Key message

Resistance conferred by the Cre8 locus of wheat prevents cereal cyst nematode feeding sites from reaching and invading root metaxylem vessels.

Abstract

Cyst nematodes develop syncytial feeding sites within plant roots. The success of these sites is affected by host plant resistance. In wheat (Triticum aestivum L.), ‘Cre’ loci affect resistance against the cereal cyst nematode (CCN) Heterodera avenae. To investigate how one of these loci (Cre8, on chromosome 6B) confers resistance, CCN-infected root tissue from susceptible (−Cre8) and resistant (+Cre8) wheat plants was examined using confocal microscopy and laser ablation tomography. Confocal analysis of transverse sections showed that feeding sites in the roots of −Cre8 plants were always adjacent to metaxylem vessels, contained many intricate ‘web-like’ cell walls, and sometimes ‘invaded’ metaxylem vessels. In contrast, feeding sites in the roots of +Cre8 plants were usually not directly adjacent to metaxylem vessels, had few inner cell walls and did not ‘invade’ metaxylem vessels. Models based on data from laser ablation tomography confirmed these observations. Confocal analysis of longitudinal sections revealed that CCN-induced xylem modification that had previously been reported for susceptible (−Cre8) wheat plants is less extreme in resistant (+Cre8) plants. Application of a lignin-specific stain revealed that secondary thickening around xylem vessels in CCN-infected roots was greater in +Cre8 plants than in −Cre8 plants. Collectively, these results indicate that Cre8 resistance in wheat acts by preventing cyst nematode feeding sites from reaching and invading root metaxylem vessels.

中文翻译：

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三维成像显示，胞囊线虫摄食位点相对于木质部血管的位置在易感和抗性小麦之间存在差异

关键信息

小麦的Cre8基因座赋予的抗性可防止谷物包囊线虫取食部位到达和侵入根间木质部血管。

抽象的

包囊线虫在植物根部内发育合胞体取食位点。这些站点的成功受寄主植物抗性的影响。在小麦 ( Triticum aestivum  L.) 中，' Cre ' 位点影响对谷物胞囊线虫 (CCN)  Heterodera avenae的抗性。为了研究这些基因座之一（Cre8 ，在染色体 6B 上）如何赋予抗性，使用共聚焦显微镜和激光烧蚀断层扫描检查了来自易感 (− Cre8 ) 和抗性 (+ Cre8 ) 小麦植物的 CCN 感染的根组织。横切面的共聚焦分析表明 - Cre8根部的摄食位点植物总是与后木质部血管相邻，含有许多错综复杂的“网状”细胞壁，有时还会“侵入”后木质部血管。相比之下，+ Cre8 植物根部的摄食位点通常不直接与间木质部血管相邻，内细胞壁很少，并且没有“侵入”间木质部血管。基于激光烧蚀断层扫描数据的模型证实了这些观察结果。纵向切片的共聚焦分析表明，CCN 诱导的木质部修饰先前已报道用于易感 (− Cre8 ) 小麦植物，但在抗性 (+ Cre8 ) 植物中不太极端。木质素特异性染色的应用表明，在 CCN 感染的根中，木质部血管周围的二次增厚在 + Cre8中更大 植物比 - Cre8 植物。总的来说，这些结果表明 小麦中的Cre8 抗性通过阻止胞囊线虫摄食位点到达和侵入根间木质部血管而起作用。