Characterization and Functional Analysis of ZmSWEET15a in Maize

The sugars will eventually be exported transporters (SWEETs) gene family is a new type of sugar transporters, which plays an important role in plant growth and development, physiological metabolism, and abiotic stress. In this study, we used quantitative real-time PCR to analyze the expression of gene in different organs of maize and under different abiotic stresses. The results showed that was expressed in roots, stems, leaves, and grains, with the highest expression level in leaves, which was highly correlated with leaf development. Under the treatment of polyethylene glycol (PEG), NaCl, H O , and abscisic acid stress, the expression of was upregulated, while under the treatment of cold stress, the expression of was inhibited. In sugar-specific experiments, we found that sucrose was the most effective carbon source for maize seed germination. The expression analysis of in different carbon sources suggested that the expression of was more likely to be induced by sucrose. Overexpression of in maize plants could reduce the sucrose content in leaves and increase the sucrose content in grains. The heterologous expression of in the yeast mutant strain SUSY7/ura indicated that is a sucrose transporter and pH independent. This study provides new insight into sugar transport and carbohydrate partitioning in maize and other crops, and provide more genetic information for improving crop quality at the molecular level.