Barley, host to the wheat and rye attacking forms of the stem rust pathogen, Puccinia graminis (Pg), is considered inherently more resistant to Pg than wheat. To investigate whether this enhanced basal defence is associated with early infection or colonisation processes, adult plants of selected barley and wheat entries were inoculated with Pg f. sp. tritici (Pgt) races BNGSC and PTKST, and Pg f. sp. secalis (Pgs) isolate UVPgs1. Flag leaf sheaths on the last stem internode were sampled for analysis. Using scanning electron microscopy and epidermal stripping, early Pg infection structure development was compared between barley and wheat. Sub-stomatal vesicle appearance and production of haustorial mother cells were similar at 24 and 48 h post inoculation (hpi), respectively. Significant variation occurred among host entries (P ≤ 0.01) for colony size and fungal biomass at 120 hpi. Differences between the Pgt races and the Pgs isolate as well as the host entry-Pg isolate interaction proved insignificant (P ≥ 0.05). The period between 120 and 240 hpi may hold some explanation for the perceived lower stem rust receptivity in barley, since a steep increase in accumulated fungal biomass observed in the susceptible wheat Line 37 − 07 was not seen in the susceptible barley entries at the same time interval.

中文翻译：

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比较大麦和小麦中禾本科锈菌的感染和定植

大麦是小麦和黑麦茎锈病病原体 Puccinia graminis (Pg) 的宿主，被认为天生比小麦对 Pg 更具抗性。为了研究这种增强的基础防御是否与早期感染或定植过程有关，用 Pg f 接种选定大麦和小麦的成年植株。sp. 小麦 (Pgt) 种族 BNGSC 和 PTKST，以及 Pg f。sp. secalis (Pgs) 隔离 UVPgs1。对最后一个茎节间的旗叶鞘取样进行分析。使用扫描电子显微镜和表皮剥离，比较了大麦和小麦之间早期 Pg 感染结构的发展。在接种后 24 小时和 48 小时 (hpi)，气孔下囊泡外观和吸器母细胞的产生相似。主机条目之间存在显着差异（P ≤ 0。01) 在 120 hpi 时的菌落大小和真菌生物量。Pgt 种族和 Pgs 分离株之间的差异以及宿主入口-Pg 分离株相互作用证明不显着（P ≥ 0.05）。120 到 240 hpi 之间的时期可能对大麦中感知到的茎锈病易感性较低提供一些解释，因为在易感小麦品系 37 - 07 中观察到的累积真菌生物量急剧增加并未同时在易感大麦条目中观察到间隔。