AUTHOR=Li Yan , Wang Yannan , Zhang Huan , Zhang Qian , Zhai Hong , Liu Qingchang , He Shaozhen 

TITLE=The Plasma Membrane-Localized Sucrose Transporter IbSWEET10 Contributes to the Resistance of Sweet Potato to Fusarium oxysporum

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.00197

DOI=10.3389/fpls.2017.00197

ISSN=1664-462X

ABSTRACT=<p>SWEET (Sugars Will Eventually be Exported Transporter) proteins, a novel family of sugar transporters, mediate the diffusion of sugars across cell membranes and acts as key players in sucrose phloem loading. Manipulation of SWEET genes in plants leads to various effects on resistance to biotic and abiotic stresses due to disruption of sugar efflux and changes in sugar distribution. In this study, a member of the SWEET gene family, <italic>IbSWEET10</italic>, was cloned from the sweet potato line ND98. mRNA expression analysis in sweet potato and promoter β-Glucuronidase analysis in <italic>Arabidopsis</italic> showed that <italic>IbSWEET10</italic> is highly expressed in leaves, especially in vascular tissue. Transient expression in tobacco epidermal cells revealed plasma membrane localization of IbSWEET10, and heterologous expression assays in yeast indicated that <italic>IbSWEET10</italic> encodes a sucrose transporter. The expression level of <italic>IbSWEET10</italic> was significantly up-regulated in sweet potato infected with <italic>Fusarium oxysporum</italic> Schlecht. f. sp. <italic>batatas.</italic> Further characterization revealed <italic>IbSWEET10</italic>-overexpressing sweet potato lines to be more resistant to <italic>F. oxysporum</italic>, exhibiting better growth after infection compared with the control; conversely, RNA interference (RNAi) lines showed the opposite results. Additionally, the sugar content of <italic>IbSWEET10</italic>-overexpression sweet potato was significantly reduced, whereas that in RNAi plants was significantly increased compared with the control. Therefore, we suggest that the reduction in sugar content caused by <italic>IbSWEET10</italic> overexpression is the major reason for the enhanced <italic>F. oxysporum</italic> resistance of the transgenic plants. This is the first report that the IbSWEET10 transporter contributes to the resistance of sweet potato to <italic>F. oxysporum</italic>. The <italic>IbSWEET10</italic> gene has the great potential to be used for improving the resistance to <italic>F. oxysporum</italic> in sweet potato and other plants.</p>