Plant Physiol, November 2002, Vol. 130, pp. 1361-1370
Rapid Induction of Regulatory and Transporter Genes in
Response to Phosphorus, Potassium, and Iron Deficiencies in Tomato
Roots. Evidence for Cross Talk and Root/Rhizosphere-Mediated
Signals1
Yi-Hong
Wang,
David F.
Garvin, and
Leon V.
Kochian*
United States Plant, Soil, and Nutrition Laboratory, United States
Department of Agriculture-Agricultural Research Service, Cornell
University, Tower Road, Ithaca, New York 14853 (Y.-H.W., L.V.K.); and
Plant Science Research Unit, United States Department of
Agriculture-Agricultural Research Service, 411 Borlaug Hall, University
of Minnesota, St. Paul, Minnesota 55108 (D.F.G.)
Mineral nutrient deficiencies constitute major limitations for
plant growth on agricultural soils around the world. To identify genes
that possibly play roles in plant mineral nutrition, we recently
generated a high-density array consisting of 1,280 genes from tomato
(Lycopersicon esculentum) roots for expression profiling in nitrogen (N) nutrition. In the current study, we used the
same array to search for genes induced by phosphorus (P), potassium (K+), and iron (Fe) deficiencies. RNA gel-blot analysis was
conducted to study the time-dependent kinetics for expression of these
genes in response to withholding P, K, or Fe. Genes previously not
associated with P, K, and Fe nutrition were identified, such as
transcription factor, mitogen-activated protein (MAP) kinase, MAP
kinase kinase, and 14-3-3 proteins. Many of these genes were induced
within 1 h after withholding the specific nutrient from roots of
intact plants; thus, RNA gel-blot analysis was repeated for specific genes (transcription factor and MAP kinase) in roots of decapitated plants to investigate the tissue-specific location of the signal triggering gene induction. Both genes were induced just as rapidly in
decapitated plants, suggesting that the rapid response to the absence
of P, K, or Fe in the root-bathing medium is triggered either by a
root-localized signal or because of root sensing of the mineral
environment surrounding the roots. We also show that expression of Pi,
K, and Fe transporter genes were up-regulated by all three treatments,
suggesting coordination and coregulation of the uptake of these three
essential mineral nutrients.
1
This work was supported by the Agricultural
Research Service Agricultural Genome Program (to L.V.K. and
D.F.G.).
*
Corresponding author; e-mail Lvk1{at}cornell.edu; fax
607-255-2459.
© 2002 American Society of Plant Biologists
