Submitted to: American Society of Plant Physiologists Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/29/1999
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: When grown under phosphorus deficient conditions (-P), white lupin (Lupinus albus L.) forms an increased number of short, densely clustered, lateral roots. These cluster or proteoid roots have higher rates of non- photosynthetic carbon fixation and altered metabolism that supports increased levels of organic acid exudation. This adaptation serves to enhance P solubilization and increases P availability to the plant. Recen findings indicate that proteoid roots possess an additional adaptation for increasing P availability. Roots from -P plants have significantly higher acid phosphatase (APase) activity in both intracellular samples and in root exudates. Native-PAGE revealed that under P-deficient conditions, a unique isoform of APase was induced between 10 and 12 days after emergence (DAE). This unique -P induced APase is exuded into the rhizosphere of proteoid root zones. Although this form was found in normal roots, it comprised the emajor form in proteoid roots of -P plants. A PCR product was generated using primers against conserved regions of other excreted and purple acid phosphatases. RNA blot analysis indicates that expression was observed in -P normal roots and was dramatically induced in -P proteoid roots at 14 DAE. No APase transcript was observed in +P normal or +P proteoid roots. Among various other nutritional stress treatments tested, only the presence of aluminum caused a significant induction of APase gene expression in proteoid roots. This research was supported by USDA-NRI grant number 98- 35100-6098.