Triazole fungicides have been used for seed treatment to control soilborne diseases of maize, but seedlings coming from triazole-coated seed show serious phytotoxicity under chilling stress. To understand this phytotoxic impact, maize seed was treated with four triazoles fungicides and the corresponding seedlings were analysed on growth and gene expression. We found that maize seed coated with difenoconazole and tebuconazole exhibited either no or increased effects on germination and growth of maize at 25 °C, regardless of chemical concentrations. When maize seedlings were subjected to chilling treatment, however, their growth was significantly inhibited, and the inhibition was positively correlated with the rate of triazole application. Mesocotyl length decreased by 32.19-44.73% by difenoconazole, and 23.53-32.08% by tebuconazolet at rates of 1:50 and 1:25, respectively. However, myclobutanil did not have any effects at any temperatures. The contents of the gibberellin GA12 and abscisic acid in maize seedlings developed from difenoconazole- or tebuconazole-coated seed were significantly increased under chilling stress. The expression of two key catabolic enzyme genes, GA2ox3 and GA2ox4, was significantly up-regulated immediately following chilling stress and 2 days after recovery at 25 °C in the seedlings treated with difenoconazole or tebuconazole. This imbalance in phytohormones may explain why difenoconazole- or tebuconazole-coated seed more likely results in the phytotoxicity of maize seedlings under a low temperature condition during seed emergence and seedling growth. Since myclobutanil did not have this negative effect, it can be applied for seed coating in areas where temperatures are low during early seedling growth.

中文翻译：

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受三唑类种子处理的影响，玉米幼苗对冷胁迫的激素和酶促反应。

三唑杀真菌剂已用于种子处理，以控制玉米的土壤传播疾病，但是来自三唑涂层种子的幼苗在寒冷胁迫下表现出严重的植物毒性。为了了解这种植物毒性作用，用四种三唑类杀菌剂处理了玉米种子，并分析了相应幼苗的生长和基因表达。我们发现，在25°C下，无论化学浓度如何，用二苯并噻唑和戊唑醇包被的玉米种​​子对玉米的萌发和生长均没有表现出作用，也没有表现出增加的作用。但是，当对玉米幼苗进行冷冻处理时，它们的生长被显着抑制，并且该抑制与三唑的施用率正相关。苯甲康唑的中胚轴长度减少了32.19-44.73％，戊丁康唑的中胚轴长度减少了23.53-32.08％：50和1:25。但是，myclobutanil在任何温度下都没有任何作用。在低温胁迫下，由二苯并噻唑或戊唑醇包衣的种子培育的玉米幼苗中赤霉素GA12和脱落酸的含量显着增加。低温胁迫后和在25°C恢复2天后，用苯芬康唑或戊唑醇处理的幼苗中两个关键的分解代谢酶基因GA2ox3和GA2ox4的表达显着上调。植物激素的这种不平衡可能解释了为什么在种子出苗和幼苗生长过程中的低温条件下，用二苯并康唑或戊唑醇包衣的种子更有可能导致玉米幼苗的植物毒性。由于myclobutanil没有负面影响，