Hexaploid spring wheat (Triticum aestivum) may exhibit significant crown rot disease responses to infection by Fusarium pseudograminearum, with a range of susceptibility levels available in commercial cultivars. Dry conditions during grain-fill may lead to the expression of prematurely senescing culms, which typically fail to set grain. Assessment of hexaploid spring wheat plants exhibiting both non-senescent and prematurely senescent culms was performed using visual discolouration, Fusarium pseudograminearum biomass, vascular colonisation and quantification of wheat DNA in culm sections sampled at three different heights above the crown and at the peduncle. A comparison of these parameters at four time points from milk development, when senescent culms are first observed, to maturity was conducted. Samples from six commercial cultivars were collected in 2014 from Narrabri and Tamworth, New South Wales and Wellcamp, Queensland. Prematurely senescent culms exhibited greater visual discolouration, Fusarium pseudograminearum biomass and vascular colonisation than non-senescent culms in each cultivar. Colonisation of xylem and phloem tissue was extensive in the basal portions of prematurely senescent culms (36 to 99%), and suggests significant impacts on water and nutrient movement during crown rot disease. Maturation coincided with significant changes in Fusarium pseudograminearum biomass and vascular colonisation. Wheat DNA content varied among cultivars, culm conditions, culm sections and sampling times. The variation in the severity of disease states between culms of the same plant suggests that the timing of initiation of infection in individual culms may vary.

中文翻译：

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六倍体春小麦茎秆表现出与镰孢镰刀菌冠腐病相关的过早衰老（死头）的病害响应。

六倍体春小麦（Triticum aestivum）对伪镰刀菌（Fusarium pseudograminearum）的感染可能表现出明显的冠腐病反应，在商业品种中可获得一定的敏感性水平。谷物灌装过程中的干燥条件可能导致过早的茎秆表达，通常无法凝固谷物。使用视觉变色镰刀菌（Fusarium pseudograminearum）对显示非衰老和早衰茎的六倍体春小麦植物进行评估在茎冠上方和花梗的三个不同高度处取样的茎秆切片中的小麦生物量，血管定植和小麦DNA定量。从最初观察到衰老的牛奶发育到成熟的四个时间点对这些参数进行了比较。2014年，从六个新品种的样品中采集了新南威尔士州的纳拉布里和塔姆沃思以及昆士兰州的韦尔坎普。过早衰老的茎杆表现出更大的视觉变色，假镰刀镰刀菌每个品种的生物量和血管定植率均高于非衰老茎。木质部和韧皮部组织的定植在过早衰老的茎的基部广泛（36％至99％），并表明在冠腐病期间对水分和养分运动有显着影响。成熟与假镰刀菌生物量和血管定植的显着变化相吻合。小麦DNA含量因品种，茎秆条件，茎秆切片和采样时间而异。同一植物茎间病态严重程度的变化表明，单个茎间感染开始的时间可能会有所不同。