Assessment of deoxynivalenol and deoxynivalenol derivatives in <i>Fusarium graminearum</i>-inoculated Canadian maize inbreds

The prevalence of maize, wheat and other cereal crops in Ontario, Canada, has led to frequent epidemics of ear rot and head blight disease caused by the broad host pathogen <i>Fusarium graminearum</i>. This fungus produces the trichothecene deoxynivalenol (DON) which is one of the most common mycotoxins contaminating food and feed globally and poses a risk to human and animal health. DON is commonly glycosylated by plant hosts into deoxynivalenol-3-glucoside (DON-3G) as part of a defence mechanism to detoxify and sequester mycotoxins. However, it has been documented that DON-3G can be hydrolyzed in the digestive system of animals, increasing the bioavailability of DON. There is a need for additional documentation of the incidence and ratio of DON-3G to DON in Canadian cereal crops. We investigated the occurrence and relative proportion of DON and modified DON compounds in Canadian-adapted maize germplasm with a wide range of ear rot tolerance. Forty-nine maize inbreds were manually challenged (kernel inoculation) with <i>F. graminearum</i> (15-ADON chemotype) as well as phenotyped for tolerance to Gibberella ear rot (GER) under field conditions. LC/MS was used to analyse 581 maize samples for DON, DON-3G, 15-ADON, and 15-ADON-3G. The DON-3G to DON mean molar ratio ranged from 3.1 to 19.7%. DON content was positively correlated with GER disease severity (r = 0.66, <i>p</i> &lt; 0.01), while the DON-3G:DON molar ratio and disease severity were negatively correlated (r = −0.64, <i>p</i> &lt; 0.001). Thus, GER-tolerant maize genotypes had relatively lower total DON content and higher DON-3G:DON ratios.

加拿大安大略省玉米、小麦及其他谷类作物种植广泛，由此导致由广谱寄主病原菌禾谷镰孢（*Fusarium graminearum*）引发的穗腐病与赤霉病频繁暴发。该真菌可产生单端孢霉烯族毒素脱氧雪腐镰刀菌烯醇（deoxynivalenol, DON）——这是全球范围内污染食品与饲料最常见的真菌毒素之一，对人类与动物健康均存在健康风险。作为解毒并螯合真菌毒素的防御机制之一，植物宿主通常会将DON糖基化为脱氧雪腐镰刀菌烯醇-3-葡萄糖苷（deoxynivalenol-3-glucoside, DON-3G）。但已有研究证实，DON-3G可在动物消化系统中被水解，进而提升DON的生物利用度。目前仍需补充加拿大谷类作物中DON-3G与DON的检出率及二者比例的相关数据。

本研究针对一系列具有不同赤霉穗腐病（Gibberella ear rot, GER）抗性的加拿大适应性玉米种质，探究了DON及其修饰型毒素的存在情况与相对占比。研究人员对49份玉米自交系进行人工籽粒接种15-ADON化学型的禾谷镰孢，并在田间条件下对其抗赤霉穗腐病性状开展表型鉴定。采用液相色谱-质谱联用技术（LC/MS）对581份玉米样本中的DON、DON-3G、15-ADON及15-ADON-3G进行检测分析。

结果显示，DON-3G与DON的平均摩尔比值介于3.1%至19.7%之间。DON含量与赤霉穗腐病病情严重程度呈显著正相关（r=0.66, *p*<0.01），而DON-3G:DON摩尔比值与病情严重程度呈显著负相关（r=-0.64, *p*<0.001）。由此可见，抗赤霉穗腐病的玉米基因型通常具有相对更低的总DON含量与更高的DON-3G:DON摩尔比值。