Plant Physiol 2020 02 26;182(2):992-1006. Epub 2019 Nov 26.
Horticulture Section, School of Integrative Plant Science, Cornell University, Ithaca, New York 14853
Malate accumulation in the vacuole largely determines apple () fruit acidity, and low fruit acidity is strongly associated with truncation of , an ortholog of () in Arabidopsis (). A mutation at base 1,455 in the open reading frame of leads to a premature stop codon that truncates the protein by 84 amino acids at its C-terminal end. Here, we report that both the full-length protein, Ma1, and its naturally occurring truncated protein, ma1, localize to the tonoplast; when expressed in oocytes and cells, Ma1 mediates a malate-dependent inward-rectifying current, whereas the ma1-mediated transmembrane current is much weaker, indicating that ma1 has significantly lower malate transport activity than Ma1. Read More