*2.4. Chromosomal Distribution of the UGlcAE Genes in Tomato*

To characterize the distribution of *UGlcAE* genes in the tomato genome, the physical locations of *UGlcAE* genes on the tomato chromosomes were obtained. According to the genomic sequences of *UGlcAE* genes, nine *SlUGlcAE* genes were mapped to eight chromosomes, including chromosome 1, 3, 5, 7, 8, 9, 10, and 12 without regularities of tandem duplication, whose positions were indicated *2.4. Chromosomal Distribution of the UGlcAE Genes in Tomato*

by the black lines in the tomato chromosomes (Figure 3). Two *UGlcAE* genes (*SlUGlcAE3-like1* and *SlUGlcAE6-like*) were located on chromosome 5, and the other seven genes (*SlUGlcAE1*, *SlUGlcAE1-like*, *SlUGlcAE2-like*, *SlUGlcAE3*, *SlUGlcAE3-like2*, *SlUGlcAE5*, and *SlUGlcAE6*) were assigned to different chromosomes, but no gene was mapped to chromosome 2, 4, 6, and 11. There were no tandem duplication events among *UGlcAE* family members of tomato, suggesting that the functional differentiation may exist among the *SlUGlcAE* family members. Almost all of the *UGlcAE* genes in tomato are located near the ends of the chromosome. the black lines in the tomato chromosomes (Figure 3). Two *UGlcAE* genes (*SlUGlcAE3-like1* and *SlUGlcAE6-like*) were located on chromosome 5, and the other seven genes (*SlUGlcAE1*, *SlUGlcAE1-like*, *SlUGlcAE2-like*, *SlUGlcAE3*, *SlUGlcAE3-like2*, *SlUGlcAE5*, and *SlUGlcAE6*) were assigned to different chromosomes, but no gene was mapped to chromosome 2, 4, 6, and 11. There were no tandem duplication events among *UGlcAE* family members of tomato, suggesting that the functional differentiation may exist among the *SlUGlcAE* family members. Almost all of the *UGlcAE* genes in tomato are located near the ends of the chromosome.

3, 5, 7, 8, 9, 10, and 12 without regularities of tandem duplication, whose positions were indicated by

*Int. J. Mol. Sci.* **2018**, *19*, x FOR PEER REVIEW 6 of 21

To characterize the distribution of *UGlcAE* genes in the tomato genome, the physical locations

**Figure 3.** Chromosomal localization of the UGlcAE family genes in tomato. The numbers above each chromosome indicates the chromosome number. **Figure 3.** Chromosomal localization of the UGlcAE family genes in tomato. The numbers above each chromosome indicates the chromosome number.

#### *2.5. Sequence Alignments and Hydrophilicity Analysis of SlUGlcAE Family 2.5. Sequence Alignments and Hydrophilicity Analysis of SlUGlcAE Family*

UGlcAE is one of the short-chain dehydrogenase/reductase (SDR) enzyme families, and therefore the amino acid sequences of SlUGlcAE and AtUGlcAE contained two conserved motifs that existed in SDR protein families [30,31]. As shown in Figure 4, the two motifs contain an N-terminal GxxGxxG (x represents any amino acid) sequence to bind to NAD (P)+, and a motif (YxxxK), which play a catalytic role [32]. UGlcAE is one of the short-chain dehydrogenase/reductase (SDR) enzyme families, and therefore the amino acid sequences of SlUGlcAE and AtUGlcAE contained two conserved motifs that existed in SDR protein families [30,31]. As shown in Figure 4, the two motifs contain an N-terminal GxxGxxG (x represents any amino acid) sequence to bind to NAD (P)<sup>+</sup> , and a motif (YxxxK), which play a catalytic role [32].

As indicated in Supplementary Materials Figure S1, all of the SlUGlcAE proteins were trans-membrane proteins. The result was consistent with previous reports [13,14,24]. Among the nine proteins, most of SlUGlcAEs had only one trans-membrane helice with more than 80% probability, except that SlUGlcAE1 and SlUGlcAE5 were more likely to contain two trans-membrane helices. As indicated in Supplementary Materials Figure S1, all of the SlUGlcAE proteins were trans-membrane proteins. The result was consistent with previous reports [13,14,24]. Among the nine proteins, most of SlUGlcAEs had only one trans-membrane helice with more than 80% probability, except that SlUGlcAE1 and SlUGlcAE5 were more likely to contain two trans-membrane helices.
