The Key Lab of Plant Pathology of Hubei Province, Huazhong Agricultural University, Wuhan, Hubei, 430070, People's Republic of China.
College of Plant Protection, China Agricultural University, Beijing, 100193, People's Republic of China.
Curr Microbiol. 2020 Oct;77(10):2766-2774. doi: 10.1007/s00284-020-02072-6. Epub 2020 Jun 11.
Ustiloxin is a kind of 13-membered cyclic peptides found in mature rice false smut generated by Ustilaginoidea virens infecting rice spikelet. So far, six kinds of ustiloxins have been identified from false smut balls (FSBs) in which ustiloxin A is the main component. The toxins can not only inhibit the growth of rice, wheat, and corn, but also poison people and animals. However, so far, there have been few studies of the content of ustiloxin except that in mature FSB. The effect of ustiloxins on the process of infection has not been clarified. In this study, the technique of artificial inoculation coupled with UPLC-ESI-MS was introduced to investigate the content of ustiloxins in the course of infection. The initial formation time of ustiloxin A, B, C, D, F, and G was no later than 5, 5, 9, 7, 7, and 9 days post inoculation (dpi) prior to FSB's formation, respectively. The content of ustiloxin A per spikelet was increased rapidly from 6.0 ng at 5 dpi to 14,157.1 ng at 25 dpi. Meanwhile, the content of ustiloxin A per dry weight (DW) of the FSBs also peaked at 1321.2 μg/g at 25 dpi. Interestingly, both the contents of ustiloxin A per dry weight and per spikelet were significantly reduced from 25 to 30 dpi. Transcriptome sequencing revealed that a total of 146 transcripts (103 upregulated and 43 downregulated) were significantly changed in rice spikelets after 3-h acute exposure to 100 ng ustiloxin A. In addition, several of the significantly altered genes were validated by RT-qPCR.
毒麦宁是一种由禾谷镰刀菌（Ustilaginoidea virens）感染水稻小穗产生的成熟稻曲病菌中的 13 元环肽。迄今为止，已从稻曲病菌球（FSB）中鉴定出六种毒麦宁（ustiloxin），其中毒麦宁 A 是主要成分。这些毒素不仅能抑制水稻、小麦和玉米的生长，还能毒害人和动物。然而，到目前为止，除了成熟的 FSB 之外，对毒麦宁的含量研究很少。毒麦宁对感染过程的影响也不清楚。在本研究中，采用人工接种结合 UPLC-ESI-MS 技术，研究了感染过程中毒麦宁的含量。毒麦宁 A、B、C、D、F 和 G 的形成时间分别不晚于接种后 5、5、9、7、7 和 9 天，早于 FSB 的形成。每个小穗中毒麦宁 A 的含量从 5dpi 的 6.0ng 迅速增加到 25dpi 的 14157.1ng。同时，FSB 中每克干重（DW）的毒麦宁 A 含量也在 25dpi 时达到 1321.2μg/g 的峰值。有趣的是，从 25 到 30dpi，毒麦宁 A 的每克干重和每小穗含量均显著降低。转录组测序显示，水稻小穗在急性暴露于 100ng 毒麦宁 A 3 小时后，共 146 个转录本（103 个上调，43 个下调）发生明显变化。此外，通过 RT-qPCR 验证了几个明显改变的基因。
