Location: Plant, Soil and Nutrition ResearchTitle: Effect of aluminum treatment on proteomes of radicles of seeds derived from Al-treated tomato plants) Author
|Thannhauser, Theodore - Ted|
Submitted to: Proteomes
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/4/2014
Publication Date: 3/28/2014
Citation: Okekeogbu, I., Ye, Z., Sangireddy, S.R., Li, H., Bhatti, S., Zhou, S., Howe, K.J., Fish, T., Yang, Y., Thannhauser, T.W. 2014. Effect of aluminum treatment on proteomes of radicles of seeds derived from Al-treated tomato plants. Proteomes. 2(2):169-190. Interpretive Summary: Aluminum toxicity is a major constraint to plant growth and production on acid soils. This study resulted in the surprising observation that tomato plants grown in aluminum enriched, acidic growth media accumulated measurable amounts of aluminum in their seeds. A seed germination assay indicated no significant difference in terms of radicle growth rate between Al-treated and untreated seed groups. These results indicate that radicle elongation growth was not affected by the presence of Al in these seeds. Nevertheless, there were significant changes in protein expression between the Al treated and non-treated seeds during radicle development. Among the proteins whose abundance levels changed significantly were: a number of transcription factors; proteins regulating gene silencing and programmed cell death; proteins in primary and secondary signaling pathways and proteins for enhancing tolerance to abiotic and biotic stress. These results are significant because changes in protein expression as a function of Al treatment can provide insight into mechanisms associated with Al tolerance that can provide testable hypotheses concerning how to improve Al tolerance in this important crop species.
Technical Abstract: Aluminum (Al) toxicity is a major constraint to plant growth and crop yield in acid soils. Tomato cultivars are especially susceptible to excessive A1 3+ accumulated in the root zone. In this study, tomato plants were grown in a hydroponic culture system supplemented with 50 uM AlK(SO4)2. Seeds harvested from Al-treated plants contained a significantly higher Al content than those grown in the controlled hydroponic solution. In this study, these Al-enriched tomato seeds (harvested from Al-treated tomato plants) were germinated in 50 uM AlK(SO4)2 solution in a homopiperazine-1,4-bis(2-ethanesulfonic acid) buffer (pH 4.0), and the control solution which contained the buffer only. Proteomes of radicles were analyzed quantitatively by mass spectrometry employing isobaric tags for relative and absolute quantitation (iTRAQ). The proteins identified were assigned to molecular functional groups and cellular metabolic pathways using MapMan. Among the proteins whose abundance levels changed significantly were: a number of transcription factors; proteins regulating gene silencing and programmed cell death; proteins in primary and secondary signaling pathways, including phytohormone signaling and proteins for enhancing tolerance to abiotic and biotic stress. Among the metabolic pathways, enzymes in glycolysis and fermentation and sucrolytic pathways were repressed. Secondary metabolic pathways including the mevalonate pathway and lignin biosynthesis were induced. Biological reactions in mitochondria seem to be induced due to an increase in the abundance level of mitochondrial ribosomes and enzymes in the TCA cycle, electron transport chains and ATP synthesis.