|ZHOU, S. - Tennessee State University
|OKEKEOGBU, I. - Tennessee State University
|SANGIREDDY, S. - Tennessee State University
|YI, Z. - Tennessee State University
|HUI, L. - Tennessee State University
|BHATTI, S. - Tennessee State University
|HUI, D. - Tennessee State University
|Thannhauser, Theodore - Ted
Submitted to: Journal of Proteome Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2016
Publication Date: 5/6/2016
Citation: Zhou, S., Okekeogbu, I., Sangireddy, S., Yi, Z., Hui, L., Bhatti, S., Hui, D., Yang, Y., Howe, K.J., Fish, T., Thannhauser, T.W. 2016. Proteome modification in tomato plants upon long-term aluminum treatment. Journal of Proteome Research. 15:1670-1684.
Interpretive Summary: Aluminum toxicity on acidic soils represents a significant limitation to production for many important crop species including tomato. Thus, efforts to gain an understanding of the cellular process that are associated with Al toxicity and tolerance are critical. The information gained can be used to breed or engineer crop varieties with traits that allow them to endure higher aluminum concentrations allowing them to be grown on what is now considered “marginal soils.” Here we use a stable isotope coded labeling strategy to evaluate the long term impact of sub-lethal concentrations Al3+ at pH 4.5 on protein expression in various tissue types including root, leaf, embryo and seed coat. The changes in protein expression in roots were found to be associated with Al3+ uptake, transportation and other cellular processes whereas the protein expression changes in the leaf tissue involved the photosynthetic machinery. The embryo and seed coats of the Al3+ treated plants were enriched in stress related proteins. The changes in protein expression were consistent with the observed changes in morphology of the plants and thus they provide insights into the molecular mechanisms associated with Al3+ tolerance in tomato.
Technical Abstract: This study aimed to identify the aluminum (Al)-induced proteomes in tomato (Solanum lycopersicum, “Micro-Tom”) after long-term exposure to the stress factor. Plants were treated in Magnavaca’s solution (pH 4.5) supplemented with 7.5 uM Al3+ ion activity over a 4 month period beginning at the emergence of flower buds and ending when the lower mature leaves started to turn yellow. Proteomes were identified using 8-plex isobaric tags for relative and absolute quantification (iTRAQ) labeling strategy followed by a two-dimensional (high- and low-pH) chromatographic separation and final generation of tandem mass spectrometry (MS/MS) spectra of tryptic peptides on an LTQ-Orbitrap Elite mass spectrometer. Principal component analysis revealed that the Al-treatment had induced systemic alterations in the proteomes from roots and leaves but not seed tissues. The significantly changed root proteins were shown to have putative functions in Al3+ ion uptake and transportation, root development, and a multitude of other cellular processes. Changes in the leaf proteome indicate that the light reaction centers of photosynthetic machinery are the primary targets of Al-induced stress. Embryo and seed-coat tissues derived from Al-treated plants were enriched with stress proteins. The biological processes involving these Al-induced proteins concur with the physiological and morphological changes, such as the disturbance of mineral homeostasis (higher contents of Al, P, and Fe and reduced contents of S, Zn, and Mn in Al-treated compared to nontreated plants) in roots and smaller sizes of roots and the whole plants. More importantly, the identified significant proteins might represent a molecular mechanism for plants to develop toward establishing the Al tolerance and adaptation mechanism over a long period of stress treatment.