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Sugar is an indispensable source of energy for plant growth and development, and it requires the participation of sugar transporter proteins (STPs) for crossing the hydrophobic barrier in plants. Here, we systematically identified the genes encoding sugar transporters in the genome of maize (Zea maysL.), analyzed their expression patterns under different conditions, and determined their functions in disease resistance. The results showed that the mazie sugar transporter family contained 24 members, all of which were predicted to be distributed on the cell membrane and had a highly conserved transmembrane transport domain. The tissue-specific expression of the maize sugar transporter genes was analyzed, and the expression level of these genes was found to be significantly different in different tissues. The analysis of biotic and abiotic stress data showed that the expression levels of the sugar transporter genes changed significantly under different stress factors. The expression levels of ZmSTP2and ZmSTP20continued to increase following Fusarium graminearuminfection. By performing disease resistance analysis of zmstp2and zmstp20mutants, we found that after inoculation with Cochliobolus carbonum, Setosphaeria turcica, Cochliobolus heterostrophus, and F. graminearum, the lesion area of the mutants was significantly higher than that of the wild-type B73 plant. In this study, the genes encoding sugar transporters in maize were systematically identified and analyzed at the whole genome level. The expression patterns of the sugar transporter-encoding genes in different tissues of maize and under biotic and abiotic stresses were revealed, which laid an important theoretical foundation for further elucidation of their functions.

Botrytis cinereais a typical necrotrophic pathogenic fungus that causes severe diseases in a wide range of plant species, leading to significant economic losses. Our previous study showed that BcSDR1positively regulates growth, development, and pathogenicity of B. cinerea. However, the regulation mechanism of BcSDR1and the relationship between BcSDR1and cAMP and MAPK signaling pathways are not well understood. In this study, transcriptome data showed that BcSDR1is involved in glucose transmembrane transport, signal transduction, secondary metabolism, and other biological processes. BcSDR1mutant (BCt41) showed remarkably weak sensitivity to cAMP and MAPK signaling pathways specific inhibitors, SQ22536 and U0126, and significantly decreased cAMP content. The key genes of cAMP and MAPK signaling pathways, BcGB1, BcBTP1, BcBOS1, BcRAS1, and BcBMP3were significantly upregulated, whereas BcPLC1, BcBCG1, BcCDC4, BcSAK1, BcATF1, and BcBAP1were significantly downregulated (P<0.05). BcSDR1was obviously upregulated in BcBCG2, BcBCG3, BcPKA1, and BcPKARRNA interference (RNAi) mutants, but significantly downregulated in BcPKA2, BcBMP1, and BcBMP3RNAi mutants. Thus, BcBCG2, BcBCG3, BcPKA1, and BcPKARnegatively regulate BcSDR1expression, whereas BcPKA2, BcBMP1, and BcBMP3positively regulate BcSDR1expression.