Effect of MKT1, SWS2, and APJ1 on ethanol tolerance. (A) The ethanol tolerance of BY4741 (inferior wild type) and the mkt1Δ, sws2Δ, and apj1Δ mutants thereof was determined by scoring growth of twofold dilutions on 10% ethanol after 8 d and 14% ethanol after 12 d. (B) The ethanol tolerance of VR1-5B (superior wild type) and the mkt1Δ, sws2Δ, and apj1Δ mutants thereof was determined by scoring growth of twofold dilutions on 10% ethanol after 6 d and 16% ethanol after 10 d. (C) The VR1-5B allele of MKT1 is beneficial for high ethanol tolerance. MKT1-BY and MKT1-VR, including 534 bp upstream and 344 bp downstream regions of the ORF, were cloned into the low-copy-number plasmid YCplac111 and expressed in BY4741 (BY1) and three segregants from VR1-5B/BY4741 that inherited the MKT1-BY allele (1D, 24A, and 32B). The ethanol tolerance was determined in twofold dilutions on different concentrations of ethanol.
