed molecular and genomic approaches involving arraying root genes on nylon membranes to study those genes turned on in tomato roots by imposition of K, P or Fe deficiency. Recovery of genes previously reported to be induced by these mineral deficiencies validated the strategy we used. In addition to these genes, we identified a series of new genes that exhibit inducibility very rapidly after imposition of the specific mineral deficiency, including genes involved in transmitting and transducing signals resulting from environmental stimuli, genes involved in the regulation of other genes, several different mineral transporters genes, and general stress response genes. The identification of these genes is providing new avenues of research into the molecular basis of plant mineral nutrition, including the possible linkages and networking between regulation of K, P, and Fe nutrition, as well as processes and mechanisms by which plants sense and respond to changes in plant mineral status, and the connections between mineral ion transporters and plant metabolic pathways.
Technical Abstract: Mineral nutrient deficiencies constitute major limitations for crop plant growth on agricultural soils around the world. Thus, there is considerable interest in gaining a better understanding of the molecular basis for mineral nutrient acquisition and utilization, in order to develop mineral nutrient-efficient crops better suited for agricultural production with less fertilizer inputs. In this paper, we have employed a genomics approach to identify novel genes involved in P, K, and Fe nutrition with particular interest in candidate genes involved in mineral nutrient homeostasis. We recently generated a high-density array consisting of 1280 mineral nutrition-related genes from tomato roots which was used for gene expression profiling and resulted in the identification of a number of novel nitrate-induced genes that play roles in N nutrition. In the current study, we used the same cDNA array as a preliminary screening tool to identify genes induced by specific mineral nutrient deficiencies (P, K, an Fe). Subsequently, RNA gel blot analysis was used to study the time courses for expression of these genes in response to withholding P, K or Fe. A set of novel genes associated with P, K and Fe nutrition were identified, including genes that could play a role in mineral nutrition signal transduction such as a transcription factor, MAP kinases, and 14-3-3 proteins, as well as ion transporters, genes involved in plant metabolism and several genes with unknown functions.