Department of Plant Pathology, North Carolina State University, Raleigh, NC, USA.
Phytopathology. 2013 May;103(5):460-71. doi: 10.1094/PHYTO-03-12-0054-R.
Fusarium head blight (FHB) affects whole spikes of small grain plants, yet little is known about how FHB develops following infection, or about the concentration or progression of the mycotoxin deoxynivalenol (DON) in non-grain spike tissues. Fusarium mycotoxin levels in whole small-grain spikes are of concern to producers of whole-crop silage, as well as users of straw containing chaff for animal bedding or winter livestock rations. A 2-year field experiment was performed in Kinston, NC to reveal the time course of FHB development. Eight winter wheat cultivars with varying levels of FHB resistance were used in the 2006 experiment, and four of them were used in 2007. Plots were spray-inoculated with Fusarium graminearum macroconidia at mid-anthesis. Four durations of post-anthesis mist were applied: 0, 10, 20, or 30 days. Spike samples were collected and bulked by plot at 15, 25, 35, 45, 55, and 65 days after anthesis (daa); samples were separated into grain, glume, and rachis fractions. Increasing durations of post-anthesis moisture elevated grain DON and reduced the effect of cultivar on DON, presumably by affecting the expression of resistance, in all spike tissues. Fusarium-damaged kernels increased from early kernel-hard to harvest-ripe in both years. Percent infected kernels increased from medium-milk to harvest-ripe. During grainfill, DON concentrations declined in grain but increased in rachises and glumes, peaking at early kernel-hard, before declining. Higher mean and maximum DON levels were observed in rachises and glumes than in grain. Estimated whole-spike DON peaked at early kernel-hard. In a high-FHB year, whole-plant harvest for forage should be conducted as early as possible. Straw that may be consumed by livestock could contain significant amounts of DON in chaff, and DON can be minimized if straw is sourced from low-symptom crops. Cultivar FHB resistance ratings and disease data should be useful in predicting whole-spike DON levels. Overall, associations between grain DON levels in harvest-ripe and prior samples were stronger the later the prior samples were collected, suggesting limits to the possibility of predicting harvest-ripe grain DON from earlier levels.
镰刀菌穗腐病（FHB）会影响小粒谷物的整个穗部，但对于感染后 FHB 的发展情况，以及非谷物穗部组织中真菌毒素脱氧雪腐镰刀菌烯醇（DON）的浓度或进展情况，我们知之甚少。对于整株青贮作物的生产者以及使用含有糠秕的秸秆作为动物垫料或冬季牲畜饲料的用户来说，整株小粒谷物穗部中的镰刀菌真菌毒素含量令人担忧。在北卡罗来纳州金斯顿进行了一项为期两年的田间试验，以揭示 FHB 发展的时间进程。2006 年试验中使用了 8 个抗 FHB 能力不同的冬小麦品种，其中 4 个品种在 2007 年使用。在花期中，用镰刀菌的大分生孢子喷雾接种。在花后，共应用了 4 个不同持续时间的雾期：0、10、20 或 30 天。在授粉后 15、25、35、45、55 和 65 天（授粉后天，daa），按小区采集并混合穗部样本；样本分为籽粒、颖片和穗轴部分。在所有穗部组织中，随着花后水分持续时间的增加，籽粒 DON 增加，而品种对 DON 的影响降低，这可能是通过影响抗性的表达。在这两年中，从早期籽粒坚硬到收获成熟，受镰刀菌损伤的籽粒都在增加。受感染的籽粒百分比从中乳期增加到收获成熟。在灌浆期间，DON 浓度在籽粒中下降，但在穗轴和颖片中增加，在早期籽粒坚硬时达到峰值，然后下降。在穗轴和颖片中观察到的平均和最大 DON 水平高于籽粒。整个穗部 DON 的估计峰值出现在早期籽粒坚硬时。在 FHB 高发年份，应尽早进行全株收获以作青贮。可能被牲畜消耗的秸秆，如果来自症状较轻的作物，可能在糠秕中含有大量的 DON，从而可以将 DON 降到最低。品种的 FHB 抗性等级和疾病数据将有助于预测整个穗部 DON 水平。总体而言，收获成熟和前期样本中籽粒 DON 水平之间的相关性越强，前期样本的采集时间越晚，这表明从早期水平预测收获成熟时的籽粒 DON 存在一定的局限性。
