The Arabidopsis Major Intrinsic Protein NIP5;1 Is Essential for Efficient Boron Uptake and Plant Development under Boron Limitation

Abstract

Boron (B) is essential in plants but often present at low concentrations in the environment. To investigate how plants survive under conditions of B limitation, we conducted a transcriptome analysis and identified NIP5;1, a member of the major intrinsic protein family, as a gene upregulated in B-deficient roots of Arabidopsis thaliana. Promoter-b-glucuronidase fusions indicated that NIP5;1 is strongly upregulated in the root elongation zone and the root hair zone under B limitation, and green fluorescent protein-tagged NIP5;1 proteins localized to the plasma membrane. Expression in Xenopus laevis oocytes demonstrated that NIP5;1 facilitated the transport of boric acid in addition to water. Importantly, two T-DNA insertion lines of NIP5;1 displayed lower boric acid uptake into roots, lower biomass production, and increased sensitivity of root and shoot development to B deficiency. These results identify NIP5;1 as a major plasma membrane boric acid channel crucial for the B uptake required for plant growth and development under B limitation.

Boron toxicity tolerance in wheat and barley: Australian perspectives

“…Our data confirm the predictions of the model, showing that HvNIP2;1 can transport a number of metalloids. Given that there is also a role for NIP aquaporins in the acquisition of B under B limiting conditions (Takano et al 2006), it may be of interest to introduce site-specific mutations to HvNIP2;1 to enable discrimination between boric acid and the more toxic arsenous and germanic acid species.…”

“…Arsenite is the predominant form of arsenic (As) in paddy soils. It has previously been suggested that aquaporins may have a role in boron transport in higher plants (Dordas et al 2000, Fitzpatrick and and it was also shown in Arabidposis thaliana that a specific NIP subclass aquaporin gene (AtNIP5;1) is required for normal growth under B limiting conditions (Takano et al 2006, Tanaka et al 2008. NIP5;1 is strongly up-regulated in B-deprived roots and knockout mutants for this gene are defective in low Binducible boric acid uptake into roots (Takano et al 2006).…”

Arabidopsis thaliana NIP7;1 is involved in tissue arsenic distribution and tolerance in response to arsenate

“…Members of the NIP (nodulin-26-like intrinsic proteins) and PIP (plasma membrane intrinsic proteins) subfamilies of aquaporins have been shown to facilitate AsIII transport in plants in Abbreviations NIPs, nodulin-26-like intrinsic proteins; RGR, relative growth rate; WT, wild-type. addition to transporting essential nutrients such as silicon and boron [7][8][9][10][11][12][13].…”

Barley plasma membrane intrinsic proteins (PIP Aquaporins) as water and CO2 transporters

“…Nutritional deficiency in general decreases the expression of Lp and aquaporin genes in roots [4], however, specific genes were induced under special conditions, such as Arabidopsis NIP5;1 by boron-deficiency [24] and Arabidopsis TIP2;1 by nitrogen-deficiency [17]. Low temperature [13], phytohormones [23], and far-red light [22] also regulated the expression of plant aquaporins.…”

“…In the plant genome, more than 30 aquaporin genes have been detected [11,21]. Some of them specifically transport water molecules, but others can mediate other low molecular weight compounds such as CO 2 [7,8,28], silicon [19], boron [24], ammonia [9], and H 2 O 2 [2].…”