Poster: Mineral nutrition

Abs # 212: Determining the molecular basis of phosphorus efficiency in tropical maize and sorghum genotypes

Presenter:	Vasconcelos, Maria Jose V, vasconcelos@purdue.edu
Authors	Vasconcelos, Maria Jose V (A) (B)  Parentoni, Sidney N (B)   Schaffert, Roberth E (B)   Raghothama, Ragu K G (A)
Affiliations:	(A): Purdue University (B): Embrapa Maize and Sorghum

Phosphate (Pi) deficiency is a major factor limiting crop production in the tropics. Low fertility, low pH, low availability and high fixation of phosphorus and toxic levels of aluminum are characteristics of tropical soils. Strong adsorptions of phosphate to the inner-sphere of soil particles make it hard for plants to obtain. Plant species and even plant cultivars within a species exhibit difference in their ability to utilize adsorbed (fixed) phosphate. The physiological and molecular mechanisms underlying these genetic variations are not thoroughly understood. Previous work at EMBRAPA, Brazil, resulted in development of maize and sorghum genotypes with varied levels of Pi efficiency and responsiveness to applied Pi. It is becoming apparent that Pi efficiency is regulated by coordinated expression of many genes involved in Pi uptake and utilization in plants. These include, but not limited to, phosphate transporters, phosphatases, phytases, citrate synthase and novel genes expressed under phosphate deficiency. In this study the expression of high affinity phosphate transporters in the inbred maize lines and in near isogenic sorghum lines differing in their ability to respond to applied Pi was examined. The Zea mays phosphate transporter clones ZmPTs obtained from Pioneer HiBred Co. were used as probes in Northern blot analysis. The Pi transporters are induced specifically under Pi starvation. The maize probe also hybridized strongly to transcripts in phosphate starved roots of sorghum. Quantitative differences in the transcript abundance were observed among the genotypes. The significance of differences in the level of expression of the high affinity Pi transporters and other genes involved in P starvation in maize and sorghum genotypes will be discussed.