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Title: Localization of an evolutionarily conserved protein proton pyrophosphatase in evolutionarily distant plants oryza sativa and physcomitrella patens

Author
item REGMI, KAMESH - Arizona State University
item ZHANG, SHANGJI - Arizona State University
item GAXIOLA, ROBERTO - Arizona State University
item HIRSCHI, KENDAL - Children'S Nutrition Research Center (CNRC)

Submitted to: Plant Biology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 6/18/2015
Publication Date: 7/26/2015
Citation: Regmi, K., Zhang, S., Gaxiola, R., Hirschi, K.D. 2015. Localization of an evolutionarily conserved protein proton pyrophosphatase in evolutionarily distant plants oryza sativa and physcomitrella patens [abstract]. Plant Biology Annual Meeting, July 26-30, 2015, Minneapolis, Minnesota. Cell Biology-Zone 700, 700-002-Z, p. 164. Available: http://plantbiology.aspb.org.

Interpretive Summary:

Technical Abstract: Proton Pyrophosphatase (H+-PPase) is a highly evolutionarily conserved protein that is prevalent in the plant kingdom. One of the salient features of H+-PPase expression pattern, at least in vascular plants like Arabidopsis, is its conspicuous localization in both actively dividing cells and the phloem. On one hand, the role of H+-PPase as a Pyrophosphate (PPi) scavenger at the tonoplast of metabolically active cells is well documented. On the other hand, the plasma membrane localization of this protein in the phloem is also recognized, wherein this protein is hypothesized to play a crucial role as a PPi synthase, energizing active sucrose (Suc) loading. Within this wider purview, we have used two evolutionarily distant plants, a vascular monocot Rice and a non-vascular moss Physcomitrella, to analyze the in situ localization patterns of H+-PPase in various tissues of these two model organisms. Were H+-PPases co-opted into a novel functional role in the vascular tissues of higher plants? Or are there evolutionarily conserved roles of this protein that transcend the phylogenetic diversity of land plants? Using light microscopy, we show that H+-PPases are distinctly expressed in the actively growing cells in both Rice and Physcomitrella. As expected, H+-PPases were also localized in the vascular tissues of Rice, but surprisingly, H+-PPases were prominently expressed at the gametophyte-sporophyte junction of Physcomitrella. Upon immunogold labeling, H+-PPases were found to be localized at both the vacuolar and plasma membranes of the sieve element-companion cell complexes of Rice leaves, and transfer cells of the Physcomitrella haustorium.