Figure 2: GABA regulates Al³⁺-activated malate efflux through TaALMT1.

(a) TaALMT1 expression in barley¹⁰ increases malate efflux and root growth of barley in the presence of 100 μm Al³⁺ at pH 4.5, over 22 h, but this is negatively regulated by 10 μM muscimol (Mus). (b) Representative current traces from TaALMT1-injected X. laevis oocytes voltage-clamped at −120 mV challenged with 100 μm Al³⁺ ± 100 μm GABA or 10 μM muscimol (Mus) at pH 4.5. (c) Malate efflux from TaALMT1-expressing BY2 cells¹¹ in standard BY2 solution at pH 4.5 ± 100 μm Al³⁺ ± 10 μm Mus ± 100 μm bicuculline (Bic). For controls for b and c, see Supplementary Fig. 2. *indicates significant differences between genotypes at P<0.05 using a two-tailed t-test (a) or one-way analysis of variance (c). Full-TaALMT1 sequence identifier (DQ072260). All data n=5 biological replicates (except b, which are representative traces from n=5). All error bars are ±s.e.m. Transgenic barley experiments were repeated twice, Xenopus oocyte experiments were repeated with at least three different frogs and BY2 tobacco cell experiments were repeated thrice.