STAUROSPORINE AND TEMPERATURE SENSITIVE3 (STT3) is a catalytic subunit of oligosaccharyltransferase, which is important for asparagine-linked glycosylation. Sharp eyespot, caused by the necrotrophic fungal pathogen Rhizoctonia cerealis, is a devastating disease of bread wheat. However, the molecular mechanisms underlying wheat defense against R. cerealis are still largely unclear. In this study, we identified TaSTT3a and TaSTT3b, two STT3 subunit genes from wheat and reported their functional roles in wheat defense against R. cerealis and increasing grain weight. The transcript abundance of TaSTT3b-2B was associated with the degree of wheat resistance to R. cerealis and induced by both R. cerealis and exogenous jasmonic acid (JA). Overexpression of TaSTT3b-2B significantly enhanced resistance to R. cerealis, grain weight, and JA content in transgenic wheat subjected to R. cerealis stress, while silencing of TaSTT3b-2B compromised resistance of wheat to R. cerealis. Transcriptomic analysis showed that TaSTT3b-2B affected the expression of a series of defense-related genes and JA biosynthesis–related genes, as well as genes coding starch synthase and sucrose synthase. Application of exogenous JA elevated expression levels of the abovementioned defense- and grain weight–related genes, and rescuing the resistance of TaSTT3b-2B–silenced wheat to R. cerealis, while pretreatment with sodium diethyldithiocarbamate, an inhibitor of JA synthesis, attenuated the TaSTT3b-2B–mediated resistance to R. cerealis, suggesting that TaSTT3b-2B played critical roles in regulating R. cerealis resistance and grain weight via JA biosynthesis. Altogether, this study reveals new functional roles of TaSTT3b-2B in regulating plant innate immunity and grain weight, and illustrates its potential application value for wheat molecular breeding.

中文翻译：

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TaSTT3b-2B 的过表达提高了小麦对尖锐眼斑的抗性并增加了粒重

星形孢菌素和温度敏感 3 (STT3) 是寡糖基转移酶的催化亚基，对天冬酰胺连接的糖基化很重要。由坏死性真菌病原体谷物丝核菌引起的尖锐眼斑是面包小麦的一种破坏性病害。然而，小麦对谷类稻瘟病菌的防御分子机制仍不清楚。在这项研究中，我们鉴定了来自小麦的两个 STT3 亚基基因TaSTT3a和TaSTT3b，并报告了它们在小麦防御R. grainis和增加粒重中的功能作用。TaSTT3b-2B的转录本丰度与小麦对R. grainis 的抗性程度相关并由R. grainis和外源茉莉酸 (JA) 诱导。TaSTT3b-2B的过表达显着增强了转基因小麦对稻谷稻瘟病胁迫的抗性、粒重和 JA 含量，而沉默TaSTT3b -2B则损害了小麦对稻瘟病的抗性。 麦片_ 转录组学分析表明TaSTT3b-2B影响了一系列防御相关基因和JA生物合成相关基因的表达，以及编码淀粉合酶和蔗糖合酶的基因的表达。外源 JA 的应用提高了上述防御和粒重相关基因的表达水平，并挽救了TaSTT3b-2B沉默的小麦对R. grainis 的抗性，而用 JA 合成抑制剂二乙基二硫代氨基甲酸钠预处理，减弱了TaSTT3b -2B介导的谷类抗性，表明TaSTT3b -2B在调控谷类抗性和粒重中起关键作用JA生物合成。总之，本研究揭示了TaSTT3b-2B在调节植物先天免疫和粒重中的新功能作用，并说明了其在小麦分子育种中的潜在应用价值。