Poster: Nutrient Biology
Abs #
408: Phosphate nutrition effects growth, phosphate transporter expression, and physiology of alfalfa (Medicago sativa L.)
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Presenter: |
Volenec, Jeffrey J., jvolenec@purdue.edu |
Authors | Volenec, Jeffrey J. (A) Abu Qamar, Synan F. (A) Cunningham, Suzanne M. (A) | | Affiliations: |
(A): Purdue University
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Phosphorus (P) deficiency reduces forage yield and stand persistence of alfalfa (Medicago sativa L.). We used suspension cell cultures and a greenhouse study to determine how P-availability influences growth, P-transporter expression, and physiology of alfalfa. Cells were sampled at 3-day intervals for 9 days while growing in media containing 0 to 10 mM P concentrations. Media P concentrations declined rapidly in all P treatments by Day 6, but in 0 and 0.1 mM P treatments, increased significantly by Day 9 as cells excreted P. Low media P concentrations (0, 0.1 and 0.5 mM) reduced cell growth rates when compared to high media P levels (2.5, 5.0 and 10 mM). Suspension cell cultures supplied 0.5, 2.5, 5.0 and 10.0 mM P had lower starch concentrations by Day 3 when compared to cells cultured in media containing 0 and 0.1 mM P. Proteins and amino acids accumulated in cells under the slow growth conditions caused by low media P levels. In the greenhouse study, P-deprived plants were provided 0, 0.5, 2, and 6 mM P seven days before shoot removal (designated as Day 0). Plants were sampled immediately (Day -7) and on Days -5, -2, 0, 1, 2, 6, and 9. In order to characterize tissue-specific expression of P-transporters, roots were separated into bark, wood and fine roots, stem and leaf tissues were collected, and all were analyzed for P concentrations and P-transporter expression. The bark and wood tissues were analyzed for starch and sugar content, amino-N concentration, total protein, and, using SDS-PAGE, changes in vegetative storage protein levels in order to understand P-induced growth responses of alfalfa. Addition of P stimulated growth in P-deficient plants and increased utilization of starch from bark and wood tissues.
