Premium
Functional characterization of Citrus macrophylla BOR1 as a boron transporter
Author(s) -
Cañon Paola,
Aquea Felipe,
RodríguezHoces de la Guardia Amparo,
ArceJohnson Patricio
Publication year - 2013
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/ppl.12037
Subject(s) - transporter , efflux , xylem , boron , biochemistry , transmembrane domain , arabidopsis , yeast , chemistry , guard cell , amino acid , arabidopsis thaliana , biology , gene , botany , mutant , organic chemistry
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 ( Citrus macrophylla ), which was named CmBOR1 for its high homology to AtBOR1 . CmBOR1 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. CmBOR1 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 CmBOR1 was able to increase tolerance to boron deficiency conditions in Arabidopsis thaliana , suggesting that CmBOR1 is a xylem loading boron transporter. Based on these results, it was determined that CmBOR1 encodes a boric acid/borate transporter involved in tolerance to boron deficiency in plants.