Functional characterization of Citrus macrophylla BOR1 as a boron transporter. Issue 3 (25th March 2013)

• Record Type: Journal Article
• Authors: Cañon, Paola; Aquea, Felipe; Rodríguez‐Hoces de la Guardia, Amparo; Arce‐Johnson, Patricio
• Is Part Of: Physiologia plantarum. Volume 149:Issue 3(2013:Nov.)
• Page Start: 329
• Page End: 339
• Publication Date: 2013-03-25
• Subjects: Plant physiology -- Periodicals; 571.2
• DOI: 10.1111/ppl.12037
• Languages: English
• ISSNs: 0031-9317

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Plants have evolved to develop an efficient system of boron uptake and transport using a range of efflux carriers named BOR proteins. In this work we isolated and characterized a boron transporter of citrus (<italic>Citrus macrophylla</italic>), which was named <italic>CmBOR1</italic> for its high homology to <italic>AtBOR1</italic>. <italic>CmBOR1</italic> has 4403 bp and 12 exons. Its coding region has 2145 bp and encodes for a protein of 714 amino acids. CmBOR1 possesses the molecular features of BORs such as an anion exchanger domain and the presence of 10 transmembrane domains. Functional analysis in yeast indicated that CmBOR1 has an efflux boron transporter activity, and transformants have increased tolerance to excess boron. <italic>CmBOR1</italic> is expressed in leaves, stem and flowers and shows the greatest accumulation in roots. The transcript accumulation was significantly increased under boron deficiency conditions in shoots. In contrast, the accumulation of the transcript did not change in boron toxicity conditions. Finally, we observed that constitutive expression of <italic>CmBOR1</italic> was able to increase tolerance to boron deficiency conditions in <italic>Arabidopsis thaliana</italic>, suggesting that CmBOR1 is a xylem loading boron transporter. Based on these results, it was determined that <italic>CmBOR1</italic> encodes a boric acid/borate transporter involved in tolerance to boron deficiency in plants.</p> </abstract>