ABSTRACT

Sugars Will Eventually be Exported Transporter (SWEET) is a newly characterized family of sugar transporters, which plays critical roles in plant–pathogen interactions. However, the function of SWEET in tobacco and its interaction with Fusarium oxysporum, a causal agent of root rot, remain unclear. This study aimed to dissect the function of NtSWEETs in tobacco root rot using stem bases from tobacco plants inoculated with F. oxysporum. RNA-sequencing (RNA-Seq) analysis was performed, and the results indicated that Sucrose Transporter 4 (NtSUC4), Sugar Transporter 12 (NtSTP12), Hexose Transporter 6 (NtHEX6), NtSWEET1, NtSWEET3b, and NtSWEET12 were downregulated by infection with F. oxysporum. The expression of NtSWEET1, but not of NtSUC4, NtSTP12, NtHEX6, NtSWEET3b, or NtSWEET12, was suppressed at all the time points tested after inoculation with F. oxysporum. The NtSWEET1-green fluorescent protein was localized on the plasma membrane and possessed the ability to transport glucose, fructose and galactose. Compared with the wild-type plants, NtSWEET1 RNAi plants were more susceptible to root rot, indicating that NtSWEET1 positively regulated the defense of tobacco against root rot. This study identified the role of SWEETs in tobacco and their interaction with F. oxysporum. The results might be useful in protecting tobacco plants from root rot.

摘要

糖最终将被输出转运蛋白 (SWEET) 是一个新发现的糖转运蛋白家族，它在植物-病原体相互作用中发挥着关键作用。然而，SWEET 在烟草中的作用及其与根腐病病原体尖孢镰刀菌的相互作用仍不清楚。本研究旨在利用接种尖孢镰刀菌的烟草植物茎基来剖析NtSWEETs在烟草根腐病中的作用。进行了 RNA 测序 (RNA-Seq) 分析，结果表明蔗糖转运蛋白 4 ( NtSUC4)、糖转运蛋白 12 ( NtSTP12)、己糖转运蛋白 6 ( NtHEX6)、NtSWEET1、NtSWEET3b和NtSWEET12被尖孢镰刀菌感染下调。NtSWEET1的表达，但不是NtSUC4、NtSTP12、NtHEX6、NtSWEET3b或NtSWEET12的表达，在接种尖孢镰刀菌后测试的所有时间点均受到抑制。NtSWEET1-绿色荧光蛋白位于质膜上，具有运输葡萄糖、果糖和半乳糖的能力。与野生型植物相比，NtSWEET1 RNAi植物对根腐病的敏感性更高，表明NtSWEET1正向调节烟草对根腐病的防御。本研究确定了 SWEET 在烟草中的作用及其与尖孢镰刀菌的相互作用. 该结果可能有助于保护烟草植物免于根腐病。