小麦锈菌夏孢子经盐酸处理后的形态观察

Morphological observation of wheat rust urediniospores with hydrochloric acid solutions

为了快速区分小麦条锈菌、叶锈菌和秆锈菌,用不同浓度的盐酸处理3种小麦锈菌的新鲜夏孢子和在4℃冰箱内保存4个月以上的锈菌夏孢子,在显微镜下观察夏孢子形态以及原生质体变化。结果表明,24.5%、28.5%、32.5%、36.5%4种浓度的盐酸处理条锈菌夏孢子后其原生质体均浓缩成多个分散的小团。而同样方法处理叶锈菌和秆锈菌新鲜菌种时其原生质体浓缩成一个大团或多个小团,浓缩成一个大团的比例随盐酸浓度的增大而提高;用不同浓度盐酸处理保存4个月以上的2种小麦锈菌时,95%以上的夏孢子原生质体浓缩成多个分散的小团,少数(不超过5%)的夏孢子原生质体浓缩成一个大团。研究还发现叶锈菌和秆锈菌夏孢子活力、盐酸浓度等对夏孢子原生质体浓缩状况有很大影响,且与病菌生理小种有一定的关系。因此,锈菌夏孢子经36.5%浓盐酸处理后的原生质体浓缩状况只能作为小麦锈病田间快速诊断检测的辅助手段,不能作为锈病种类鉴别的唯一标准,必须结合病害症状特征、孢子形态以及分子生物学方法等进行综合判别。

Morphological characters and protoplast change of the urediniospores of Puccinia striiformis f. sp. tritici （Pst）, P. triticina （Pt） and P. graminis f. sp. tritici （Pgt） were observed under the microscope with different solutions of hydrochloric acid, so as to differentiate the species of wheat rusts. The results indicated that the protoplasts of the fresh Pst urediniospores just collected from wheat leaves shrank into many small dollops under the hydrochloric acid of 24.5 % to 36.50%. Conversely, the protoplasts of fresh Pt and Pgt urediniospores concentrated on one dollop in the middle of the spores or many small dollops under the same conditions, and the percentage of urediniospores shrinking into one dollop increased with the concentration of hydrochloric acid. The protoplasts of more than 95 % urediniospores stored in a refrigerator of 4 ℃ for above 4 months shrank into many small dollops, but only less than 5 % shrank into one dollop. The impacts of urediniospore activity, concentration of hydrochloric acid and physiological races of rust fungi on protoplast shrinking were also studied. It suggested that protoplast shrinking of uredi- niospores at higher concentration of hydrochloric acid （36.5%） could be used to differentiate stripe rust, leaf rust and stem rust, but it was not the exclusive approach. Disease diagnoses in the field should he conducted by combining it with symptoms, morphological characters of the pathogens and even molecular approaches.